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1. Ultra-High-Energy Gamma-Ray Bubble around Microquasar V4641 Sgr

Author: Alfaro, R., Alvarez, C., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Babu, R., Belmont-Moreno, E., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Cotti, U., Cotzomi, J., de León, S. Coutiño, De la Fuente, E., Depaoli, D., Di Lalla, N., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Durocher, M., Díaz-Vélez, J. C., Engel, K., Espinoza, C., Fan, K. L., Fang, K., Fraija, N., Fraija, S., García-González, J. A., Garfias, F., Muñoz, A. Gonzalez, González, M. M., Goodman, J. A., Groetsch, S., Harding, J. P., Herzog, I., Hinton, J., Huang, D., Hueyotl-Zahuantitla, F., Hüntemeyer, P., Iriarte, A., Joshi, V., Kaufmann, S., Kieda, D., de León, C., Lee, J., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Malone, K., Martinez, O., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Olivera-Nieto, L., Omodei, N., Osorio, M., Araujo, Y. Pérez, Pérez-Pérez, E. G., Rho, C. D., Rosa-González, D., Ruiz-Velasco, E., Salazar, H., Salazar-Gallegos, D., Sandoval, A., Schneider, M., Serna-Franco, J., Smith, A. J., Son, Y., Springer, R. W., Tibolla, O., Tollefson, K., Torres, I., Torres-Escobedo, R., Turner, R., Ureña-Mena, F., Varela, E., Villaseñor, L., Wang, X., Watson, I. J., Willox, E., Yun-Cárcamo, S., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Microquasars are laboratories for the study of jets of relativistic particles produced by accretion onto a spinning black hole. Microquasars are near enough to allow detailed imaging of spatial features across the multiwavelength spectrum. The recent extension of the spatial morphology of a microquasar, SS 433, to TeV gamma rays \cite{abeysekara2018very} localizes the acceleration of electrons at shocks in the jet far from the black hole \cite{hess2024ss433}. Here we report TeV gamma-ray emission from another microquasar, V4641~Sgr, which reveals particle acceleration at similar distances from the black hole as SS~433. Additionally, the gamma-ray spectrum of V4641 is among the hardest TeV spectra observed from any known gamma-ray source and is detected up to 200 TeV. Gamma rays are produced by particles, either electrons or hadrons, of higher energies. Because electrons lose energy more quickly the higher their energy, such a spectrum either very strongly constrains the electron production mechanism or points to the acceleration of high-energy hadrons. This observation suggests that large-scale jets from microquasars could be more common than previously expected and that microquasars could be a significant source of Galactic cosmic rays. high energy gamma-rays also provide unique constraints on the acceleration mechanisms of extra-Galactic cosmic rays postulated to be produced by the supermassive black holes and relativistic jets of quasars. The distance to quasars limits imaging studies due to insufficient angular resolution of gamma-rays and due to attenuation of the highest energy gamma-rays by the extragalactic background light.
Published: 2024
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2. Very-high-energy $\gamma$-ray emission from young massive star clusters in the Large Magellanic Cloud

Author: Aharonian, F., Benkhali, F. Ait, Aschersleben, J., Ashkar, H., Backes, M., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernlöhr, K., Böttcher, M., Bolmont, J., de Lavergne, M. de Bony, Borowska, J., Brose, R., Brown, A., Brun, F., Bruno, B., Burger-Scheidlin, C., Casanova, S., Celic, J., Cerruti, M., Chand, T., Chandra, S., Chen, A., Chibueze, J., Chibueze, O., Cotter, G., Cristofari, P., Devin, J., Djannati-Ataï, A., Djuvsland, J., Dmytriiev, A., Egberts, K., Einecke, S., Feijen, K., Filipovic, M., Fontaine, G., Funk, S., Gabici, S., Gallant, Y. A., Glicenstein, J. F., Glombitza, J., Grolleron, G., Haerer, L., Heß, B., Hinton, J. A., Hofmann, W., Holch, T. L., Horns, D., Huang, Zhiqiu, Jamrozy, M., Jankowsky, F., Jung-Richardt, I., Kasai, E., Katarzyński, K., Khatoon, R., Khélifi, B., Kluźniak, W., Komin, Nu., Kosack, K., Kostunin, D., Kundu, A., Lang, R. G., Stum, S. Le, Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Mackey, J., Marandon, V., Martí-Devesa, G., Marx, R., Mehta, A., Mitchell, A., Moderski, R., Moghadam, M. O., Mohrmann, L., Montanari, A., Moulin, E., de Naurois, M., Niemiec, J., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Pensec, U., Peron, G., Pühlhofer, G., Quirrenbach, A., Ravikularaman, S., Regeard, M., Reimer, A., Reimer, O., Ren, H., Renaud, M., Reville, B., Rieger, F., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sabri, K., Sahakian, V., Salzmann, H., Santangelo, A., Sasaki, M., Schäfer, J., Schüssler, F., Schutte, H. M., Sol, H., Spencer, S., Stawarz, Ł., Steinmassl, S., Steppa, C., Streil, K., Sushch, I., Taylor, A. M., Terrier, R., Tsirou, M., Tsuji, N., van Eldik, C., Vecchi, M., Venter, C., Vink, J., Wagner, S. J., White, R., Wierzcholska, A., Zacharias, M., Zdziarski, A. A., Zech, A., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The Tarantula Nebula in the Large Magellanic Cloud is known for its high star formation activity. At its center lies the young massive star cluster R136, providing a significant amount of the energy that makes the nebula shine so brightly at many wavelengths. Recently, young massive star clusters have been suggested to also efficiently produce high-energy cosmic rays, potentially beyond PeV energies. Here, we report the detection of very-high-energy $\gamma$-ray emission from the direction of R136 with the High Energy Stereoscopic System, achieved through a multicomponent, likelihood-based modeling of the data. This supports the hypothesis that R136 is indeed a very powerful cosmic-ray accelerator. Moreover, from the same analysis, we provide an updated measurement of the $\gamma$-ray emission from 30 Dor C, the only superbubble detected at TeV energies presently. The $\gamma$-ray luminosity above $0.5\,\mathrm{TeV}$ of both sources is $(2-3)\times 10^{35}\,\mathrm{erg}\,\mathrm{s}^{-1}$. This exceeds by more than a factor of 2 the luminosity of HESS J1646$-$458, which is associated with the most massive young star cluster in the Milky Way, Westerlund 1. Furthermore, the $\gamma$-ray emission from each source is extended with a significance of $>3\sigma$ and a Gaussian width of about $30\,\mathrm{pc}$. For 30 Dor C, a connection between the $\gamma$-ray emission and the nonthermal X-ray emission appears likely. Different interpretations of the $\gamma$-ray signal from R136 are discussed., Comment: 10+11 pages, 4+6 figures. Corresponding authors: L. Mohrmann, N. Komin
Published: 2024
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3. Testing the Molecular Cloud Paradigm for Ultra-High-Energy Gamma Ray Emission from the Direction of SNR G106.3+2.7

Author: Alfaro, R., Alvarez, C., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Babu, R., Belmont-Moreno, E., Bernal, A., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Cotti, U., Cotzomi, J., de León, S. Coutiño, De la Fuente, E., de León, C., Depaoli, D., Desiati, P., Di Lalla, N., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Engel, K., Ergin, T., Espinoza, C., Fan, K. L., Fang, K., Fraija, N., Fraija, S., García-González, J. A., Garfias, F., González, M. M., Goodman, J. A., Groetsch, S., Harding, J. P., Hernández-Cadena, S., Herzog, I., Hinton, J., Huang, D., Hueyotl-Zahuantitla, F., Humensky, T. B., Hüntemeyer, P., Kaufmann, S., Kieda, D., Lee, W. H., Lee, J., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Malone, K., Martinez, O., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Montes, J. A., Moreno, E., Mostafá, M., Nellen, L., Nisa, M. U., Olivera-Nieto, L., Omodei, N., Araujo, Y. Pérez, Pérez-Pérez, E. G., Rho, C. D., Rosa-González, D., Salazar, H., Salazar-Gallegos, D., Sandoval, A., Schneider, M., Serna-Franco, J., Smith, A. J., Son, Y., Springer, R. W., Tibolla, O., Tollefson, K., Torres, I., Torres-Escobedo, R., Turner, R., Ureña-Mena, F., Varela, E., Villaseñor, L., Wang, X., Wang, Z., Watson, I. J., Willox, E., Yu, S., Yun-Cárcamo, S., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Supernova remnants (SNRs) are believed to be capable of accelerating cosmic rays (CRs) to PeV energies. SNR G106.3+2.7 is a prime PeVatron candidate. It is formed by a head region, where the pulsar J2229+6114 and its boomerang-shaped pulsar wind nebula are located, and a tail region containing SN ejecta. The lack of observed gamma ray emission from the two regions of this SNR has made it difficult to assess which region would be responsible for the PeV CRs. We aim to characterize the very-high-energy (VHE, 0.1-100 TeV) gamma ray emission from SNR G106.3+2.7 by determining the morphology and spectral energy distribution of the region. This is accomplished using 2565 days of data and improved reconstruction algorithms from the HAWC Observatory. We also explore possible gamma ray production mechanisms for different energy ranges. Using a multi-source fitting procedure based on a maximum-likelihood estimation method, we evaluate the complex nature of this region. We determine the morphology, spectrum, and energy range for the source found in the region. Molecular cloud information is also used to create a template and evaluate the HAWC gamma ray spectral properties at ultra-high-energies (UHE, >56 TeV). This will help probe the hadronic nature of the highest-energy emission from the region. We resolve one extended source coincident with all other gamma ray observations of the region. The emission reaches above 100~TeV and its preferred log-parabola shape in the spectrum shows a flux peak in the TeV range. The molecular cloud template fit on the higher energy data reveals that the SNR's energy budget is fully capable of producing a purely hadronic source for UHE gamma rays.
Published: 2024
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4. Observation of the Galactic Center PeVatron Beyond 100 TeV with HAWC

Author: Albert, A., Alfaro, R., Alvarez, C., Andrés, A., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Babu, R., Belmont-Moreno, E., Bernal, A., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Cotti, U., Cotzomi, J., de León, S. Coutiño, De la Fuente, E., de León, C., Depaoli, D., Di Lalla, N., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Engel, K., Ergin, T., Espinoza, C., Fan, K. L., Fang, K., Fraija, N., Fraija, S., García-González, J. A., Garfias, F., Goksu, H., González, M. M., Goodman, J. A., Groetsch, S., Harding, J. P., Hernández-Cadena, S., Herzog, I., Hinton, J., Huang, D., Hueyotl-Zahuantitla, F., Humensky, T. B., Hüntemeyer, P., Iriarte, A., Kaufmann, S., Kieda, D., Lara, A., Lee, W. H., Lee, J., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Malone, K., Martinez, O., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Montes, J. A., Morales-Soto, J. A., Moreno, E., Mostafá, M., Najafi, M., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Olivera-Nieto, L., Omodei, N., Osorio-Archila, M., Araujo, Y. Pérez, Pérez-Pérez, E. G., Rho, C. D., Rosa-González, D., Ruiz-Velasco, E., Salazar, H., Salazar-Gallegos, D., Sandoval, A., Schneider, M., Schwefer, G., Serna-Franco, J., Smith, A. J., Son, Y., Springer, R. W., Tibolla, O., Tollefson, K., Torres, I., Torres-Escobedo, R., Turner, R., Ureña-Mena, F., Varela, E., Wang, X., Wang, Z., Watson, I. J., Willox, E., Wu, H., Yu, S., Yun-Cárcamo, S., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report an observation of ultra-high energy (UHE) gamma rays from the Galactic Center region, using seven years of data collected by the High-Altitude Water Cherenkov (HAWC) Observatory. The HAWC data are best described as a point-like source (HAWC J1746-2856) with a power-law spectrum ($\mathrm{d}N/\mathrm{d}E=\phi(E/26 \,\text{TeV})^{\gamma}$), where $\gamma=-2.88 \pm 0.15_{\text{stat}} - 0.1_{\text{sys}} $ and $\phi=1.5 \times 10^{-15}$ (TeV cm$^{2}$s)$^{-1}$ $\pm\, 0.3_{\text{stat}}\,^{+0.08_{\text{sys}}}_{-0.13_{\text{sys}}}$ extending from 6 to 114 TeV. We find no evidence of a spectral cutoff up to $100$ TeV using HAWC data. Two known point-like gamma-ray sources are spatially coincident with the HAWC gamma-ray excess: Sgr A$^{*}$ (HESS J1745-290) and the Arc (HESS J1746-285). We subtract the known flux contribution of these point sources from the measured flux of HAWC J1746-2856 to exclude their contamination and show that the excess observed by HAWC remains significant ($>$5$\sigma$) with the spectrum extending to $>$100 TeV. Our result supports that these detected UHE gamma rays can originate via hadronic interaction of PeV cosmic-ray protons with the dense ambient gas and confirms the presence of a proton PeVatron at the Galactic Center.
Published: 2024

5. Performance of the HAWC Observatory and TeV Gamma-Ray Measurements of the Crab Nebula with Improved Extensive Air Shower Reconstruction Algorithms

Author: Albert, A ., Alfaro, R., Alvarez, C., Andrés, A ., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Babu, R., Belmont-Moreno, E., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Cotti, U., Cotzomi, J., de León, S. Coutiño, De la Fuente, E., de León, C., Depaoli, D., Di Lalla, N., Hernandez, R. Diaz, Dingus, B. L ., DuVernois, M. A., Engel, K., Ergin, T., Espinoza, C ., Fan, K. L., Fang, K., Fraija, N., Fraija, S., García-González, J. A., Garfias, F., Goksu, H ., González, M. M., Goodman, J. A., Groetsch, S., Harding, J. P., Hernández-Cadena, S., Herzog, I., Hinton, J ., Huang, D., Hueyotl-Zahuantitla, F., Hüntemeyer, P., Iriarte, A., Kaufmann, S., Lara, A ., Lee, J., Vargas, H. León, Linnemann, J. T ., Longinotti, A. L., Luis-Raya, G., Malone, K., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Montes, J. A., Moreno, E., Mostafá, M., Nellen, L., Nisa, M. U ., Noriega-Papaqui, R ., Olivera-Nieto, L ., Omodei, N., Osorio, M., Araujo, Y. Pérez, Pérez-Pérez, E. G., Rho, C. D., Rosa-González, D., Ruiz-Velasco, E ., Salazar, H., Salazar-Gallegos, D., Sandoval, A., Schneider, M., Schwefer, G ., Serna-Franco, J., Smith, A. J., Son, Y., Springer, R. W ., Tibolla, O., Tollefson, K., Torres, I., Torres-Escobedo, R., Turner, R., Ureña-Mena, F., Varela, E ., Wang, X., Watson, I. J., Whitaker, K., Willox, E., Wu, H., Yu, S ., Yun-Cárcamo, S., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: The High-Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory located on the side of the Sierra Negra volcano in Mexico, has been fully operational since 2015. The HAWC collaboration has recently significantly improved their extensive-air-shower reconstruction algorithms, which has notably advanced the observatory performance. The energy resolution for primary gamma rays with energies below 1~TeV was improved by including a noise-suppression algorithm. Corrections have also been made to systematic errors in direction fitting related to the detector and shower plane inclinations, $\mathcal{O}(0.1^{\circ})$ biases in highly inclined showers, as well as enhancements to the core reconstruction. The angular resolution for gamma rays approaching the HAWC array from large zenith angles ($> 37^{\circ}$) has improved by a factor of four at the highest energies ($> 70$~TeV) as compared to previous reconstructions. The inclusion of a lateral distribution function fit to the extensive air shower footprint on the array to separate gamma-ray primaries from cosmic-ray ones, based on the resulting $\chi^{2}$ values, improved the background rejection performance at all inclinations. At large zenith angles, the improvement in significance is a factor of four compared to previous HAWC publications. These enhancements have been verified by observing the Crab Nebula, which is an overhead source for the HAWC Observatory. We show that the sensitivity to Crab-like point sources ($E^{-2.63}$) with locations overhead to 30$^{\circ}$ zenith is comparable or less than 10\% of the Crab Nebula's flux between 2 and 50~TeV. Thanks to these improvements, HAWC can now detect more sources, including the Galactic Center.
Published: 2024

6. Unveiling extended gamma-ray emission around HESS J1813-178

Author: Aharonian, F., Benkhali, F. Ait, Aschersleben, J., Ashkar, H., Backes, M., Baktash, A., Martins, V. Barbosa, Barnard, J., Batzofin, R., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Borowska, J., Bouyahiaoui, M., Breuhaus, M., Brose, R., Brun, F., Bruno, B., Bulik, T., Burger-Scheidlin, C., Caroff, S., Casanova, S., Cecil, R., Celic, J., Cerruti, M., Chambery, P., Chand, T., Chen, A., Chibueze, J., Chibueze, O., Cotter, G., Mbarubucyeye, J. Damascene, Djannati-Ataï, A., Dmytriiev, A., Doroshenko, V., Einecke, S., Ernenwein, J. -P., Feijen, K., Filipovic, M., Fontaine, G., Füßling, M., Funk, S., Gabici, S., Gallant, Y. A., Ghafourizadeh, S., Giavitt, G., Glawion, D., Glicenstein, J. F., Goswami, P., Grolleron, G., Grondin, M. -H., Hinton, J. A., Hofmann, W., Holch, T. L., Holler, M., Jamrozy, M., Jankowsky, F., Joshi, V., Jung-Richardt, I., Katarzyński, K., Khatoon, R., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Kosack, K., Kostunin, D., Kundu, A., Lang, R. G., Stum, S. Le, Leitl, F., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Mackey, J., Malyshev, D., Marandon, V., Marinos, P., Martí-Devesa, G., Marx, R., Mehta, A., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Murach, T., de Naurois, M., Niemiec, J., Noel, A. Priyana, O'Brien, P., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Prokhorov, D. A., Pühlhofer, G., Punch, M., Quirrenbach, A., Regeard, M., Reichherzer, P., Reimer, A., Reimer, O., Ren, H., Renaud, M., Reville, B., Rieger, F., Roellinghoff, G., Rudak, B., Sahakian, V., Salzmann, H., Sasaki, M., Schüssler, F., Schutte, H. M., Shapopi, J. N. S., Specovius, A., Spencer, S., Steenkamp, R., Steinmassl, S., Steppa, C., Sushch, I., Suzuki, H., Takahashi, T., Tanaka, T., Terrier, R., Tluczykont, M., Tsuji, N., Unbehaun, T., van Eldik, C., Vecchi, M., Veh, J., Venter, C., Vink, J., Wach, T., Wagner, S. J., Wierzcholska, A., Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zouari, S., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: HESS J1813$-$178 is a very-high-energy $\gamma$-ray source spatially coincident with the young and energetic pulsar PSR J1813$-$1749 and thought to be associated with its pulsar wind nebula (PWN). Recently, evidence for extended high-energy emission in the vicinity of the pulsar has been revealed in the Fermi Large Area Telescope (LAT) data. This motivates revisiting the HESS J1813$-$178 region, taking advantage of improved analysis methods and an extended data set. Using data taken by the High Energy Stereoscopic System (H.E.S.S.) experiment and the Fermi-LAT, we aim to describe the $\gamma$-ray emission in the region with a consistent model, to provide insights into its origin. We performed a likelihood-based analysis on 32 hours of H.E.S.S. data and 12 years of Fermi-LAT data and fit a spectro-morphological model to the combined datasets. These results allowed us to develop a physical model for the origin of the observed $\gamma$-ray emission in the region. In addition to the compact very-high-energy $\gamma$-ray emission centered on the pulsar, we find a significant yet previously undetected component along the Galactic plane. With Fermi-LAT data, we confirm extended high-energy emission consistent with the position and elongation of the extended emission observed with H.E.S.S. These results establish a consistent description of the emission in the region from GeV energies to several tens of TeV. This study suggests that HESS J1813$-$178 is associated with a $\gamma$-ray PWN powered by PSR J1813$-$1749. A possible origin of the extended emission component is inverse Compton emission from electrons and positrons that have escaped the confines of the pulsar and form a halo around the PWN., Comment: 13+5 pages, 13+11 figures. Accepted for publication in A&A. Corresponding authors: T.Wach, A.Mitchell, V.Joshi, P.Chamb\'ery
Published: 2024
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7. Spectrum and extension of the inverse-Compton emission of the Crab Nebula from a combined Fermi-LAT and H.E.S.S. analysis

Author: Aharonian, F., Benkhali, F. Ait, Aschersleben, J., Ashkar, H., Backes, M., Baktash, A., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Borowska, J., Bradascio, F., Breuhaus, M., Brose, R., Brown, A., Brun, F., Bruno, B., Bulik, T., Burger-Scheidlin, C., Bylund, T., Caroff, S., Casanova, S., Cecil, R., Celic, J., Cerruti, M., Chambery, P., Chand, T., Chandra, S., Chen, A., Chibueze, J., Chibueze, O., Cotter, G., Cristofari, P., Devin, J., Djannati-Ataï, A., Djuvsland, J., Dmytriiev, A., Einecke, S., Ernenwein, J. -P., Fegan, S., Feijen, K., Filipović, M., Fontaine, G., Füßling, M., Funk, S., Gabici, S., Gallant, Y. A., Giavitto, G., Glawion, D., Glicenstein, J. F., Glombitza, J., Goswami, P., Grolleron, G., Grondin, M. -H., Haerer, L., Hinton, J. A., Hofmann, W., Holch, T. L., Holler, M., Horns, D., Jamrozy, M., Jankowsky, F., Joshi, V., Kasai, E., Katarzyński, K., Khatoon, R., Khélifi, B., Kluźniak, W., Komin, Nu., Kosack, K., Kostunin, D., Kundu, A., Lang, R. G., Stum, S. Le, Leitl, F., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Luashvili, A., Mackey, J., Malyshev, D., Marandon, V., Marinos, P., Martí-Devesa, G., Marx, R., Mehta, A., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Murach, T., de Naurois, M., Niemiec, J., O'Brien, P., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Prokhorov, D. A., Pühlhofer, G., Punch, M., Quirrenbach, A., Regeard, M., Reichherzer, P., Reimer, A., Reimer, O., Ren, H., Renaud, M., Reville, B., Rieger, F., Roellinghoff, G., Rudak, B., Sahakian, V., Salzmann, H., Sasaki, M., Schüssler, F., Schutte, H. M., Shapopi, J. N. S., Specovius, A., Spencer, S., Stawarz, Ł., Steenkamp, R., Steinmassl, S., Steppa, C., Streil, K., Sushch, I., Suzuki, H., Takahashi, T., Tanaka, T., Terrier, R., Tluczykont, M., Tsuji, N., Unbehaun, T., van Eldik, C., Vecchi, M., Veh, J., Venter, C., Vink, J., Wach, T., Wagner, S. J., Wierzcholska, A., Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zech, A., Zouari, S., Żywucka, N., and Harding, A.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The Crab Nebula is a unique laboratory for studying the acceleration of electrons and positrons through their non-thermal radiation. Observations of very-high-energy $\gamma$ rays from the Crab Nebula have provided important constraints for modelling its broadband emission. We present the first fully self-consistent analysis of the Crab Nebula's $\gamma$-ray emission between 1 GeV and $\sim$100 TeV, that is, over five orders of magnitude in energy. Using the open-source software package Gammapy, we combined 11.4 yr of data from the Fermi Large Area Telescope and 80 h of High Energy Stereoscopic System (H.E.S.S.) data at the event level and provide a measurement of the spatial extension of the nebula and its energy spectrum. We find evidence for a shrinking of the nebula with increasing $\gamma$-ray energy. Furthermore, we fitted several phenomenological models to the measured data, finding that none of them can fully describe the spatial extension and the spectral energy distribution at the same time. Especially the extension measured at TeV energies appears too large when compared to the X-ray emission. Our measurements probe the structure of the magnetic field between the pulsar wind termination shock and the dust torus, and we conclude that the magnetic field strength decreases with increasing distance from the pulsar. We complement our study with a careful assessment of systematic uncertainties., Comment: 18+6 pages, 15+2 figures. Accepted for publication in A&A. Corresponding authors: M. Meyer, L. Mohrmann, T. Unbehaun. v2: after A&A language editing
Published: 2024
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8. Dark Matter Line Searches with the Cherenkov Telescope Array

Author: Abe, S., Abhir, J., Abhishek, A., Acero, F., Acharyya, A., Adam, R., Aguasca-Cabot, A., Agudo, I., Aguirre-Santaella, A., Alfaro, J., Alfaro, R., Alvarez-Crespo, N., Batista, R. Alves, Amans, J. -P., Amato, E., Ambrosi, G., Angel, L., Aramo, C., Arcaro, C., Arnesen, T. T. H., Arrabito, L., Asano, K., Ascasibar, Y., Aschersleben, J., Ashkar, H., Backes, M., Baktash, A., Balazs, C., Balbo, M., Larriva, A. Baquero, Martins, V. Barbosa, de Almeida, U. Barres, Barrio, J. A., Batković, I., Batzofin, R., Baxter, J., González, J. Becerra, Beck, G., Benbow, W., Berge, D., Bernardini, E., Bernete, J., Bernlöhr, K., Berti, A., Bertucci, B., Bhattacharjee, P., Bhattacharyya, S., Bigongiari, C., Biland, A., Bissaldi, E., Biteau, J., Blanch, O., Blazek, J., Bocchino, F., Boisson, C., Bolmont, J., Bonnoli, G., Bonollo, A., Bordas, P., Bosnjak, Z., Bottacini, E., Böttcher, M., Bringmann, T., Bronzini, E., Brose, R., Brown, A. M., Brunelli, G., Bulgarelli, A., Bulik, T., Burelli, I., Burmistrov, L., Burton, M., Buscemi, M., Bylund, T., Cailleux, J., Campoy-Ordaz, A., Cantlay, B. K., Capasso, G., Caproni, A., Capuzzo-Dolcetta, R., Caraveo, P., Caroff, S., Carosi, A., Carosi, R., Carquin, E., Carrasco, M. -S., Cassol, F., Castaldini, L., Castrejon, N., Castro-Tirado, A. J., Cerasole, D., Cerruti, M., Chadwick, P. M., Chaty, S., Chen, A. W., Chernyakova, M., Chiavassa, A., Chudoba, J., Chytka, L., Cicciari, G. M., Cifuentes, A., Araujo, C. H. Coimbra, Colapietro, M., Conforti, V., Conte, F., Contreras, J. L., Costa, A., Costantini, H., Cotter, G., Cristofari, P., Cuevas, O., Curtis-Ginsberg, Z., D'Amico, G., D'Ammando, F., Dai, S., Dalchenko, M., Dazzi, F., De Angelis, A., de Lavergne, M. de Bony, De Caprio, V., Pino, E. M. de Gouveia Dal, De Lotto, B., De Lucia, M., de Menezes, R., de Naurois, M., de Souza, V., del Peral, L., del Valle, M. V., Giler, A. G. Delgado, Mengual, J. Delgado, Delgado, C., Dell'aiera, M., della Volpe, D., Depaoli, D., Di Girolamo, T., Di Piano, A., Di Pierro, F., Di Tria, R., Di Venere, L., Díaz, C., Diebold, S., Dinesh, A., Djuvsland, J., Dominik, R. M., Prester, D. Dominis, Donini, A., Dorner, D., Dörner, J., Doro, M., Dournaux, J. -L., Duangchan, C., Dubos, C., Ducci, L., Dwarkadas, V. V., Ebr, J., Eckner, C., Egberts, K., Einecke, S., Elsässer, D., Emery, G., Errando, M., Escanuela, C., Escarate, P., Godoy, M. Escobar, Escudero, J., Esposito, P., Ettori, S., Falceta-Goncalves, D., Fedorova, E., Fegan, S., Feng, Q., Ferrand, G., Ferrarotto, F., Fiandrini, E., Fiasson, A., Filipovic, M., Fioretti, V., Fiori, M., Foffano, L., Guiteras, L. Font, Fontaine, G., Fröse, S., Fukazawa, Y., Fukui, Y., Furniss, A., Galanti, G., Galaz, G., Galelli, C., Gallozzi, S., Gammaldi, V., Garczarczyk, M., Gasbarra, C., Gasparrini, D., Ghalumyan, A., Gianotti, F., Giarrusso, M., Paiva, J. G. Giesbrecht Formiga, Giglietto, N., Giordano, F., Giuffrida, R., Glicenstein, J. -F., Glombitza, J., Goldoni, P., González, J. M., González, M. M., Coelho, J. Goulart, Gradetzke, T., Granot, J., Grasso, D., Grau, R., Gréaux, L., Green, D., Green, J. G., Grolleron, G., Guedes, L. M. V., Gueta, O., Hackfeld, J., Hadasch, D., Hamal, P., Hanlon, W., Hara, S., Harvey, V. M., Hassan, T., Hayashi, K., Heß, B., Heckmann, L., Heller, M., Cadena, S. Hernández, Hervet, O., Hinton, J., Hiroshima, N., Hnatyk, B., Hnatyk, R., Hofmann, W., Holder, J., Horan, D., Horvath, P., Hovatta, T., Hrabovsky, M., Hrupec, D., Iarlori, M., Inada, T., Incardona, F., Inoue, S., Inoue, Y., Iocco, F., Iori, M., Ishio, K., Jamrozy, M., Janecek, P., Jankowsky, F., Jean, P., Quiles, J. Jimenez, Jin, W., Juramy-Gilles, C., Jurysek, J., Kagaya, M., Kalekin, O., Karas, V., Katagiri, H., Kataoka, J., Kaufmann, S., Kazanas, D., Kerszberg, D., Kieda, D. B., Kleiner, T., Kluge, G., Kobayashi, Y., Kohri, K., Komin, N., Kornecki, P., Kosack, K., Kowal, G., Kubo, H., Kushida, J., La Barbera, A., La Palombara, N., Láinez, M., Lamastra, A., Lapington, J., Laporte, P., Lazarević, S., Lazendic-Galloway, J., Lemoine-Goumard, M., Lenain, J. -P., Leone, F., Leonora, E., Leto, G., Lindfors, E., Linhoff, M., Liodakis, I., Lipniacka, A., Lombardi, S., Longo, F., López-Coto, R., López-Moya, M., López-Oramas, A., Loporchio, S., Bahilo, J. Lozano, Luque-Escamilla, P. L., Macias, O., Majumdar, P., Mallamaci, M., Malyshev, D., Mandat, D., Manicò, G., Mariotti, M., Márquez, I., Marquez, P., Marsella, G., Martí, J., Martínez, G. A., Martínez, M., Martinez, O., Marty, C., Mas-Aguilar, A., Mastropietro, M., Mazin, D., Menchiari, S., Mestre, E., Meunier, J. -L., Meyer, D. M. -A., Meyer, M., Miceli, D., Miceli, M., Michailidis, M., Michałowski, J., Miener, T., Miranda, J. M., Mitchell, A., Mizote, M., Mizuno, T., Moderski, R., Molero, M., Molfese, C., Molina, E., Montaruli, T., Moralejo, A., Morcuende, D., Morselli, A., Moulin, E., Zamanillo, V. Moya, Munari, K., Murach, T., Muraczewski, A., Muraishi, H., Nakamori, T., Nayak, A., Nemmen, R., Neto, J. P., Nickel, L., Niemiec, J., Nieto, D., Rosillo, M. Nievas, Nikołajuk, M., Nikolić, L., Nishijima, K., Noda, K., Nosek, D., Novotny, V., Nozaki, S., Ohishi, M., Ohtani, Y., Okumura, A., Olive, J. -F., Ong, R. A., Orienti, M., Orito, R., Orlandini, M., Orlando, E., Orlando, S., Ostrowski, M., Otero-Santos, J., Oya, I., Pagano, I., Pagliaro, A., Palatiello, M., Panebianco, G., Paneque, D., Pantaleo, F. R., Paredes, J. M., Parmiggiani, N., Patricelli, B., Pe'er, A., Pech, M., Pecimotika, M., Pensec, U., Peresano, M., Pérez-Romero, J., Persic, M., Peters, K. P., Petruk, O., Piano, G., Pierre, E., Pietropaolo, E., Pihet, M., Pinchbeck, L., Pirola, G., Pittori, C., Plard, C., Podobnik, F., Pohl, M., Pollet, V., Ponti, G., Prandini, E., Principe, G., Priyadarshi, C., Produit, N., Prouza, M., Pueschel, E., Pühlhofer, G., Pumo, M. L., Queiroz, F., Quirrenbach, A., Rainò, S., Rando, R., Razzaque, S., Regeard, M., Reimer, A., Reimer, O., Reisenegger, A., Rhode, W., Ribeiro, D., Ribó, M., Ricci, C., Richtler, T., Rico, J., Rieger, F., Riitano, L., Rizi, V., Roache, E., Fernandez, G. Rodriguez, Frías, M. D. Rodríguez, Rodríguez-Vázquez, J. J., Romano, P., Romeo, G., Rosado, J., de Leon, A. Rosales, Rowell, G., Rudak, B., Ruiter, A. J., Rulten, C. B., Sadeh, I., Saha, L., Saito, T., Salzmann, H., Sánchez-Conde, M., Sandaker, H., Sangiorgi, P., Sano, H., Santander, M., Santos-Lima, R., Sapienza, V., Šarić, T., Sarkar, A., Sarkar, S., Saturni, F. G., Savarese, S., Scherer, A., Schiavone, F., Schipani, P., Schleicher, B., Schovanek, P., Schubert, J. L., Schwanke, U., Arroyo, M. Seglar, Seitenzahl, I. R., Sergijenko, O., Servillat, M., Siegert, T., Siejkowski, H., Siqueira, C., Sliusar, V., Slowikowska, A., Sol, H., Spencer, S. T., Spiga, D., Stamerra, A., Stanič, S., Starecki, T., Starling, R., Stawarz, Ł., Steppa, C., Hatlen, E. Sæther, Stolarczyk, T., Strišković, J., Suda, Y., Świerk, P., Tajima, H., Tak, D., Takahashi, M., Takeishi, R., Tavernier, T., Tejedor, L. A., Terauchi, K., Teshima, M., Testa, V., Tian, W. W., Tibaldo, L., Tibolla, O., Peixoto, C. J. Todero, Torradeflot, F., Torres, D. F., Tosti, G., Tothill, N., Toussenel, F., Tramacere, A., Travnicek, P., Tripodo, G., Trois, A., Truzzi, S., Tutone, A., Vaclavek, L., Vacula, M., Vallania, P., Vallés, R., van Eldik, C., van Scherpenberg, J., Vandenbroucke, J., Vassiliev, V., Acosta, M. Vázquez, Vecchi, M., Ventura, S., Vercellone, S., Verna, G., Viana, A., Viaux, N., Vigliano, A., Vignatti, J., Vigorito, C. F., Villanueva, J., Visentin, E., Vitale, V., Vodeb, V., Voisin, V., Voitsekhovskyi, V., Vorobiov, S., Voutsinas, G., Vovk, I., Vuillaume, T., Wagner, S. J., Walter, R., White, M., White, R., Wierzcholska, A., Will, M., Williams, D. A., Wohlleben, F., Wolter, A., Yamamoto, T., Yang, L., Yoshida, T., Yoshikoshi, T., Zaharijas, G., Zampieri, L., Sanchez, R. Zanmar, Zavrtanik, D., Zavrtanik, M., Zdziarski, A. A., Zech, A., Zhang, W., Zhdanov, V. I., Ziętara, K., Živec, M., and Zuriaga-Puig, J.
Subjects: High Energy Physics - Phenomenology, Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract: Monochromatic gamma-ray signals constitute a potential smoking gun signature for annihilating or decaying dark matter particles that could relatively easily be distinguished from astrophysical or instrumental backgrounds. We provide an updated assessment of the sensitivity of the Cherenkov Telescope Array (CTA) to such signals, based on observations of the Galactic centre region as well as of selected dwarf spheroidal galaxies. We find that current limits and detection prospects for dark matter masses above 300 GeV will be significantly improved, by up to an order of magnitude in the multi-TeV range. This demonstrates that CTA will set a new standard for gamma-ray astronomy also in this respect, as the world's largest and most sensitive high-energy gamma-ray observatory, in particular due to its exquisite energy resolution at TeV energies and the adopted observational strategy focussing on regions with large dark matter densities. Throughout our analysis, we use up-to-date instrument response functions, and we thoroughly model the effect of instrumental systematic uncertainties in our statistical treatment. We further present results for other potential signatures with sharp spectral features, e.g.~box-shaped spectra, that would likewise very clearly point to a particle dark matter origin., Comment: 44 pages JCAP style (excluding author list and references), 19 figures; minor changes to match published version
Published: 2024
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9. Acceleration and transport of relativistic electrons in the jets of the microquasar SS 433

Author: Aharonian, F., Benkhali, F. Ait, Aschersleben, J., Ashkar, H., Backes, M., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Borowska, J., Bouyahiaou, M., Breuhau, M., Brose, R., Brown, A. M., Brun, F., Bruno, B., Bulik, T., Burger-Scheidlin, C., Caroff, S., Casanova, S., Cecil, R., Celic, J., Cerruti, M., Chand, T., Chandra, S., Chen, A., Chibueze, J., Chibueze, O., Cotter, G., Dai, S., Mbarubucyeye, J. Damascene, Djannati-Ataï, A., Dmytriiev, A., Doroshenko, V., Egberts, K., Einecke, S., Ernenwein, J. -P., Filipovic, M., Fontaine, G., Funk, S., Gabici, S., Ghafourizadeh, S., Giavitto, G., Glawion, D., Glicenstein, J. F., Grolleron, G., Haerer, L., Hinton, J. A., Hofmann, W., Holch, T. L., Holler, M., Horns, D., Jamrozy, M., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzyński, K., Khatoon, R., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Kosack, K., Kostunin, D., Kundu, A., Lang, R. G., Stum, S. Le, Leitl, F., Lemière, A., Lenain, J. -P., Leuschner, F., Lohse, T., Luashvili, A., Mackey, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Martí-Devesa, G., Marx, R., Mehta, A., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Murach, T., Nakashima, K., de Naurois, M., Niemiec, J., Noel, A. Priyana, Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Prokhorov, D. A., Pühlhofer, G., Punch, M., Quirrenbach, A., Reichherzer, P., Reimer, A., Reimer, O., Ren, H., Renaud, M., Reville, B., Rieger, F., Rowell, G., Rudak, B., Ricarte, H. Rueda, Ruiz-Velasco, E., Sahakian, V., Salzman, H., Santangelo, A., Sasaki, M., Schäfer, J., Schüssler, F., Schwanke, U., Shapopi, J. N. S., Sol, H., Specovius, A., Spencer, S., Stawarz, Ł., Steenkamp, R., Steinmassl, S., Steppa, C., Streil, K., Sushch, I., Suzuki, H., Takahashi, T., Tanaka, T., Taylor, A. M., Terrier, R., Tsirou, M., Tsuji, N., Unbehaun, T., van Eldik, C., Vecchi, M., Veh, J., Venter, C., Vink, J., Wach, T., Wagner, S. J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zech, A., Zouari, S., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: SS 433 is a microquasar, a stellar binary system with collimated relativistic jets. We observed SS 433 in gamma rays using the High Energy Stereoscopic System (H.E.S.S.), finding an energy-dependent shift in the apparent position of the gamma-ray emission of the parsec-scale jets. These observations trace the energetic electron population and indicate the gamma rays are produced by inverse-Compton scattering. Modelling of the energy-dependent gamma-ray morphology constrains the location of particle acceleration and requires an abrupt deceleration of the jet flow. We infer the presence of shocks on either side of the binary system at distances of 25 to 30 parsecs and conclude that self-collimation of the precessing jets forms the shocks, which then efficiently accelerate electrons., Comment: Submitted 20th Apr. 2023, published 25th January 2024 (accepted version)
Published: 2024
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10. Discovery of a Radiation Component from the Vela Pulsar Reaching 20 Teraelectronvolts

Author: Collaboration, The H. E. S. S., Aharonian, F., Benkhali, F. Ait, Aschersleben, J., Ashkar, H., Backes, M., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Borowska, J., Bradascio, F., Breuhaus, M., Brose, R., Brun, F., Bruno, B., Bulik, T., Burger-Scheidlin, C., Bylund, T., Cangemi, F., Caroff, S., Casanova, S., Celic, J., Cerruti, M., Chand, T., Chandra, S., Chen, A., Chibueze, O., Cotter, G., Mbarubucyeye, J. Damascene, Djannati-Ataï, A., Dmytriiev, A., Egberts, K., Ernenwein, J. -P., Feijen, K., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Füßling, M., Funk, S., Gabici, S., Gallant, Y. A., Ghafourizadeh, S., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Goswami, P., Grolleron, G., Grondin, M. -H., Haerer, L., Haupt, M., Hinton, J. A., Hofmann, W., Holch, T. L., Holler, M., Horns, D., Huang, Zhiqiu, Jamrozy, M., Jankowsky, F., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzyński, K., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Kosack, K., Kostunin, D., Lang, R. G., Stum, S. Le, Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Marinos, P., Martí-Devesa, G., Marx, R., Maurin, G., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Muller, J., Murach, T., Nakashima, K., de Naurois, M., Niemiec, J., Noel, A. Priyana, OBrien, P., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Pita, S., Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Reichherzer, P., Reimer, A., Reimer, O., Renaud, M., Rieger, F., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Schüssler, F., Schwanke, U., Shapopi, J. N. S., Sinha, A., Sol, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, L., Steenkamp, R., Steinmassl, S., Steppa, C., Sushch, I., Suzuki, H., Takahashi, T., Tanaka, T., Tavernier, T., Terrier, R., Thorpe-Morgan, C., Tluczykont, M., Tsirou, M., Tsuji, N., van Eldik, C., Vecchi, M., Veh, J., Venter, C., Vink, J., Wagner, S. J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yassin, H., Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zouari, S., Żywucka, N., Zanin, R., Kerr, M., Johnston, S., Shannon, R. M., and Smith, D. A.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Gamma-ray observations have established energetic isolated pulsars as outstanding particle accelerators and antimatter factories in the Galaxy. There is, however, no consensus regarding the acceleration mechanisms and the radiative processes at play, nor the locations where these take place. The spectra of all observed gamma-ray pulsars to date show strong cutoffs or a break above energies of a few gigaelectronvolt (GeV). Using the H.E.S.S. array of Cherenkov telescopes, we discovered a novel radiation component emerging beyond this generic GeV cutoff in the Vela pulsar's broadband spectrum. The extension of gamma-ray pulsation energies up to at least 20 teraelectronvolts (TeV) shows that Vela pulsar can accelerate particles to Lorentz factors higher than $4\times10^7$. This is an order of magnitude larger than in the case of the Crab pulsar, the only other pulsar detected in the TeV energy range. Our results challenge the state-of-the-art models for high-energy emission of pulsars while providing a new probe, i.e. the energetic multi-TeV component, for constraining the acceleration and emission processes in their extreme energy limit., Comment: 38 pages, 6 figures. This preprint has not undergone peer review or any post-submission improvements or corrections. The Version of Record of this article is published in Nature Astronomy, Nat Astron (2023), and is available online at https://doi.org/10.1038/s41550-023-02052-3
Published: 2023
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11. HAWC Study of Very-High-Energy $\gamma$-ray Spectrum of HAWC J1844-034

Author: HAWC Collaboration, Albert, A., Alvarez, C., Rojas, D. Avila, Solares, H. A. Ayala, Babu, R., Belmont-Moreno, E., Breuhaus, M., Capistrán, T., Carramiñana, A., Casanova, S., Cotzomi, J., de León, S. Coutiño, De la Fuente, E., Depaoli, D., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Durocher, M., Engel, K., Espinoza, C., Fan, K. L., Fang, K., Fraija, N., García-González, J. A., González, M. M., Goodman, J. A., Groetsch, S., Harding, J. P., Herzog, I., Hinton, J., Huang, D., Hueyotl-Zahuantitla, F., Humensky, T. B., Hüntemeyer, P., Joshi, V., Kaufmann, S., Lee, J., Vargas, H. León, Longinotti, A. L., Luis-Raya, G., Malone, K., Martinez, O., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nellen, L., Noriega-Papaqui, R., Olivera-Nieto, L., Omodei, N., Pérez-Pérez, E. G., Rho, C. D., Rosa-González, D., Ruiz-Velasco, E., Salazar, H., Salazar-Gallegos, D., Sandoval, A., Schneider, M., Serna-Franco, J., Smith, A. J., Son, Y., Springer, R. W., Tibolla, O., Tollefson, K., Torres, I., Torres-Escobedo, R., Turner, R., Ureña-Mena, F., Varela, E., Villaseñor, L., Wang, X., Watson, I. J., Willox, E., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Recently, the region surrounding eHWC J1842-035 has been studied extensively by gamma-ray observatories due to its extended emission reaching up to a few hundred TeV and potential as a hadronic accelerator. In this work, we use 1,910 days of cumulative data from the High Altitude Water Cherenkov (HAWC) observatory to carry out a dedicated systematic source search of the eHWC J1842-035 region. During the search we have found three sources in the region, namely, HAWC J1844-034, HAWC J1843-032, and HAWC J1846-025. We have identified HAWC J1844-034 as the extended source that emits photons with energies up to 175 TeV. We compute the spectrum for HAWC J1844-034 and by comparing with the observational results from other experiments, we have identified HESS J1843-033, LHAASO J1843-0338, and TASG J1844-038 as very-high-energy gamma-ray sources with a matching origin. Also, we present and use the multi-wavelength data to fit the hadronic and leptonic particle spectra. We have identified four pulsar candidates in the nearby region from which PSR J1844-0346 is found to be the most likely candidate due to its proximity to HAWC J1844-034 and the computed energy budget. We have also found SNR G28.6-0.1 as a potential counterpart source of HAWC J1844-034 for which both leptonic and hadronic scenarios are feasible., Comment: 13 pages, 9 figures, published in ApJ
Published: 2023
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12. Multiwavelength Observations of the Blazar PKS 0735+178 in Spatial and Temporal Coincidence with an Astrophysical Neutrino Candidate IceCube-211208A

Author: Acharyya, A., Adams, C. B., Archer, A., Bangale, P., Bartkoske, J. T., Batista, P., Benbow, W., Brill, A., Buckley, J. H., Christiansen, J. L., Chromey, A. J., Errando, M., Falcone, A., Feng, Q., Foote, G. M., Fortson, L., Furniss, A., Gallagher, G., Hanlon, W., Hanna, D., Hervet, O., Hinrichs, C. E., Hoang, J., Holder, J., Humensky, T. B., Jin, W., Kaaret, P., Kertzman, M., Kherlakian, M., Kieda, D., Kleiner, T. K., Korzoun, N., Kumar, S., Lang, M. J., Lundy, M., Maier, G., McGrath, C. E, Millard, M. J., Millis, J., Mooney, C. L., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Pohl, M., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Ribeiro, D., Roache, E., Sadeh, I., Sadun, A. C., Saha, L., Santander, M., Sembroski, G. H., Shang, R., Splettstoesser, M., Talluri, A. Kaushik, Tucci, J. V., Vassiliev, V. V., Weinstein, A., Williams, D. A., Wong, S. L., Woo, J., Aharonian, F., Aschersleben, J., Backes, M., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernlohr, K., Bi, B., Bottcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Borowska, J., Bouyahiaoui, M., Bradascio, F., Breuhaus, M., Brose, R., Brun, F., Bruno, B., Bulik, T., Burger-Scheidlin, C., Caroff, S., Casanova, S., Cecil, R., Celic, J., Cerruti, M., Chand, T., Chandra, S., Chen, A., Chibueze, J., Chibueze, O., Cotter, G., Dai, S., Mbarubucyeye, J. Damascene, Djannati-Atai, A., Dmytriiev, A., Doroshenko, V., Einecke, S., Ernenwein, J. -P., de Clairfontaine, G. Fichet, Filipovic, M., Fontaine, G., Fussling, M., Funk, S., Gabici, S., Ghafourizadeh, S., Giavitto, G., Glawion, D., Glicenstein, J. F., Goswami, P., Grolleron, G., Haerer, L., Hinton, J. A., Holch, T. L., Holler, M., Horns, D., Jamrozy, M., Jankowsky, F., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzynski, K., Khatoon, R., Khelifi, B., Klepser, S., Kluzniak, W., Kosack, K., Kostunin, D., Lang, R. G., Stum, S. Le, Lemiere, A., Lenain, J. P., Leuschner, F., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Marti-Devesa, G., Marx, R., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Murach, T., Nakashima, K., Niemiec, J., Noel, A. Priyana, O'Brien, P., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Peron, G., Prokhorov, D. A., Puhlhofer, G., Punch, M., Quirrenbach, A., Reichherzer, P., Reimer, A., Reimer, O., Ren, H., Renaud, M., Rieger, F., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Santangelo, A., Sasaki, M., Schafer, J., Schussler, F., Schutte, H. M., Schwanke, U., Shapopi, J. N. S., Specovius, A., Spencer, S., Stawarz, L., Steenkamp, R., Steinmassl, S., Sushch, I., Suzuki, H., Takahashi, T., Tanaka, T., Terrier, R., van Eldik, C., Vecchi, M., Veh, J., Venter, C., Vink, J., White, R., Wierzcholska, A., Wong, Yu Wun, Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zech, A., Zouari, S., Zywucka, N., and Mori, K.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on multiwavelength target-of-opportunity observations of the blazar PKS 0735+178, located 2.2$^\circ$ away from the best-fit position of the IceCube neutrino event IceCube-211208A detected on December 8, 2021. The source was in a high-flux state in the optical, ultraviolet, X-ray, and GeV gamma-ray bands around the time of the neutrino event, exhibiting daily variability in the soft X-ray flux. The X-ray data from Swift-XRT and NuSTAR characterize the transition between the low-energy and high-energy components of the broadband spectral energy distribution (SED), and the gamma-ray data from Fermi -LAT, VERITAS, and H.E.S.S. require a spectral cut-off near 100 GeV. Both X-ray and gamma-ray measurements provide strong constraints on the leptonic and hadronic models. We analytically explore a synchrotron self-Compton model, an external Compton model, and a lepto-hadronic model. Models that are entirely based on internal photon fields face serious difficulties in matching the observed SED. The existence of an external photon field in the source would instead explain the observed gamma-ray spectral cut-off in both leptonic and lepto-hadronic models and allow a proton jet power that marginally agrees with the Eddington limit in the lepto-hadronic model. We show a numerical lepto-hadronic model with external target photons that reproduces the observed SED and is reasonably consistent with the neutrino event despite requiring a high jet power., Comment: 21 pages, 3 figures, accepted by ApJ
Published: 2023

13. Constraining the cosmic-ray pressure in the inner Virgo Cluster using H.E.S.S. observations of M 87

Author: Collaboration, H. E. S. S., Aharonian, F., Benkhali, F. Ait, Arcaro, C., Aschersleben, J., Backes, M., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., Borowska, J., Bradascio, F., Breuhaus, M., Brose, R., Brun, F., Bruno, B., Bulik, T., Burger-Scheidlin, C., Bylund, T., Caroff, S., Casanova, S., Cecil, R., Celic, J., Cerruti, M., Chand, T., Chandra, S., Chen, A., Chibueze, J., Chibueze, O., Cotter, G., Mbarubucyeye, J. Damascene, Djannati-Ataï, A., Egberts, K., Ernenwein, J. -P., de Clairfontaine, G. Fichet, Filipovic, M., Fontaine, G., Füßling, M., Funk, S., Gabici, S., Ghafourizadeh, S., Giavitto, G., Glawion, D., Glicenstein, J. F., Goswami, P., Grolleron, G., Grondin, M. -H., Haerer, L., Haupt, M., Hermann, G., Hinton, J. A., Holch, T. L., Horns, D., Jamrozy, M., Jankowsky, F., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzyński, K., Khatoon, R., Khélifi, B., Kluźniak, W., Komin, Nu., Kosack, K., Kostunin, D., Lang, R. G., Stum, S. Le, Leitl, F., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Marinos, P., Martí-Devesa, G., Marx, R., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Muller, J., Nakashima, K., de Naurois, M., Niemiec, J., Noel, A. Priyana, O'Brien, P., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Panny, S., Panter, M., Parsons, R. D., Peron, G., Pita, S., Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Quirrenbach, A., Reichherzer, P., Reimer, A., Reimer, O., Renaud, M., Rieger, F., Rowell, G., Rudak, B., Velasco, E. Ruiz, Sahakian, V., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Schäfer, J., Schüssler, F., Schwanke, U., Shapopi, J. N. S., Sol, H., Specovius, A., Spencer, S., Stawarz, Ł., Steenkamp, R., Steinmassl, S., Steppa, C., Sushch, I., Suzuki, H., Takahashi, T., Tanaka, T., Taylor, A. M., Terrier, R., Tsirou, M., Tsuji, N., Uchiyama, Y., van Eldik, C., van Soelen, B., Vecchi, M., Veh, J., Venter, C., Vink, J., Wach, T., Wagner, S. J., White, R., Wierzcholska, A., Wong, Yu Wun, Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zech, A., Zouari, S., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract: The origin of the gamma-ray emission from M87 is currently a matter of debate. This work aims to localize the VHE (100 GeV-100 TeV) gamma-ray emission from M87 and probe a potential extended hadronic emission component in the inner Virgo Cluster. The search for a steady and extended gamma-ray signal around M87 can constrain the cosmic-ray energy density and the pressure exerted by the cosmic rays onto the intra-cluster medium, and allow us to investigate the role of the cosmic rays in the active galactic nucleus feedback as a heating mechanism in the Virgo Cluster. H.E.S.S. telescopes are sensitive to VHE gamma rays and have been utilized to observe M87 since 2004. We utilized a Bayesian block analysis to identify M87 emission states with H.E.S.S. observations from 2004 until 2021, dividing them into low, intermediate, and high states. Because of the causality argument, an extended ($\gtrsim$kpc) signal is allowed only in steady emission states. Hence, we fitted the morphology of the 120h low state data and found no significant gamma-ray extension. Therefore, we derived for the low state an upper limit of 58"(corresponding to $\approx$4.6kpc) in the extension of a single-component morphological model described by a rotationally symmetric 2D Gaussian model at 99.7% confidence level. Our results exclude the radio lobes ($\approx$30 kpc) as the principal component of the VHE gamma-ray emission from the low state of M87. The gamma-ray emission is compatible with a single emission region at the radio core of M87. These results, with the help of two multiple-component models, constrain the maximum cosmic-ray to thermal pressure ratio $X_{{CR,max.}}$$\lesssim$$0.32$ and the total energy in cosmic-ray protons (CRp) to $U_{CR}$$\lesssim$5$\times10^{58}$ erg in the inner 20kpc of the Virgo Cluster for an assumed CRp power-law distribution in momentum with spectral index $\alpha_{p}$=2.1., Comment: 15 pages, 7 figures. Accepted for publication in A&A. Corresponding authors: Victor Barbosa Martins, Stefan Ohm, Cornelia Arcaro, Natalia \.Zywucka, Mathieu de Naurois
Published: 2023
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14. A Contribution of the HAWC Observatory to the TeV era in the High Energy Gamma-Ray Astrophysics: The case of the TeV-Halos

Author: Torres-Escobedo, Ramiro, Zhou, Hao, de la Fuente, Eduardo, Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Álvarez, J. D., Camacho, J. R. Angeles, Arteaga-Velázquez, J. C., Arunbabu, K. P., Rojas, D. Avila, Solares, H. A. Ayala, Babu, R., Baghmanyan, V., Barber, A. S., Gonzalez, J. Becerra, Belmont-Moreno, E., BenZvi, S. Y., Berley, D., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Chaparro-Amaro, O., Cotti, U., Cotzomi, J., de León, S. Coutiño, de León, C., Diaz-Cruz, L., Hernandez, R. Diaz, Díaz-Vélez, J. C., Dingus, B. L., Durocher, M., DuVernois, M. A., Ellsworth, R. W., Engel, K., Espinoza, C., Fan, K. L., Fang, K., Alonso, M. Fernández, Fick, B., Fleischhack, H., Flores, J. L., Fraija, N. I., Garcia, D., García-González, J. A., García-Torales, G., Garfias, F., Giacinti, G., Goksu, H., González, M. M., Goodman, J. A., Harding, J. P., Hernandez, S., Herzog, I., Hinton, J., Hona, B., Huang, D., Hueyotl-Zahuantitla, F., Hui, C. M., Humensky, B., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Jhee, H., Joshi, V., Kieda, D., Kunde, G J., Kunwar, S., Lara, A., Lee, J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J., Longinotti, A. L., López-Coto, R., Luis-Raya, G., Lundeen, J., Malone, K., Marandon, V., Martinez, O., Martinez-Castellanos, I., Martínez-Huerta, H., Martínez-Castro, J., Matthews, J. A. J., McEnery, J., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Olivera-Nieto, L., Omodei, N., Peisker, A., Araujo, Y. Pérez, Pérez-Pérez, E. G., Rho, C. D., Rivière, C., Rosa-Gonzalez, D., Ruiz-Velasco, E., Ryan, J., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Serna-Franco, J., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tanner, M., Tollefson, K., Torres, I., Turner, R., Ureña-Mena, F., Villaseñor, L., Wang, X., Watson, I. J., Weisgarber, T., Werner, F., Willox, E., Wood, J., Yodh, G. B., and Zepeda, A.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present a short overview of the TeV-Halos objects as a discovery and a relevant contribution of the High Altitude Water \v{C}erenkov (HAWC) observatory to TeV astrophysics. We discuss history, discovery, knowledge, and the next step through a new and more detailed analysis than the original study in 2017. TeV-Halos will contribute to resolving the problem of the local positron excess observed on the Earth. To clarify the latter, understanding the diffusion process is mandatory., Comment: Work presented in the 21st International Symposium on Very High Energy Cosmic Ray Interactions(ISVHECRI 2022) as part of the Ph. D. Thesis of Ramiro Torres-Escobedo (SJTU, Shanghai, China). Accepted for publication in SciPost Physics Proceedings (ISSN 2666-4003). 11 pages, 3 Figures. Short overview of HAWC and TeV Halos objects until 2022
Published: 2023

15. Detection of extended gamma-ray emission around the Geminga pulsar with H.E.S.S

Author: Collaboration, H. E. S. S., Aharonian, F., Benkhali, F. Ait, Aschersleben, J., Ashkar, H., Backes, M., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., Borowska, J., Bouyahiaoui, M., Bradascio, F., Brose, R., Brun, F., Bruno, B., Bulik, T., Scheidlin, C. Burger, Cangemi, F., Caroff, S., Casanova, S., Celic, J., Cerruti, M., Chambery, P., Chand, T., Chandra, S., Chen, A., Chibueze, J., Chibueze, O., Cotter, G., Mbarubucyeye, J. Damascene, Devin, J., Djannati-Ataï, A., Dmytriiev, A., Egberts, K., Einecke, S., Ernenwein, J. P., Feijen, K., de Clairfontaine, G. Fichet, Filipovic, M., Fontaine, G., Füssling, M., Funk, S., Gabici, S., Gallant, Y. A., Ghafourizadeh, S., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Goswami, P., Grolleron, G., Grondin, M. -H., Haerer, L., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Holch, T. L., Holler, M., Horns, D., Huang, Zhiqiu, Jamrozy, M., Jankowsky, F., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzyński, K., Khélifi, B., Kluźniak, W., Komin, Nu., Kosack, K., Kostunin, D., Lang, R. G., Stum, S. Le, Leitl, F., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Marinos, P., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Muller, J., Nakashima, K., de Naurois, M., Niemiec, J., Noel, A. Priyana, O'Brien, P., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Prokhorov, D. A., Pühlhofer, G., Quirrenbach, A., Reimer, A., Reimer, O., Renaud, M., Reville, B., Rieger, F., Rowell, G., Rudak, B., Ricarte, H. Rueda, Ruiz-Velasco, E., Sahakian, V., Salzmann, H., Santangelo, A., Sasaki, M., Schüssler, F., Schutte, H. M., Schwanke, U., Shapopi, J. N. S., Sinha, A., Sol, H., Specovius, A., Spencer, S., Stawarz, Ł., Steinmassl, S., Sushch, I., Suzuki, H., Takahashi, T., Tanaka, T., Tavernier, T., Taylor, A. M., Terrier, R., Thorpe-Morgan, C., Tsirou, M., Tsuji, N., Vecchi, M., Venter, C., Vink, J., Wagner, S. J., White, R., Wierzcholska, A., Wong, Yu Wun, Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zech, A., Zouari, S., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Geminga is an enigmatic radio-quiet gamma-ray pulsar located at a mere 250 pc distance from Earth. Extended very-high-energy gamma-ray emission around the pulsar was discovered by Milagro and later confirmed by HAWC, which are both water Cherenkov detector-based experiments. However, evidence for the Geminga pulsar wind nebula in gamma rays has long evaded detection by imaging atmospheric Cherenkov telescopes (IACTs) despite targeted observations. The detection of gamma-ray emission on angular scales > 2 deg poses a considerable challenge for the background estimation in IACT data analysis. With recent developments in understanding the complementary background estimation techniques of water Cherenkov and atmospheric Cherenkov instruments, the H.E.S.S. IACT array can now confirm the detection of highly extended gamma-ray emission around the Geminga pulsar with a radius of at least 3 deg in the energy range 0.5-40 TeV. We find no indications for statistically significant asymmetries or energy-dependent morphology. A flux normalisation of $(2.8\pm0.7)\times10^{-12}$ cm$^{-2}$s$^{-1}$TeV$^{-1}$ at 1 TeV is obtained within a 1 deg radius region around the pulsar. To investigate the particle transport within the halo of energetic leptons around the pulsar, we fitted an electron diffusion model to the data. The normalisation of the diffusion coefficient obtained of $D_0 = 7.6^{+1.5}_{-1.2} \times 10^{27}$ cm$^2$s$^{-1}$, at an electron energy of 100 TeV, is compatible with values previously reported for the pulsar halo around Geminga, which is considerably below the Galactic average., Comment: 16 pages, 15 figures, 7 tables. Accepted for publication in Astronomy & Astrophysics
Published: 2023
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16. The High-Altitude Water Cherenkov (HAWC) Observatory in M\'exico: The Primary Detector

Author: Abeysekara, A. U., Albert, A., Alfaro, R., Álvarez, C., Álvarez, J. D., Araya, M., Arteaga-Velázquez, J. C., Arunbabu, K. P., Rojas, D. Avila, Solares, H. A. Ayala, Babu, R., Barber, A. S., Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Blanco, O., Braun, J., Brisbois, C., Caballero-Mora, K. S., Martínez, J. I. Cabrera, Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Chaparro-Amaro, O., Cotti, U., Cotzomi, J., de León, S. Coutiño, de la Fuente, E., de León, C., De Young, T., Hernández, R. Díaz, Dingus, B. L., DuVernois, M. A., Durocher, M., Díaz-Vélez, J. C., Ellsworth, R. W., Engel, K., Espinoza, C., Fan, K. L., Fang, K., Fick, U. B., Fleischhack, H., Flores, J. L., Fraija, N., García-González, J. A., García-Torales, G., Garfias, F., Giacinti, G., Goksu, H., González, M. M., González-Muñoz, A., Goodman, J. A., Harding, J. P., Hernández, E., Hernández, S., Hinton, J., Hona, B., Huang, D., Hueyotl-Zahuantitla, F., Hui, C. M., Humensky, T. B., Hüntemeyer, P., Iriarte, A., Imran, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kieda, D., Kunde, G. J., Lara, A., Lauer, R., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Lundeen, J., Malone, K., Marandon, V., Marinelli, A., Martínez, O., Martínez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Montaruli, T., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Oceguera-Becerra, T., Olivera-Nieto, L., Omodei, N., Peisker, A., Araujo, Y. Pérez, Pérez-Pérez, E. G., Ponce, E., Pretz, J., Rho, C. D., Rosa-González, D., Ruiz-Velasco, E., Salazar, H., Salazar-Gallegos, D., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Serna-Franco, J., Sinnis, G., Smith, A. J., Son, Y., Woodle, K. Sparks, Springer, R. W., Taboada, I., Tepe, A., Tibolla, O., Tollefson, K., Torres, I., Torres-Escobedo, R., Turner, R., Ureña-Mena, F., Ukwatta, T. N., Varela, E., Vargas-Magaña, M., Villaseñor, L., Wang, X., Watson, I. J., Werner, F., Westerhoff, S., Willox, E., Wisher, I., Wood, J., Yodh, G. B., Zaborov, D., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: The High-Altitude Water Cherenkov (HAWC) observatory is a second-generation continuously operated, wide field-of-view, TeV gamma-ray observatory. The HAWC observatory and its analysis techniques build on experience of the Milagro experiment in using ground-based water Cherenkov detectors for gamma-ray astronomy. HAWC is located on the Sierra Negra volcano in M\'exico at an elevation of 4100 meters above sea level. The completed HAWC observatory principal detector (HAWC) consists of 300 closely spaced water Cherenkov detectors, each equipped with four photomultiplier tubes to provide timing and charge information to reconstruct the extensive air shower energy and arrival direction. The HAWC observatory has been optimized to observe transient and steady emission from sources of gamma rays within an energy range from several hundred GeV to several hundred TeV. However, most of the air showers detected are initiated by cosmic rays, allowing studies of cosmic rays also to be performed. This paper describes the characteristics of the HAWC main array and its hardware., Comment: Accepted for publications in Nuclear Inst. and Methods in Physics Research, A (2023) 168253 ( https://www.sciencedirect.com/science/article/abs/pii/S0168900223002437 ); 39 pages, 14 Figures
Published: 2023
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17. Sensitivity of the Cherenkov Telescope Array to spectral signatures of hadronic PeVatrons with application to Galactic Supernova Remnants

Author: Consortium, The Cherenkov Telescope Array, Acero, F., Acharyya, A., Adam, R., Aguasca-Cabot, A., Agudo, I., Aguirre-Santaella, A., Alfaro, J., Aloisio, R., Crespo, N. Álvarez, Batista, R. Alves, Amati, L., Amato, E., Ambrosi, G., Angüner, E. O., Aramo, C., Arcaro, C., Armstrong, T., Asano, K., Ascasibar, Y., Aschersleben, J., Backes, M., Baktash, A., Balazs, C., Balbo, M., Ballet, J., Larriva, A. Baquero, Martins, V. Barbosa, de Almeida, U. Barres, Barrio, J. A., Bastieri, D., Baxter, J. R., Tjus, J. Becker, Benbow, W., Bernardos-Martín, M. I., Bernete, J., Berti, A., Bertucci, B., Beshley, V., Bhattacharjee, P., Bhattacharyya, S., Biland, A., Bissaldi, E., Biteau, J., Blanch, O., Bordas, P., Bottacini, E., Bregeon, J., Brose, R., Bucciantini, N., Bulgarelli, A., Capasso, M., Dolcetta, R. A. Capuzzo, Caraveo, P., Cardillo, M., Carosi, R., Casanova, S., Cascone, E., Cassol, F., Catalani, F., Cerruti, M., Chadwick, P., Chaty, S., Chen, A., Chernyakova, M., Chiavassa, A., Chudoba, J., Coimbra-Araujo, C., Conforti, V., Contreras, J. L., Costa, A., Costantini, H., Cristofari, P., Crocker, R., D'Amico, G., D'Ammando, F., De Angelis, A., De Caprio, V., Pino, E. M. de Gouveia Dal, Wilhelmi, E. de Ona, de Souza, V., Delgado, C., della Volpe, D., Depaoli, D., Di Girolamo, T., Di Pierro, F., Di Tria, R., Di Venere, L., Diebold, S., Djuvsland, J. I., Donini, A., Doro, M., Anjos, R. d. C. Dos, Dwarkadas, V. V., Einecke, S., Elsässer, D., Emery, G., Evoli, C., Falceta-Goncalves, D., Fedorova, E., Fegan, S., Ferrand, G., Fiandrini, E., Filipovic, M., Fioretti, V., Fiori, M., Foffano, L., Fontaine, G., Fukami, S., Galanti, G., Galaz, G., Gammaldi, V., Gasbarra, C., Ghalumyan, A., Ghirlanda, G., Giarrusso, M., Giavitto, G., Giglietto, N., Giordano, F., Giroletti, M., Giuliani, A., Giunti, L., Godinovic, N., Coelho, J. Goulart, Gréaux, L., Green, D., Grondin, M-H., Gueta, O., Gunji, S., Hassan, T., Heller, M., Hernández-Cadena, S., Hinton, J., Hnatyk, B., Hnatyk, R., Hoffmann, D., Hofmann, W., Holder, J., Horan, D., Horvath, P., Hrabovsky, M., Hrupec, D., Inada, T., Incardona, F., Inoue, S., Ishio, K., Jamrozy, M., Janecek, P., Martínez, I. Jiménez, Jin, W., Jung-Richardt, I., Jurysek, J., Kaaret, P., Karas, V., Katz, U., Kerszberg, D., Khélifi, B., Kieda, D. B., Kissmann, R., Kleiner, T., Kluge, G., Kluzniak, W., Knödlseder, J., Kobayashi, Y., Kohri, K., Komin, N., Kornecki, P., Kubo, H., La Palombara, N., Láinez, M., Lamastra, A., Lapington, J., Lemoine-Goumard, M., Lenain, J. -P., Leone, F., Leto, G., Leuschner, F., Lindfors, E., Liodakis, I., Lohse, T., Lombardi, S., Longo, F., López-Coto, R., López-Moya, M., López-Oramas, A., Loporchio, S., Luque-Escamilla, P. L., Macias, O., Mackey, J., Majumdar, P., Mandat, D., Manganaro, M., Manicò, G., Marconi, M., Martí, J., Martínez, G., Martinez, M., Martinez, O., Mello, A. J. T. S., Menchiari, S., Meyer, D. M. -A., Micanovic, S., Miceli, D., Miceli, M., Michalowski, J., Miener, T., Miranda, J. M., Mitchell, A., Mode, B., Moderski, R., Mohrmann, L., Molina, E., Montaruli, T., Morcuende, D., Morlino, G., Morselli, A., Mosè, M., Moulin, E., Mukherjee, R., Munari, K., Murach, T., Nagai, A., Nagataki, S., Nemmen, R., Niemiec, J., Nieto, D., Rosillo, M. Nievas, Nikolajuk, M., Nishijima, K., Noda, K., Novosyadlyj, B., Nozaki, S., Ohishi, M., Ohm, S., Ohtani, Y., Okumura, A., Olmi, B., Ong, R. A., Orienti, M., Orito, R., Orlandini, M., Orlando, E., Orlando, S., Ostrowski, M., Oya, I., Pantaleo, F. R., Paredes, J. M., Patricelli, B., Pecimotika, M., Peresano, M., Pérez-Romero, J., Persic, M., Petruk, O., Piano, G., Pietropaolo, E., Pirola, G., Pittori, C., Pohl, M., Ponti, G., Prandini, E., Principe, G., Priyadarshi, C., Pueschel, E., Pühlhofer, G., Pumo, M. L., Quirrenbach, A., Rando, R., Razzaque, S., Reichherzer, P., Reimer, A., Reimer, O., Renaud, M., Reposeur, T., Ribó, M., Richtler, T., Rico, J., Rieger, F., Rigoselli, M., Riitano, L., Rizi, V., Roache, E., Romano, P., Romeo, G., Rosado, J., Rowell, G., Rudak, B., Sadeh, I., Safi-Harb, S., Saha, L., Sailer, S., Sánchez-Conde, M., Sarkar, S., Satalecka, K., Saturni, F. G., Scherer, A., Schovánek, P., Schussler, F., Schwanke, U., Scuderi, S., Seglar-Arroyo, M., Sergijenko, O., Servillat, M., Shang, R-Y., Sharma, P., Siejkowski, H., Sliusar, V., Słowikowska, A., Sol, H., Specovius, A., Spencer, S. T., Spengler, G., Stamerra, A., Stanič, S., Starecki, T., Starling, R., Stolarczyk, T., Pereira, L. A. Stuani, Suda, Y., Suomijarvi, T., Sushch, I., Tajima, H., Tam, P-H. T., Tanaka, S. J., Tavecchio, F., Testa, V., Tian, W., Tibaldo, L., Torres, D. F., Tothill, N., Vallage, B., Vallania, P., van Eldik, C., van Scherpenberg, J., Vandenbroucke, J., Acosta, M. Vazquez, Vecchi, M., Vercellone, S., Verna, G., Viana, A., Vignatti, J., Vitale, V., Vodeb, V., Vorobiov, S., Vuillaume, T., Wagner, S. J., Walter, R., White, M., Wierzcholska, A., Will, M., Williams, D., Yang, L., Yoshida, T., Yoshikoshi, T., Zaharijas, G., Zampieri, L., Zavrtanik, D., Zavrtanik, M., Zhdanov, V. I., and Živec, M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: The local Cosmic Ray (CR) energy spectrum exhibits a spectral softening at energies around 3~PeV. Sources which are capable of accelerating hadrons to such energies are called hadronic PeVatrons. However, hadronic PeVatrons have not yet been firmly identified within the Galaxy. Several source classes, including Galactic Supernova Remnants (SNRs), have been proposed as PeVatron candidates. The potential to search for hadronic PeVatrons with the Cherenkov Telescope Array (CTA) is assessed. The focus is on the usage of very high energy $\gamma$-ray spectral signatures for the identification of PeVatrons. Assuming that SNRs can accelerate CRs up to knee energies, the number of Galactic SNRs which can be identified as PeVatrons with CTA is estimated within a model for the evolution of SNRs. Additionally, the potential of a follow-up observation strategy under moonlight conditions for PeVatron searches is investigated. Statistical methods for the identification of PeVatrons are introduced, and realistic Monte--Carlo simulations of the response of the CTA observatory to the emission spectra from hadronic PeVatrons are performed. Based on simulations of a simplified model for the evolution for SNRs, the detection of a $\gamma$-ray signal from in average 9 Galactic PeVatron SNRs is expected to result from the scan of the Galactic plane with CTA after 10 hours of exposure. CTA is also shown to have excellent potential to confirm these sources as PeVatrons in deep observations with $\mathcal{O}(100)$ hours of exposure per source., Comment: 34 pages, 16 figures, Accepted for publication in Astroparticle Physics
Published: 2023
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18. Search for the evaporation of primordial black holes with H.E.S.S

Author: collaboration, H. E. S. S., Aharonian, F., Benkhali, F. Ait, Aschersleben, J., Boettcher, M., Backes, M., Martins, V. Barbosa, Batzo, R., Becherini, Y., Berge, D., Bi, B., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Borowska, J., Bradascio, F., Brose, R., Brun, F., Bruno, B., Bulik, T., Burger-Scheidlin, C., Caro, S., Casanova, S., Celic, J., Cerruti, M., Chand, T., Chen, A., Chibueze, O., Cotter, G., Mbarubucyeye, J. Damascene, Djannati-Atai, A., Egberts, K., van Eldik, C., Ernenwein, J. -P., Fussling, M., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Gabici, S., Ghafourizadeh, S., Giavitto, G., Glawion, D., Glicenstein, J. F., Grolleron, G., Grondin, M. -H., Haerer, L., Haupt, M., Hinton, J. A., Hofmann, W., Holler, M., Horns, D., Huang, Zhiqiu, Jamrozy, M., Jankowsky, F., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzynski, K., Khelifi, B., Klepser, S., Kluzniak, W., Komin, Nu., Kosack, K., Kostunin, D., Holch, T. L., Lang, R. G., Stum, S. Le, Leitl, F., Lemiere, A., Lenain, J. -P., Leuschner, F., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Malyshev, D., Marandon, V., Marchegiani, P., Marinos, P., Marti-Devesa, G., Marx, R., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Muller, J., Nakashima, K., de Naurois, M., Niemiec, J., O'Brien, P., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Puehlhofer, G., Panny, S., Panter, M., Parsons, R. D., Peron, G., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Punch, M., Quirrenbach, A., Reichherzer, P., Reimer, O., Rieger, F., Rowell, G., Rudak, B., Ricarte, H. Rueda, Sahakian, V., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Schutte, H. M., Schwanke, U., Shapopi, J. N. S., Sol, H., Specovius, A., Spencer, S., Stawarz, L., Steenkamp, R., Steinmassl, S., Steppa, C., Sushch, I., Suzuki, H., Takahashi, T., Tanaka, T., Tavernier, T., Thorpe-Morgan, C., Tsuji, N., Uchiyama, Y., Vecchi, M., Veh, J., Venter, C., Vink, J., Wagner, S. J., White, R., Wierzcholska, A., Wong, Yu Wun, Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zech, A., Zouari, S., and Zywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Primordial Black Holes (PBHs) are hypothetical black holes predicted to have been formed from density fluctuations in the early Universe. PBHs with an initial mass around $10^{14}-10^{15}$g are expected to end their evaporation at present times in a burst of particles and very-high-energy (VHE) gamma rays. Those gamma rays may be detectable by the High Energy Stereoscopic System (H.E.S.S.), an array of imaging atmospheric Cherenkov telescopes. This paper reports on the search for evaporation bursts of VHE gamma rays with H.E.S.S., ranging from 10 to 120 seconds, as expected from the final stage of PBH evaporation and using a total of 4816 hours of observations. The most constraining upper limit on the burst rate of local PBHs is $2000$ pc$^{-3}$ yr$^{-1}$ for a burst interval of 120 seconds, at the 95\% confidence level. The implication of these measurements for PBH dark matter are also discussed., Comment: Accepted for publication in JCAP, corresponding authors: F.Brun, J-F. Glicenstein, V. Marandon, T. Tavernier
Published: 2023
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19. Detailed Analysis of the TeV {\gamma}-Ray Sources 3HWC J1928+178, 3HWC J1930+188, and the New Source HAWC J1932+192

Author: Albert, A., Alfaro, R., Alvarez, C., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Babu, R., Belmont-Moreno, E., Brisbois, C., Caballero-Mora, K. S., Capistrń, T., Carramiñana, A., Casanova, S., Chaparro-Amaro, O., Cotti, U., Cotzomi, J., CoutiñodeLeón, S., De la Fuente, E., de León, C., Hernandez, R. Diaz, Díaz-Vélez, J. C., Dingus, B. L., DuVernois, M. A., Durocher, M., Engel, K., Espinoza, C., Fan, K. L., Alonso, M. Fernández, Fraija, N., García-González, J. A., Garfias, F., Goksu, H., González, M. M., Goodman, J. A., Harding, J. P., Hernandez, S., Hinton, J., Hona, B., Huang, D., Hueyotl-Zahuantitla, F., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kieda, D., Lee, W. H., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., López-Coto, R., Malone, K., Marandon, V., Martinez, O., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Olivera-Nieto, L., Omodei, N., Peisker, A., Araujo, Y. Pérez, Pérez-Pérez, E. G., Rho, C. D., Rosa-González, D., Ruiz-Velasco, E., Salazar, H., Salazar-Gallegos, D., Greus, F. Salesa, Sandoval, A., Schneider, M., Serna-Franco, J., Smith, A. J., Son, Y., Springer, R. W., Tibolla, O., Tollefson, K., Torres, I., Torres-Escobedo, R., Turner, R., Ureña-Mena, F., Villaseñor, L., Wang, X., Werner, F., Willox, E., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The latest High Altitude Water Cherenkov (HAWC) point-like source catalog up to 56 TeV reported the detection of two sources in the region of the Galactic plane at galactic longitude 52\deg < l < 55\deg, 3HWC J1930+188 and 3HWC J1928+178. The first one is associated with a known TeV source, the supernova remnant SNR G054.1+00.3. It was discovered by one of the currently operating Imaging Atmospheric Cherenkov Telescope (IACT), the Very Energetic Radiation Imaging Telescope Array System (VERITAS), detected by the High Energy Stereoscopic System (H.E.S.S.), and identified as a composite SNR. However, the source 3HWC J1928+178, discovered by HAWC and coincident with the pulsar PSR J1928+1746, was not detected by any IACT despite their long exposure on the region, until a recent new analysis of H.E.S.S. data was able to confirm it. Moreover, no X-ray counterpart has been detected from this pulsar. We present a multicomponent fit of this region using the latest HAWC data. This reveals an additional new source, HAWC J1932+192, which is potentially associated with the pulsar PSR J1932+1916, whose gamma-ray emission could come from the acceleration of particles in its pulsar wind nebula. In the case of 3HWC J1928+178, several possible explanations are explored, in a attempt to unveil the origins of the very-high-energy gamma-ray emission.
Published: 2023
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20. HESS J1809$-$193: a halo of escaped electrons around a pulsar wind nebula?

Author: Collaboration, H. E. S. S., Aharonian, F., Benkhali, F. Ait, Aschersleben, J., Ashkar, H., Backes, M., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Böttcher, M., Boisson, C., Bolmont, J., Borowska, J., Bouyahiaoui, M., Bradascio, F., Breuhaus, M., Brose, R., Brun, F., Bruno, B., Bulik, T., Burger-Scheidlin, C., Bylund, T., Caroff, S., Casanova, S., Celic, J., Cerruti, M., Chambery, P., Chand, T., Chen, A., Chibueze, J., Chibueze, O., Mbarubucyeye, J. Damascene, Djannati-Ataï, A., Dmytriiev, A., Einecke, S., Ernenwein, J. -P., Feijen, K., Filipovic, M., Fontaine, G., Füßling, M., Funk, S., Gabici, S., Gallant, Y. A., Ghafourizadeh, S., Giavitto, G., Giunti, L., Glawion, D., Goswami, P., Grolleron, G., Grondin, M. -H., Haerer, L., Hinton, J. A., Hofmann, W., Holch, T. L., Holler, M., Horns, D., Huang, Zhiqiu, Jamrozy, M., Jankowsky, F., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzyński, K., Khélifi, B., Kluźniak, W., Komin, Nu., Kosack, K., Kostunin, D., Lang, R. G., Stum, S. Le, Leitl, F., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Marinos, P., Martí-Devesa, G., Marx, R., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Muller, J., Nakashima, K., de Naurois, M., Niemiec, J., Noel, A. Priyana, Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Prokhorov, D. A., Pühlhofer, G., Punch, M., Quirrenbach, A., Reichherzer, P., Reimer, A., Reimer, O., Renaud, M., Reville, B., Rieger, F., Rowell, G., Rudak, B., Sahakian, V., Santangelo, A., Sasaki, M., Schutte, H. M., Schwanke, U., Shapopi, J. N. S., Sol, H., Specovius, A., Spencer, S., Stawarz, Ł., Steenkamp, R., Steinmassl, S., Sushch, I., Suzuki, H., Takahashi, T., Tanaka, T., Terrier, R., Thorpe-Morgan, C., Tsirou, M., Tsuji, N., Uchiyama, Y., van Eldik, C., Vecchi, M., Veh, J., Venter, C., Vink, J., Wach, T., Wagner, S. J., White, R., Wierzcholska, A., Wong, Yu Wun, Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zech, A., Zouari, S., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Context. HESS J1809$-$193 is an unassociated very-high-energy $\gamma$-ray source located on the Galactic plane. While it has been connected to the nebula of the energetic pulsar PSR J1809$-$1917, supernova remnants and molecular clouds present in the vicinity also constitute possible associations. Recently, the detection of $\gamma$-ray emission up to energies of $\sim$100 TeV with the HAWC observatory has led to renewed interest in HESS J1809$-$193. Aims. We aim to understand the origin of the $\gamma$-ray emission of HESS J1809$-$193. Methods. We analysed 93.2 h of data taken on HESS J1809$-$193 above 0.27 TeV with the High Energy Stereoscopic System (H.E.S.S.), using a multi-component, three-dimensional likelihood analysis. In addition, we provide a new analysis of 12.5 yr of Fermi-LAT data above 1 GeV within the region of HESS J1809$-$193. The obtained results are interpreted in a time-dependent modelling framework. Results. For the first time, we were able to resolve the emission detected with H.E.S.S. into two components: an extended component that exhibits a spectral cut-off at $\sim$13 TeV, and a compact component that is located close to PSR J1809$-$1917 and shows no clear spectral cut-off. The Fermi-LAT analysis also revealed extended $\gamma$-ray emission, on scales similar to that of the extended H.E.S.S. component. Conclusions. Our modelling indicates that based on its spectrum and spatial extent, the extended H.E.S.S. component is likely caused by inverse Compton emission from old electrons that form a halo around the pulsar wind nebula. The compact component could be connected to either the pulsar wind nebula or the supernova remnant and molecular clouds. Due to its comparatively steep spectrum, modelling the Fermi-LAT emission together with the H.E.S.S. components is not straightforward. (abridged), Comment: 14 pages, 10 figures. Accepted for publication in A&A. Corresponding authors: Vikas Joshi, Lars Mohrmann
Published: 2023
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21. The TeV Sun Rises: Discovery of Gamma rays from the Quiescent Sun with HAWC

Author: Albert, A., Alfaro, R., Alvarez, C., Arteaga-Velazquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Babu, R., Belmont-Moreno, E., Brisbois, C., Caballero-Mora, K. S., Capistran, T., Carraminana, A., Casanova, S., Chaparro-Amaro, O., Cotti, U., Cotzomi, J., de Leon, S. Coutino, De la Fuente, E., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Durocher, M., Diaz-Velez, J. C., Ellsworth, R. W., Engel, K., Espinoza, C., Fan, K. L., Fang, K., Alonso, M. Fernandez, Fleischhack, H., Fraija, N., Garcia-Gonzalez, J. A., Garfia, F., Gonzalez, M. M., Goodman, J. A., Harding, J. P., Hernandez, S., Hinton, J., Huang, D., Hueyotl-Zahuantitla, F., Huntemeyer, P., Iriarte, A., Joshi, V., Kaufmann, S., Lee, J., Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Malone, K., Martinez, O., Martinez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafa, M., Nayerhoda, A., Nellen, L., Nisa, M. U., Noriega-Papaqui, R., Olivera-Nieto, L., Omodei, N., Araujo, Y. Pérez, Perez-Perez, E. G., Rho, C. D., Rosa-Gonzalez, D., Ruiz-Velasco, E., Salazar, H., Salazar-Gallegos, D., Sandoval, A., Schneider, M., Serna-Franco, J., Smith, A. J., Son, Y., Springer, R. W., Tibolla, O., Tollefson, K., Torres, I., Torres-Escobedo, R., Turner, R., Urena-Mena, F., Wang, X., Watson, I. J., Willox, E., Yun-Cárcamo, S., Zhou, H., de León, C., Beacom, J. F., Linden, T., Ng, K. C. Y., Peter, A. H. G., and Zhou, B.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics, High Energy Physics - Experiment
Abstract: We report the first detection of a TeV gamma-ray flux from the solar disk (6.3$\sigma$), based on 6.1 years of data from the High Altitude Water Cherenkov (HAWC) observatory. The 0.5--2.6 TeV spectrum is well fit by a power law, dN/dE = $A (E/1 \text{ TeV})^{-\gamma}$, with $A = (1.6 \pm 0.3) \times 10^{-12}$ TeV$^{-1}$ cm$^{-2}$ s$^{-1}$ and $\gamma = -3.62 \pm 0.14$. The flux shows a strong indication of anticorrelation with solar activity. These results extend the bright, hard GeV emission from the disk observed with Fermi-LAT, seemingly due to hadronic Galactic cosmic rays showering on nuclei in the solar atmosphere. However, current theoretical models are unable to explain the details of how solar magnetic fields shape these interactions. HAWC's TeV detection thus deepens the mysteries of the solar-disk emission., Comment: 15 pages, 8 figures including supplementary material. Accepted for publication in Physical Review Letters
Published: 2022
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22. Gamma-ray observations of MAXI J1820+070 during the 2018 outburst

Author: Abe, H., Abe, S., Acciari, V. A., Aniello, T., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Arcaro, C., Artero, M., Asano, K., Baack, D., Babić, A., Baquero, A., de Almeida, U. Barres, Barrio, J. A., Batković, I., Baxter, J., González, J. Becerra, Bednarek, W., Bernardini, E., Bernardos, M., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Bošnjak, Ž., Burelli, I., Busetto, G., Carosi, R., Carretero-Castrillo, M., Ceribella, G., Chai, Y., Chilingarian, A., Cikota, S., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Del Popolo, A., Delfino, M., Delgado, J., Mendez, C. Delgado, Depaoli, D., Di Pierro, F., Di Venere, L., Prester, D. Dominis, Donini, A., Dorner, D., Doro, M., Elsaesser, D., Emery, G., Ramazani, V. Fallah, Fariña, L., Fattorini, A., Font, L., Fruck, C., Fukami, S., Fukazawa, Y., López, R. J. García, Garczarczyk, M., Gasparyan, S., Gaug, M., Paiva, J. G. Giesbrecht, Giglietto, N., Giordano, F., Gliwny, P., Godinović, N., Grau, R., Green, D., Green, J. G., Hadasch, D., Hahn, A., Hassan, T., Heckmann, L., Herrera, J., Hoang, J., Hrupec, D., Hütten, M., Imazawa, R., Inada, T., Iotov, R., Ishio, K., Martínez, I. Jiménez, Jormanainen, J., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Linhoff, L., Lombardi, S., Longo, F., López-Coto, R., López-Moya, M., López-Oramas, A., Loporchio, S., Lorini, A., Lyard, E., Fraga, B. Machado de Oliveira, Majumdar, P., Makariev, M., Maneva, G., Mang, N., Manganaro, M., Mangano, S., Mannheim, K., Mariotti, M., Martínez, M., Aguilar, A. Mas, Mazin, D., Menchiari, S., Mender, S., Mićanović, S., Miceli, D., Miener, T., Miranda, J. M., Mirzoyan, R., Molina, E., Mondal, H. A., Moralejo, A., Morcuende, D., Moreno, V., Nakamori, T., Nanci, C., Nava, L., Neustroev, V., Rosillo, M. Nievas, Nigro, C., Nilsson, K., Nishijima, K., Ekoume, T. Njoh, Noda, K., Nozaki, S., Ohtani, Y., Oka, T., Okumura, A., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavletić, L., Persic, M., Pihet, M., Pirola, G., Podobnik, F., Moroni, P. G. Prada, Prandini, E., Principe, G., Priyadarshi, C., Puljak, I., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Saturni, F. G., Schleicher, B., Schmidt, K., Schmuckermaier, F., Schubert, J. L., Schweizer, T., Sitarek, J., Sliusar, V., Sobczynska, D., Spolon, A., Stamerra, A., Strišković, J., Strom, D., Strzys, M., Suda, Y., Surić, T., Tajima, H., Takahashi, M., Takeishi, R., Tavecchio, F., Temnikov, P., Terauchi, K., Terzić, T., Teshima, M., Tosti, L., Truzzi, S., Tutone, A., Ubach, S., van Scherpenberg, J., Acosta, M. Vazquez, Ventura, S., Verguilov, V., Viale, I., Vigorito, C. F., Vitale, V., Vovk, I., Walter, R., Will, M., Wunderlich, C., Yamamoto, T., Zarić, D., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernlöhr, K., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Bradascio, F., Breuhaus, M., Brose, R., Brun, F., Bulik, T., Bylund, T., Cangemi, F., Caroff, S., Casanova, S., Cerruti, M., Chand, T., Chandra, S., Chen, A., Chibueze, O. U., Cotter, G., Cristofari, P., Mbarubucyeye, J. Damascene, Devin, J., Djannati-Ataï, A., Dmytriiev, A., Egberts, K., Ernenwein, J. -P., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Füßling, M., Funk, S., Gabici, S., Ghafourizadeh, S., Giavitto, G., Glawion, D., Glicenstein, J. F., Goswami, P., Grolleron, G., Hinton, J. A., Hörbe, M., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huang, Zhiqiu, Jamrozy, M., Jankowsky, F., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzyński, K., Katz, U., Khélifi, B., Kluźniak, W., Komin, Nu., Kosack, K., Kostunin, D., Lang, R. G., Stum, S. Le, Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Martí-Devesa, G., Marx, R., Maurin, G., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Muller, J., Murach, T., Nakashima, K., de Naurois, M., Nayerhoda, A., Niemiec, J., Noel, A. Priyana, O'Brien, P., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Poireau, V., Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Reichherzer, P., Reimer, A., Reimer, O., Renaud, M., Rieger, F., Rowell, G., Rudak, B., Ricarte, H. Rueda, Ruiz-Velasco, E., Sahakian, V., Salzmann, H., Santangelo, A., Sasaki, M., Schäfer, J., Schüssler, F., Schutte, H. M., Schwanke, U., Shapopi, J. N. S., Sol, H., Specovius, A., Spencer, S., Stawarz, Ł., Steenkamp, R., Steinmassl, S., Steppa, C., Sushch, I., Suzuki, H., Takahashi, T., Tanaka, T., Thorpe-Morgan, C., Tluczykont, M., Tomankova, L., Tsuji, N., Uchiyama, Y., van Eldik, C., van Soelen, B., Vecchi, M., Veh, J., Venter, C., Vink, J., Wagner, S. J., White, R., Wierzcholska, A., Wong, Yu Wun, Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zouari, S., Żywucka, N., Acharyya, A., Adams, C. B., Batista, P., Benbow, W., Capasso, M., Christiansen, J. L., Chromey, A. J., Errando, M., Falcone, A., Feng, Q., Finley, J. P., Foote, G. M, Fortson, L., Furniss, A., Gent, A., Hanlon, W. F, Hervet, O., Holder, J., Hona, B., Humensky, T. B., Jin, W., Kaaret, P., Kertzman, M., Kherlakian, M., Kleiner, T. K., Kumar, S., Lang, M. J., Lundy, M., Maier, G., McGrath, C. E., Millis, J., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Park, N., Patel, S. R., Pfrang, K., Pohl, M., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Ribeiro, D., Roache, E., Ryan, J. L., Sadeh, I., Saha, L., Santander, M., Sembroski, G. H., Shang, R., Splettstoesser, M., Tak, D., Tucci, J. V., Weinstein, A., Williams, D. A., Williamson, T. J., Bosch-Ramon, V., Celma, C., Linares, M., Russell, D. M., and Sala, G.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: MAXI J1820+070 is a low-mass X-ray binary with a black hole as a compact object. This binary underwent an exceptionally bright X-ray outburst from March to October 2018, showing evidence of a non-thermal particle population through its radio emission during this whole period. The combined results of 59.5 hours of observations of the MAXI J1820+070 outburst with the H.E.S.S., MAGIC and VERITAS experiments at energies above 200 GeV are presented, together with Fermi-LAT data between 0.1 and 500 GeV, and multiwavelength observations from radio to X-rays. Gamma-ray emission is not detected from MAXI J1820+070, but the obtained upper limits and the multiwavelength data allow us to put meaningful constraints on the source properties under reasonable assumptions regarding the non-thermal particle population and the jet synchrotron spectrum. In particular, it is possible to show that, if a high-energy gamma-ray emitting region is present during the hard state of the source, its predicted flux should be at most a factor of 20 below the obtained Fermi-LAT upper limits, and closer to them for magnetic fields significantly below equipartition. During the state transitions, under the plausible assumption that electrons are accelerated up to ~ 500 GeV, the multiwavelength data and the gamma-ray upper limits lead consistently to the conclusion that a potential high-energy and very-high-energy gamma-ray emitting region should be located at a distance from the black hole ranging between 10^11 and 10^13 cm. Similar outbursts from low-mass X-ray binaries might be detectable in the near future with upcoming instruments such as CTA., Comment: 15 pages, 5 figures. Accepted for publication in MNRAS
Published: 2022
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23. Limits on the Diffuse Gamma-Ray Background above 10 TeV with HAWC

Author: HAWC Collaboration, Albert, A., Alfaro, R., Alvarez, C., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Babu, R., Belmont-Moreno, E., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Chaparro-Amaro, O., Cotti, U., Cotzomi, J., de León, S. Coutiño, De la Fuente, E., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Durocher, M., Díaz-Vélez, J. C., Engel, K., Espinoza, C., Fan, K. L., Alonso, M. Fernández, Fraija, N., Garcia, D., García-González, J. A., Garfias, F., González, M. M., Goodman, J. A., Harding, J. P., Hernandez, S., Hinton, J., Huang, D., Hueyotl-Zahuantitla, F., Hüntemeyer, P., Iriarte, A., Joshi, V., Kaufmann, S., Kieda, D., Lara, A., Lee, W. H., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Malone, K., Martinez, O., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Omodei, N., Peisker, A., Araujo, Y. Pérez, Pérez-Pérez, E. G., Rho, C. D., Rosa-González, D., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Serna-Franco, J., Smith, A. J., Son, Y., Springer, R. W., Tibolla, O., Tollefson, K., Torres, I., Torres-Escobedo, R., Turner, R., Ureña-Mena, F., Villaseñor, L., Wang, X., Willox, E., Zhou, H., de León, C., and Álvarez, J. D.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The high-energy Diffuse Gamma-Ray Background (DGRB) is expected to be produced by unresolved isotropically distributed astrophysical objects, potentially including dark matter annihilation or decay emissions in galactic or extragalactic structures. The DGRB has only been observed below 1 TeV; above this energy, upper limits have been reported. Observations or stringent limits on the DGRB above this energy could have significant multi-messenger implications, such as constraining the origin of TeV-PeV astrophysical neutrinos detected by IceCube. The High Altitude Water Cherenkov (HAWC) Observatory, located in central Mexico at 4100 m above sea level, is sensitive to gamma rays from a few hundred GeV to several hundred TeV and continuously observes a wide field-of-view (2 sr). With its high-energy reach and large area coverage, HAWC is well-suited to notably improve searches for the DGRB at TeV energies. In this work, strict cuts have been applied to the HAWC dataset to better isolate gamma-ray air showers from background hadronic showers. The sensitivity to the DGRB was then verified using 535 days of Crab data and Monte Carlo simulations, leading to new limits above 10 TeV on the DGRB as well as prospective implications for multi-messenger studies., Comment: 8 pages, 3 figures
Published: 2022

24. A deep spectromorphological study of the $\gamma$-ray emission surrounding the young massive stellar cluster Westerlund 1

Author: Aharonian, F., Ashkar, H., Backes, M., Martins, V. Barbosa, Becherini, Y., Berge, D., Bi, B., Böttcher, M., de Lavergne, M. de Bony, Bradascio, F., Brose, R., Brun, F., Bulik, T., Burger-Scheidlin, C., Cangemi, F., Caroff, S., Casanova, S., Cerruti, M., Chand, T., Chandra, S., Chen, A., Chibueze, O., Cristofari, P., Mbarubucyeye, J. Damascene, Djannati-Ataï, A., Ernenwein, J. -P., Feijen, K., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Gabici, S., Gallant, Y. A., Ghafourizadeh, S., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Goswami, P., Grondin, M. -H., Härer, L. K., Haupt, M., Hinton, J. A., Hörbe, M., Hofmann, W., Holch, T. L., Holler, M., Horns, D., Jamrozy, M., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzyński, K., Katz, U., Khélifi, B., Kluźniak, W., Komin, Nu., Kosack, K., Kostunin, D., Mezek, G. Kukec, Lang, R. G., Stum, S. Le, Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Martí-Devesa, G., Marx, R., Maurin, G., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Muller, J., Murach, T., Nakashima, K., de Naurois, M., Nayerhoda, A., Niemiec, J., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Prokhorov, D. A., Pühlhofer, G., Punch, M., Quirrenbach, A., Rauth, R., Reichherzer, P., Reimer, A., Reimer, O., Renaud, M., Reville, B., Rieger, F., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Schüssler, F., Schutte, H. M., Schwanke, U., Shapopi, J. N. S., Specovius, A., Spencer, S., Stawarz, Ł., Steenkamp, R., Steinmassl, S., Steppa, C., Sushch, I., Suzuki, H., Takahashi, T., Tanaka, T., Terrier, R., Thorpe-Morgan, C., Tsirou, M., Tsuji, N., Tuffs, R., Unbehaun, T., van Eldik, C., van Soelen, B., Vecchi, M., Veh, J., Venter, C., Vink, J., Wagner, S. J., White, R., Wierzcholska, A., Wong, Yu Wun, Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zhu, S. J., Zouari, S., Żywucka, N., Blackwell, R., Braiding, C., Burton, M., Cubuk, K., Filipović, M., Tothill, N., and Wong, G.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Young massive stellar clusters are extreme environments and potentially provide the means for efficient particle acceleration. Indeed, they are increasingly considered as being responsible for a significant fraction of cosmic rays (CRs) accelerated within the Milky Way. Westerlund 1, the most massive known young stellar cluster in our Galaxy is a prime candidate for studying this hypothesis. While the very-high-energy $\gamma$-ray source HESS J1646-458 has been detected in the vicinity of Westerlund 1 in the past, its association could not be firmly identified. We aim to identify the physical processes responsible for the $\gamma$-ray emission around Westerlund 1 and thus to better understand the role of massive stellar clusters in the acceleration of Galactic CRs. Using 164 hours of data recorded with the High Energy Stereoscopic System (H.E.S.S.), we carried out a deep spectromorphological study of the $\gamma$-ray emission of HESS J1646-458. We furthermore employed H I and CO observations of the region to infer the presence of gas that could serve as target material for interactions of accelerated CRs. We detected large-scale ($\sim 2^\circ$ diameter) $\gamma$-ray emission with a complex morphology, exhibiting a shell-like structure and showing no significant variation with $\gamma$-ray energy. The combined energy spectrum of the emission extends to several tens of TeV, and is uniform across the entire source region. We did not find a clear correlation of the $\gamma$-ray emission with gas clouds as identified through H I and CO observations. We conclude that, of the known objects within the region, only Westerlund 1 can explain the bulk of the $\gamma$-ray emission. Several CR acceleration sites and mechanisms are conceivable, and discussed in detail. (abridged), Comment: 15 pages, 9 figures. Corresponding authors: L. Mohrmann, S. Ohm, R. Rauth, A. Specovius. v2: corrected affiliation of M. Vecchi (still incorrect in journal version)
Published: 2022
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25. Search for dark matter annihilation signals in the H.E.S.S. Inner Galaxy Survey

Author: Collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Anguner, E. O., Armand, C., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernlohr, K., Bi, B., Bottcher, M., Bolmont, J., de Lavergne, M. de Bony, Brose, R., Brun, F., Cangemi, F., Caroff, S., Cerruti, M., Chand, T., Chen, A., Cotter, G., Mbarubucyeye, J. Damascene, Devin, J., Djannati-Ataı, A., Dmytriiev, A., Doroshenko, V., Egberts, K., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Gabici, S., Giavitto, G., Glawion, D., Glicenstein, J. F., Grondin, M. -H., Hinton, J. A., Hofmann, W., Holch, T. L., Holler, M., Horns, D., Huang, Zhiqiu, Jamrozy, M., Jankowsky, F., Kasai, E., Katarzynski, K., Katz, U., Khelifi, B., Kluzniak, W., Komin, Nu., Kosack, K., Kostunin, D., Lamanna, G., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Malyshev, D., Marandon, V., Marchegiani, P., Martı-Devesa, G., Marx, R., Maurin, G., Meyer, M., Mitchell, A., Moderski, R., Montanari, A., Moulin, E., Muller, J., de Naurois, M., Niemiec, J., Noel, A. Priyana, Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Poireau, V., Prokoph, H., Puhlhofer, G., Punch, M., Quirrenbach, A., Reichherzer, P., Reimer, A., Reimer, O., Renaud, M., Rieger, F., Rowell, G., Rudak, B., Ricarte, H. Rueda, Ruiz-Velasco, E., Sahakian, V., Salzmann, H., Santangelo, A., Sasaki, M., Schussler, F., Schutte, H. M., Schwanke, U., Senniappan, M., Shapopi, J. N. S., Sol, H., Specovius, A., Spencer, S., Stawarz, L., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tanaka, T., Terrier, R., Thorpe-Morgan, C., Tluczykont, M., Tsirou, M., Tsuji, N., Uchiyama, Y., van Eldik, C., Veh, J., Vink, J., Wagner, S. J., White, R., Wierzcholska, A., Wong, Yu Wun, Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zouari, S., and Zywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The central region of the Milky Way is one of the foremost locations to look for dark matter (DM) signatures. We report the first results on a search for DM particle annihilation signals using new observations from an unprecedented gamma-ray survey of the Galactic Center (GC) region, ${\it i.e.}$, the Inner Galaxy Survey, at very high energies ($\gtrsim$ 100 GeV) performed with the H.E.S.S. array of five ground-based Cherenkov telescopes. No significant gamma-ray excess is found in the search region of the 2014-2020 dataset and a profile likelihood ratio analysis is carried out to set exclusion limits on the annihilation cross section $\langle \sigma v\rangle$. Assuming Einasto and Navarro-Frenk-White (NFW) DM density profiles at the GC, these constraints are the strongest obtained so far in the TeV DM mass range. For the Einasto profile, the constraints reach $\langle \sigma v\rangle$ values of $\rm 3.7\times10^{-26} cm^3s^{-1}$ for 1.5 TeV DM mass in the $W^+W^-$ annihilation channel, and $\rm 1.2 \times 10^{-26} cm^3s^{-1}$ for 0.7 TeV DM mass in the $\tau^+\tau^-$ annihilation channel. With the H.E.S.S. Inner Galaxy Survey, ground-based $\gamma$-ray observations thus probe $\langle \sigma v\rangle$ values expected from thermal-relic annihilating TeV DM particles., Comment: Accepted in Phys. Rev. Lett., includes Supplemental materials. 5+10 pages, 2+8 figures, 4 tables
Published: 2022
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26. Gamma-ray emission from the Sagittarius Dwarf Spheroidal galaxy due to millisecond pulsars

Author: Crocker, Roland M., Macias, Oscar, Mackey, Dougal, Krumholz, Mark R., Ando, Shin'ichiro, Horiuchi, Shunsaku, Baring, Matthew G., Gordon, Chris, Venville, Thomas, Duffy, Alan R., Yang, Rui-Zhi, Aharonian, Felix, Hinton, J. A., Song, Deheng, Ruiter, Ashley J., and Filipović, Miroslav D.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract: The Fermi Bubbles are giant, gamma-ray emitting lobes emanating from the nucleus of the Milky Way discovered in ~1-100 GeV data collected by the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope. Previous work has revealed substructure within the Fermi Bubbles that has been interpreted as a signature of collimated outflows from the Galaxy's super-massive black hole. Here we show via a spatial template analysis that much of the gamma-ray emission associated to the brightest region of substructure -- the so-called cocoon -- is likely due to the Sagittarius dwarf spheroidal (Sgr dSph) galaxy. This large Milky Way satellite is viewed through the Fermi Bubbles from the position of the Solar System. As a tidally and ram-pressure stripped remnant, the Sgr dSph has no on-going star formation, but we nevertheless demonstrate that the dwarf's millisecond pulsar (MSP) population can plausibly supply the gamma-ray signal that our analysis associates to its stellar template. The measured spectrum is naturally explained by inverse Compton scattering of cosmic microwave background photons by high-energy electron-positron pairs injected by MSPs belonging to the Sgr dSph, combined with these objects' magnetospheric emission. This finding plausibly suggests that MSPs produce significant gamma-ray emission amongst old stellar populations, potentially confounding indirect dark matter searches in regions such as the Galactic Centre, the Andromeda galaxy, and other massive Milky Way dwarf spheroidals., Comment: Updated to match version accepted for publication in Nature Astronomy (2022). 14 pages main text, 3 main figures, 7 extended data figures. For published version of the paper, see https://rdcu.be/cUZ6X
Published: 2022
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27. CTC and CT5TEA: An advanced multi-channel digitizer and trigger ASIC for imaging atmospheric Cherenkov telescopes

Author: Schwab, B., Zink, A., Varner, G., Depaoli, D., Hinton, J., Liu, G., Okumura, A., Ross, D., Schäfer, J., Schoorlemmer, H., Tajima, H., Vandenbroucke, J., White, R., Watson, J.J., Zorn, J., and Funk, S.
Published: 2024
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28. Validation of standardized data formats and tools for ground-level particle-based gamma-ray observatories

Author: Albert, A., Alfaro, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Babu, R., Belmont-Moreno, E., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Chaparro-Amaro, O., Cotti, U., Cotzomi, J., de León, S. Coutiño, De la Fuente, E., Hernandez, R. Diaz, DuVernois, M. A., Durocher, M., Espinoza, C., Fan, K. L., Alonso, M. Fernández, Fraija, N., García-González, J. A., Goksu, H., González, M. M., Goodman, J. A., Harding, J. P., Hinton, J., Huang, D., Hueyotl-Zahuantitla, F., Hüntemeyer, P., Jardin-Blicq, A., Joshi, V., Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Malone, K., Marandon, V., Martinez, O., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Nisa, M. U., Noriega-Papaqui, R., Olivera-Nieto, L., Pérez-Pérez, E. G., Rho, C. D., Rosa-González, D., Ruiz-Velasco, E., Salazar-Gallegos, D., Greus, F. Salesa, Sandoval, A., Schoorlemmer, H., Serna-Franco, J., Smith, A. J., Son, Y., Springer, R. W., Tollefson, K., Torres, I., Torres-Escobedo, R., Turner, R., Ureña-Mena, F., Villaseñor, L., Wang, X., Watson, I. J., Willox, E., Zhou, H., de León, C., Zepeda, A., Donath, A., and Funk, S.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: Ground-based gamma-ray astronomy is still a rather young field of research, with strong historical connections to particle physics. This is why most observations are conducted by experiments with proprietary data and analysis software, as it is usual in the particle physics field. However in recent years, this paradigm has been slowly shifting towards the development and use of open-source data formats and tools, driven by upcoming observatories such as the Cherenkov Telescope Array (CTA). In this context, a community-driven, shared data format (the gamma-astro-data-format or GADF) and analysis tools such as Gammapy and ctools have been developed. So far these efforts have been led by the IACT community, leaving out other types of ground-based gamma-ray instruments.We aim to show that the data from ground particle arrays, such as the High-Altitude Water Cherenkov (HAWC) observatory, is also compatible with the GADF and can thus be fully analysed using the related tools, in this case Gammapy. We reproduce several published HAWC results using Gammapy and data products compliant with GADF standard. We also illustrate the capabilities of the shared format and tools by producing a joint fit of the Crab spectrum including data from six different gamma-ray experiments. We find excellent agreement with the reference results, a powerful check of both the published results and the tools involved. The data from particle detector arrays such as the HAWC observatory can be adapted to the GADF and thus analysed with Gammapy. A common data format and shared analysis tools allow multi-instrument joint analysis and effective data sharing. Given the complementary nature of pointing and wide-field instruments, this synergy will be distinctly beneficial for the joint scientific exploitation of future observatories such as the Southern Wide-field Gamma-ray Observatory and CTA., Comment: Accepted by A&A
Published: 2022
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29. Time-resolved hadronic particle acceleration in the recurrent Nova RS Ophiuchi

Author: Collaboration, H. E. S. S., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Breuhaus, M., Brose, R., Brun, F., Caroff, S., Casanova, S., Cerruti, M., Chand, T., Chen, A., Cotter, G., Mbarubucyeye, J. Damascene, Djannati-Ataï, A., Dmytriiev, A., Doroshenko, V., Duffy, C., Egberts, K., Ernenwein, J. -P., Fegan, S., Feijen, K., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Füßling, M., Funk, S., Gabici, S., Gallant, Y. A., Ghafourizadeh, S., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Grondin, M. -H., Hermann, G., Hinton, J. A., Hörbe, M., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huang, Zhiqiu, Jamrozy, M., Jankowsky, F., Jung-Richardt, I., Kasai, E., Katarzyński, K., Katz, U., Khangulyan, D., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Stum, S. Le, Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Martí-Devesa, G., Marx, R., Maurin, G., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Muller, J., Murach, T., Nakashima, K., de Naurois, M., Nayerhoda, A., Niemiec, J., Noel, A. Priyana, O'Brien, P., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Pita, S., Poireau, V., Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Reichherzer, P., Reimer, A., Reimer, O., Renaud, M., Reville, B., Rieger, F., Rowell, G., Rudak, B., Ricarte, H. Rueda, Ruiz-Velasco, E., Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Schäfer, J., Schüssler, F., Schutte, H. M., Schwanke, U., Senniappan, M., Shapopi, J. N. S., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spencer, S., Stawarz, Ł., Steinmassl, S., Steppa, C., Takahashi, T., Tanaka, T., Taylor, A. M., Terrier, R., Thorpe-Morgan, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., Unbehaun, T., van Eldik, C., van Soelen, B., Veh, J., Venter, C., Vink, J., Wagner, S. J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yusafzai, A., Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zouari, S., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Recurrent Novae are repeating thermonuclear explosions in the outer layers of white dwarfs, due to the accretion of fresh material from a binary companion. The shock generated by ejected material slamming into the companion star's wind, accelerates particles to very-high-energies. We report very-high-energy (VHE, $\gtrsim100$\,GeV) gamma rays from the recurrent nova RS\,Ophiuchi up to a month after its 2021 outburst, using the High Energy Stereoscopic System. The VHE emission has a similar temporal profile to lower-energy GeV emission, indicating a common origin, with a two-day delay in peak flux. These observations constrain models of time-dependent particle energization, favouring a hadronic emission scenario over the leptonic alternative. This confirms that shocks in dense winds provide favourable environments for efficient cosmic-ray acceleration to very-high-energies., Comment: Submitted 1st Nov. 2021, first release 10th March 2022 (accepted version)
Published: 2022
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30. Gamma-ray halos around pulsars as the key to understanding cosmic ray transport in the Galaxy

Author: López-Coto, R., Wilhelmi, E. de Oña, Aharonian, F., Amato, E., and Hinton, J.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Pulsars are factories of relativistic electrons and positrons that propagate away from the pulsar, permeating later our Galaxy. The acceleration and propagation of these particles are a matter of intense debate. In the last few years, we had the opportunity to directly observing the injection of these particles into the interstellar medium through the discovery of gamma-ray halos around pulsars. This new type of gamma-ray source is produced by electrons and positrons diffusing out of the pulsar wind nebula and scattering ambient photon fields to produce gamma rays. This new field of study comes with a number of observations and constraints at different wavelengths and a variety of theoretical models explaining the characteristics of these halos. We examine the characteristics of the propagation of cosmic rays inferred from the observations of halos and their local and global implications on particle transport in the Galaxy. We also discuss the prospects for observations of these sources with facilities such as LHAASO, or CTA or SWGO in the near future., Comment: Published in Nature Astronomy; authors' version. Link to the paper in https://rdcu.be/cGZ1T
Published: 2022
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31. $\gamma$-ray Emission from Classical Nova V392 Per: Measurements from Fermi and HAWC

Author: Albert, A., Alfaro, R., Alvarez, C., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Babu, R., Belmont-Moreno, E., Blochwitz, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Chaparro-Amaro, O., Cotti, U., Cotzomi, J., de León, E. De la Fuente. C. de León. S. Coutiño, Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Durocher, M., Díaz-Vélez, J. C., Engel, K., Espinoza, C., Fan, K. L., Fang, K., Fraija, N., García-González, J. A., Garfias, F., González, M. M., Goodman, J. A., Harding, J. P., Hernandez, S., Hinton, J., Huang, D., Hueyotl-Zahuantitla, F., Hüntemeyer, P., Iriarte, A., Joshi, V., Lara, A., Lee, W. H., Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Lundeen, J., Malone, K., Marandon, V., Martinez, O., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Omodei, N., Peisker, A., Araujo, Y. Pérez, Pérez-Pérez, E. G., Rho, C. D., Rosa-González, D., Ruiz-Velasco, E., Salazar-Gallegos, D., Greus, F. Salesa, Serna-Franco, A. Sandoval. J., Smith, A. J., Son, Y., Springer, R. W., Tibolla, O., Tollefson, K., Torres, I., Torres-Escobedo, R., Turner, R., Ureña-Mena, F., Villaseñor, L., Wang, X., Willox, E., Zhou, A. Zepeda. H., Chomiuk, L., Aydi, E., Li, K. L., Metzger, B. D., and Vurm, I.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: This paper reports on the $\gamma$-ray properties of the 2018 Galactic nova V392 Per, spanning photon energies $\sim$0.1 GeV to 100 TeV by combining observations from the Fermi Gamma-ray Space Telescope and the HAWC Observatory. In one of the most rapidly evolving $\gamma$-ray signals yet observed for a nova, GeV $\gamma$ rays with a power law spectrum with index $\Gamma = 2.0 \pm 0.1$ were detected over eight days following V392 Per's optical maximum. HAWC observations constrain the TeV $\gamma$-ray signal during this time and also before and after. We observe no statistically significant evidence of TeV $\gamma$-ray emission from V392 Per, but present flux limits. Tests of the extension of the Fermi/LAT spectrum to energies above 5 TeV are disfavored by 2 standard deviations (95\%) or more. We fit V392 Per's GeV $\gamma$ rays with hadronic acceleration models, incorporating optical observations, and compare the calculations with HAWC limits., Comment: 18 pages, 14 figures; revised for referee comments; section 5 revised
Published: 2022
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32. Galactic gamma-ray and neutrino emission from interacting cosmic-ray nuclei

Author: Breuhaus, M., Hinton, J. A., Joshi, V., Reville, B., and Schoorlemmer, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present a study of the expectations for very-high-energy (VHE) to ultra-high-energy (UHE) gamma-ray and neutrino emission from interacting cosmic rays in our Galaxy as well as a comparison to the latest results for the Galactic UHE diffuse emission. We demonstrate the importance of properly accounting for both the mixed cosmic-ray composition and the gamma-ray absorption. We adopt the wounded-nucleon model of nucleus interactions and provide parameterisations of the resulting gamma-ray and neutrino production. Nucleon shielding due to clustering inside nuclei is shown to have a measurable effect on the production of gamma rays and is particularly evident close to breaks and cutoffs in mixed-composition particle spectra. The change in composition around the `knee' in the cosmic ray spectrum has a noticeable impact on the diffuse neutrino and gamma-ray emission spectra. We show that current and near-future detectors can probe these differences in the key energy range from 10 TeV to 1 PeV, testing the paradigm of the universality of the cosmic ray spectrum and composition throughout the Galaxy., Comment: 17 pages, 12 figures, accepted for publication by A&A
Published: 2022
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33. H.E.S.S. follow-up observations of Binary Black Hole Coalescence events during the second and third Gravitational Waves observing runs of Advanced LIGO and Advanced Virgo

Author: collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Brose, R., Brun, F., Bulik, T., Bylund, T., Cangemi, F., Caroff, S., Casanova, S., Chand, T., Chen, A., Cotter, G., Mbarubucyeye, J. Damascene, Devin, J., Djannati-AtaÏ, A., Egberts, K., Ernenwein, J. -P., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Gabici, S., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Grondin, M. -H., Hinton, J. A., Hörbe, M., Hofmann, W., Holch, T. L., Holler, M., Huang, Zhiqiu, Huber, D., Jamrozy, M., Jankowsky, F., Jung-Richardt, I., Kasai, E., Katarzyński, K., Katz, U., Khélifi, B., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kundu, A., Lamanna, G., Stum, S. Le, Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A., Mohrmann, L., Montanari, A., Moulin, E., Muller, J., Murach, T., de Naurois, M., Nayerhoda, A., Niemiec, J., Noel, A. Priyana, O'Brien, P., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panter, M., Parsons, R. D., Peron, G., Poireau, V., Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Reichherzer, P., Renaud, M., Rieger, F., Rowell, G., Rudak, B., Ricarte, H. Rueda, Velasco, E. Ruiz, Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Schüssler, F., Schutte, H. M., Schwanke, U., Senniappan, M., Shapopi, J. N. S., Sinha, A., Sol, H., Specovius, A., Spencer, S., Stawarz, L., Steinmassl, S., Steppa, C., Sun, L., Takahashi, T., Tanaka, T., Terrier, R., Thorpe-Morgan, C., Tsirou, M., Tsuji, N., Uchiyama, Y., van Eldik, C., Veh, J., Vink, J., Wagner, S. J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zouari, S., and Zywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on the observations of four well-localized binary black hole (BBH) mergers by the High Energy Stereoscopic System (H.E.S.S.) during the second and third observing runs of Advanced LIGO and Advanced Virgo, O2 and O3. H.E.S.S. can observe $\mathrm{20\,deg^2}$ of the sky at a time and follows up gravitational-wave (GW) events by ``tiling'' localization regions to maximize the covered localization probability. During O2 and O3, H.E.S.S. observed large portions of the localization regions, between 35\% and 75\%, for four BBH mergers (GW170814, GW190512\_180714, GW190728\_064510, and S200224ca). For these four GW events, we find no significant signal from a pointlike source in any of the observations, and set upper limits on the very high energy ($>$100 GeV) $\gamma$-ray emission. The 1-10 TeV isotropic luminosity of these GW events is below $10^{45}$ erg s$^{-1}$ at the times of the H.E.S.S. observations, around the level of the low-luminosity GRB 190829A. Assuming no changes are made to how follow-up observations are conducted, H.E.S.S. can expect to observe over 60 GW events per year in the fourth GW observing run, O4, of which eight would be observable with minimal latency.
Published: 2021
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34. HAWC Study of the Ultra-High-Energy Spectrum of MGRO J1908+06

Author: HAWC Collaboration, Albert, A., Alfaro, R., Alvarez, C., Álvarez, J. D., Camacho, J. R. Angeles, Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Babu, R., Belmont-Moreno, E., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Cotti, U., Cotzomi, J., de León, S. Coutiño, De la Fuente, E., de León, C., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Durocher, M., Díaz-Vélez, J. C., Engel, K., Espinoza, C., Fan, K. L., Fang, K., Alonso, M. Fernández, Fraija, N., Garcia, D., García-González, J. A., Garfias, F., Giacinti, G., Goksu, H., González, M. M., Goodman, J. A., Harding, J. P., Hinton, J., Hona, B., Huang, D., Hueyotl-Zahuantitla, F., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kieda, D., Lee, W. H., Lee, J., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Malone, K., Marandon, V., Martinez, O., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Olivera-Nieto, L., Omodei, N., Peisker, A., Araujo, Y. Pérez, Pérez-Pérez, E. G., Rho, C. D., Rosa-González, D., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Serna-Franco, J., Smith, A. J., Son, Y., Springer, R. W., Tibolla, O., Tollefson, K., Torres, I., Torres-Escobedo, R., Turner, R., Ureña-Mena, F., Villaseñor, L., Wang, X., Watson, I. J., Willox, E., Zepeda, A., Zhou, H., Li, M. Breuhaus H., and Zhang, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report TeV gamma-ray observations of the ultra-high-energy source MGRO J1908+06 using data from the High Altitude Water Cherenkov (HAWC) Observatory. This source is one of the highest-energy known gamma-ray sources, with emission extending past 200 TeV. Modeling suggests that the bulk of the TeV gamma-ray emission is leptonic in nature, driven by the energetic radio-faint pulsar PSR J1907+0602. Depending on what assumptions are included in the model, a hadronic component may also be allowed. Using the results of the modeling, we discuss implications for detection prospects by multi-messenger campaigns., Comment: accepted by ApJ, in press
Published: 2021
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35. Searching for TeV gamma-ray emission from SGR\,1935+2154 during its 2020 X-ray and radio bursting phase

Author: Collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Anguner, E. O., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlohr, K., Bi, B., Bottcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Breuhaus, M., Brose, R., Brun, F., Brun, P., Bryan, M., Buchele, M., Bulik, T., Bylund, T., Cangemi, F., Caroff, S., Carosi, A., Casanova, S., Chambery, P., Chand, T., Chandra, S., Chen, A., Cotter, G., lo, M. Cury, Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Deil, C., Devin, J., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dreyer, L., Duffy, C., Plessis, L. Du, Dyks, J., Egberts, K., Eichhorn, F., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Ghafourizade, S., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Grondin, M. -H., Hahn, J., Haupt, M., Hattingh, S., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horbe, M., Horns, D., Huang, Z., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kasai, E., Kastendieck, M. A., Katarzyński, K., Katz, U., Khangulyan, D., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Mezek, G. Kukec, Kundu, A., Lamanna, G., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Stum, S. Le, Leuschner, F., Levy, C., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Reville, B., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ricarte, H. Rueda, Ruiz-Velasco, E., Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Schäfer, J., Schüssler, F., Schutte, H. M., Schwanke, U., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shapopi, J. N. S., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Spackman, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, L., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tanaka, T., Tavernier, T., Taylor, A. M., Terrier, R., Thiersen, J. H. E., Thorpe-Morgan, C., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Völk, H. J., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., deWilt, P., Wong, Yu Wun, Yassin, H., Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zorn, J., Zouari, S., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Magnetar hyperflares are the most plausible explanation for fast radio bursts (FRB) -- enigmatic powerful radio pulses with durations of several milliseconds and high brightness temperatures. The first observational evidence for this scenario was obtained in 2020 April when a FRB was detected from the direction of the Galactic magnetar and soft gamma-ray repeater SGR\,1935+2154. The FRB was preceded by two gamma-ray outburst alerts by the BAT instrument aboard the Swift satellite, which triggered follow-up observations by the High Energy Stereoscopic System (H.E.S.S.). H.E.S.S. has observed SGR\,1935+2154 for 2 hr on 2020 April 28. The observations are coincident with X-ray bursts from the magnetar detected by INTEGRAL and Fermi-GBM, thus providing the first very high energy (VHE) gamma-ray observations of a magnetar in a flaring state. High-quality data acquired during these follow-up observations allow us to perform a search for short-time transients. No significant signal at energies $E>0.6$~TeV is found and upper limits on the persistent and transient emission are derived. We here present the analysis of these observations and discuss the obtained results and prospects of the H.E.S.S. follow-up program for soft gamma-ray repeaters., Comment: Received 2021 June 13; accepted 2021 June 28; published 2021 September 29
Published: 2021
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36. Observation of the gamma-ray binary HESS J0632+057 with the H.E.S.S., MAGIC, and VERITAS telescopes

Author: Adams, C. B., Benbow, W., Brill, A., Buckley, J. H., Capasso, M., Chromey, A. J., Errando, M., Falcone, A., Farrell, K. A., Feng, Q., Finley, J P., Foote, G., Fortson, L., Furniss, A., Gent, A., Gillanders, G. H., Giuri, C., Gueta, O., Hanna, D., Hassan, T., Hervet, O., Holder, J., Hona, B., Humensky, T. B., Jin, W., Kaaret, P., Kertzman, M., Kieda, D., Kleiner, T. K., Krennrich, F., Kumar, S., Lang, M. J., Lundy, M., Maier, G., McGrath, C. E., Moriarty, P., Mukherjee, R., Nieto, D., Nievas-Rosillo, M., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Patel, S., Pfrang, K., Pichel, A., Pohl, M., Prado, R. R., Quinn, J., Ragan, K., Reynolds, P. T., Ribeiro, D., Roache, E., Rovero, A. C., Ryan, J. L., Santander, M., Schlenstedt, S., Sembroski, G. H., Shang, R., Tak, D., Vassiliev, V. V., Weinstein, A., Williams, D. A., Williamson, T. J., Acciari, V. A., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Artero, M., Asano, K., Baack, D., Babić, A., Baquero, A., de Almeida, U. Barres, Barrio, J. A., Batković, I., González, J. Becerra, Bednarek, W., Bellizzi, L., Bernardini, E., Bernardos, M., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bökenkamp, H., Bonnol, G., Bošnjak, Ž., Busetto, G., Carosi, R., Ceribella, G., Cerruti, M., Chai, Y., Chilingarian, A., Cikota, S., Colak, S. M., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Mendez, C. Delgado, Depaoli, D., Di Pierro, F., Di Venere, L., Espiñeira, E. Do Souto, Prester, D. Dominis, Donini, A., Dorner, D., Doro, M., Elsaesser, D., Ramazani, V. Fallah, Fattorini, A., Fonseca, M. V., Font, L., Fruck, C., Fukami, S., Fukazawa, Y., López, R. J. García, Garczarczyk, M., Gasparyan, S., Gaug, M., Giglietto, N., Giordano, F., Gliwny, P., Godinović, N., Green, J. G., Green, D., Hadasch, D., Hahn, A., Heckmann, L., Herrera, J., Hoang, J., Hrupec, D., Hütten, M., Inada, T., Ishio, K., Iwamura, Y., Martínez, I. Jiménez, Jormanainen, J., Jouvin, L., Karjalainen, M., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Linhoff, L., Lombardi, S., Longo, F., López-Coto, R., López-Moya, M., López-Oramas, A., Loporchio, S., Fraga, B. Machado de Oliveira, Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Menchiari, S., Mender, S., Mićanović, S., Miceli, D., Miener, T., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Nakamori, T., Nava, L., Neustroev, V., Nigro, C., Nilsson, K., Nishijima, K., Nozaki, K. Noda S., Ohtani, Y., Oka, T., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavletić, L., Peñil, P., Persic, M., Pihet, M., Moroni, P. G. Prada, Prandini, E., Priyadarshi, C., Puljak, I., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Saturni, F. G., Schleicher, B., Schmidt, K., Schweizer, T., Sitarek, J., Šnidarić, I., Spolon, D. Sobczynska A., Stamerra, A., Strišković, J., Strom, D., Strzys, M., Suda, Y., Surić, T., Takahashi, M., Takeishi, R., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Tosti, L., Truzzi, S., Tutone, A., Ubach, S., van Scherpenberg, J., Vanzo, G., Acosta, M. Vazquez, Ventura, S., Verguilov, V., Vigorito, C. F., Vitale, V., Vovk, I., Will, M., Wunderlich, C., Yamamoto, T., Zarić, D., Abdalla, H., Aharonian, F., Ait-Benkhali, F., Anguener, O., Arcaro, C., Ashkar, H., Backes, M., Martins, V. Barbosa, Barnard, M., Batzofin, R., Becherini, Y., Berge, D., Bernloehr, K., Bi, B., Boettcher, M., Boisson, C., Bolmont, J., de Bony, M., Breuhaus, M., Brose, R., Brun, F., Bulik, T., Caroff, S., Casanova, S., Chand, T., Chen, A., Cotter, G., Mbarubucyeye, J. Damascene, Devin, J., Djannati-Atai, A., Egberts, K., Ernenwein, J., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Fuessling, M., Funk, S., Gabici, S., Giavitto, G., Glawion, D., Glicenstein, J., Grondin, M., Hinton, J., Hofmann, W., Holch, T., Holler, M., Horns, D., Huang, Z., Jamrozy, M., Jankowsky, F., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzynski, K., Khelifi, B., Komin, N., Kosack, K., Kostunin, D., Stum, S. Le, Lemiere, A., Lenain, J., Leuschner, F., Levy, C., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Marti'i-Devesa, G., Marx, R., Maurin, G., Meintjes, P., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Muller, J., Murach, T., de Naurois, M., Nayerhoda, A., Niemiec, J., Noel, A., O'Brien, P., Ohm, S., Olivera-Nieto, L., de Ona-Wilhelmi, E., Ostrowski, M., Panny, S., Panter, M., Parsons, D., Peron, G., Poireau, V., Prokhorov, D., Prokoph, H., Puehlhofer, G., Punch, M., Quirrenbach, A., Reichherzer, P., Reimer, A., Reimer, O., Renaud, M., Rieger, F., Romoli, C., Rowell, G., Rudak, B., Ricarte, H. Rueda, Velasco, E. Ruiz, Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D., Santangelo, A., Sasaki, M., Schuessler, F., Schutte, H., Schwanke, U., Senniappan, M., Shapopi, J., Simoni, R., Sol, H., Specovius, A., Spencer, S., Steenkamp, R., Steinmassl, S., Sun, L., Takahashi, T., Tanaka, T., Terrier, R., Tsuji, N., Uchiyama, Y., van Eldik, C., van Soelen, B., Veh, J., Venter, C., Vink, J., Wagner, S., White, R., Wierzcholska, A., Wong, Y. W., Zacharias, M., Zargaryan, D., Zdziarski, A., Zech, A., Zhu, S., Zouari, S., Zywucka, N., Moritani, Y., and Torres, D. F.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The results of gamma-ray observations of the binary system HESS J0632+057 collected during 450 hours over 15 years, between 2004 and 2019, are presented. Data taken with the atmospheric Cherenkov telescopes H.E.S.S., MAGIC, and VERITAS at energies above 350 GeV were used together with observations at X-ray energies obtained with Swift-XRT, Chandra, XMM-Newton, NuSTAR, and Suzaku. Some of these observations were accompanied by measurements of the H{\alpha} emission line. A significant detection of the modulation of the VHE gamma-ray fluxes with a period of 316.7+-4.4 days is reported, consistent with the period of 317.3+-0.7 days obtained with a refined analysis of X-ray data. The analysis of data of four orbital cycles with dense observational coverage reveals short timescale variability, with flux-decay timescales of less than 20 days at very high energies. Flux variations observed over the time scale of several years indicate orbit-to-orbit variability. The analysis confirms the previously reported correlation of X-ray and gamma-ray emission from the system at very high significance, but can not find any correlation of optical H{\alpha} parameters with X-ray or gamma-ray energy fluxes in simultaneous observations. The key finding is that the emission of HESS J0632+057 in the X-ray and gamma-ray energy bands is highly variable on different time scales. The ratio of gamma-ray to X-ray flux shows the equality or even dominance of the gamma-ray energy range. This wealth of new data is interpreted taking into account the insufficient knowledge of the ephemeris of the system, and discussed in the context of results reported on other gamma-ray binary systems., Comment: Accepted for publication by The Astrophysical Journal
Published: 2021
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37. A pulsar wind nebula origin of the LHAASO-detected UHE gamma-ray sources

Author: Breuhaus, M., Reville, B., and Hinton, J. A.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The recent measurement by LHAASO of gamma-ray emission extending up to 100s of TeV from multiple Galactic sources represents a major observational step forward in the search for the origin of the Galactic cosmic rays. The burning question is if this ultra-high-energy emission is associated to acceleration of protons and/or nuclei to PeV energies, or can be associated to PeV-electron accelerators. A strong Klein-Nishina suppression of inverse Compton emission at these energies is unavoidable, nevertheless we show here that inverse Compton emission can provide a natural explanation of the measured emission, and that an association to the established PeV-electron accelerating source class of pulsar wind nebulae is also rather natural. However, a clear distinction between different models requires taking into account multi-wavelength data, having good knowledge about the local environmental conditions and, in some cases, to perform multi-source modeling., Comment: 5 pages, 3 figures
Published: 2021
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38. Detection of extended TeV emission around the Geminga pulsar with H.E.S.S

Author: Mitchell, A. M. W., Caroff, S., Hinton, J., and Mohrmann, L.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Highly extended gamma-ray emission around the Geminga pulsar was discovered by Milagro and verified by HAWC. Despite many observations with Imaging Atmospheric Cherenkov Telescopes (IACTs), detection of gamma-ray emission on angular scales exceeding the IACT field-of-view has proven challenging. Recent developments in analysis techniques have enabled the detection of significant emission around Geminga in archival data with H.E.S.S.. In 2019, further data on the Geminga region were obtained with an adapted observation strategy. Following the announcement of the detection of significant TeV emission around Geminga in archival data, in this contribution we present the detection in an independent dataset. New analysis results will be presented, and emphasis given to the technical challenges involved in observations of highly extended gamma-ray emission with IACTs., Comment: 8 pages, 4 figures, Proceedings of the 37th International Cosmic Ray Conference (ICRC2021)
Published: 2021

39. LMC N132D: A mature supernova remnant with a power-law gamma-ray spectrum extending beyond 8 TeV

Author: Collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Breuhaus, M., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Casanova, S., Chand, T., Chandra, S., Chen, A., Cotter, G., Curyło, M., Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Deil, C., Devin, J., Dirson, L., Djannati-Atai, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dreyer, L., Duffy, C., Dyks, J., Egberts, K., Eichhorn, F., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Grondin, M. -H., Hahn, J., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Hörbe, M., Horns, D., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kasai, E., Kastendieck, M. A., Katarzynski, K., Katz, U., Khangulyan, D., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Scalici, M., Schäfer, J., Schüssler, F., Schutte, H. M., Schwanke, U., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shapopi, J. N. S., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, L., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Thiersen, J. H. E., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Völk, H. J., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zorn, J., Zouari, S., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We analyzed 252 hours of High Energy Stereoscopic System (H.E.S.S.) observations towards the supernova remnant (SNR) LMC N132D that were accumulated between December 2004 and March 2016 during a deep survey of the Large Magellanic Cloud, adding 104 hours of observations to the previously published data set to ensure a > 5 sigma detection. To broaden the gamma-ray spectral coverage required for modeling the spectral energy distribution, an analysis of Fermi-LAT Pass 8 data was also included. We unambiguously detect N132D at very high energies (VHE) with a significance of 5.7 sigma. We report the results of a detailed analysis of its spectrum and localization based on the extended H.E.S.S. data set. The joint analysis of the extended H.E.S.S and Fermi-LAT data results in a spectral energy distribution in the energy range from 1.7 GeV to 14.8 TeV, which suggests a high luminosity of N132D at GeV and TeV energies. We set a lower limit on a gamma-ray cutoff energy of 8 TeV with a confidence level of 95%. The new gamma-ray spectrum as well as multiwavelength observations of N132D when compared to physical models suggests a hadronic origin of the VHE gamma-ray emission. SNR N132D is a VHE gamma-ray source that shows a spectrum extending to the VHE domain without a spectral cutoff at a few TeV, unlike the younger oxygen-rich SNR Cassiopeia A. The gamma-ray properties of N132D may be affected by an interaction with a nearby molecular cloud that partially lies inside the 95% confidence region of the source position. [Abridged], Comment: Accepted for publication in Astronomy & Astrophysics
Published: 2021
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40. LEGEND-1000 Preconceptual Design Report

Author: LEGEND Collaboration, Abgrall, N., Abt, I., Agostini, M., Alexander, A., Andreoiu, C., Araujo, G. R., Avignone III, F. T., Bae, W., Bakalyarov, A., Balata, M., Bantel, M., Barabanov, I., Barabash, A. S., Barbeau, P. S., Barton, C. J., Barton, P. J., Baudis, L., Bauer, C., Bernieri, E., Bezrukov, L., Bhimani, K. H., Biancacci, V., Blalock, E., Bolozdynya, A., Borden, S., Bos, B., Bossio, E., Boston, A., Bothe, V., Bouabid, R., Boyd, S., Brugnera, R., Burlac, N., Busch, M., Caldwell, A., Caldwell, T. S., Carney, R., Cattadori, C., Chan, Y. -D., Chernogorov, A., Christofferson, C. D., Chu, P. -H., Clark, M., Cohen, T., Combs, D., Comellato, T., Cooper, R. J., Costa, I. A., D'Andrea, V., Detwiler, J. A., Di Giacinto, A., Di Marco, N., Dobson, J., Drobizhev, A., Durand, M. R., Edzards, F., Efremenko, Yu., Elliott, S. R., Engelhardt, A., Fajt, L., Faud, N., Febbraro, M. T., Ferella, F., Fields, D. E., Fischer, F., Fomina, M., Fox, H., Franchi, J., Gala, R., Galindo-Uribarri, A., Gangapshev, A., Garfagnini, A., Geraci, A., Gilbert, C., Gold, M., Gooch, C., Gradwohl, K. P., Green, M. P., Grinyer, G. F., Grobov, A., Gruszko, J., Guinn, I., Guiseppe, V. E., Gurentsov, V., Gurov, Y., Gusev, K., Hacket, B., Hagemann, F., Hakenmüeller, J., Haranczyk, M., Hauertmann, L., Haufe, C. R., Hayward, C., Heffron, B., Henkes, F., Henning, R., Aguilar, D. Hervas, Hinton, J., Hodak, R., Hoffmann, H., Hofmann, W., Hostiuc, A., Huang, J., Hult, M., Mirza, M. Ibrahim, Jochum, J., Jones, R., Judson, D., Junker, M., Kaizer, J., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kidd, M., Kihm, T., Kilgus, K., Kim, I., Klimenko, A., Knöpfle, K. T., Kochetov, O., Konovalov, S. I., Kontul, I., Kool, K., Kormos, L. L., Kornoukhov, V. N., Korosec, M., Krause, P., Kuzminov, V. V., López-Castaño, J. M., Lang, K., Laubenstein, M., León, E., Lehnert, B., Leonhardt, A., Li, A., Lindner, M., Lippi, I., Liu, X., Liu, J., Loomba, D., Lubashevskiy, A., Lubsandorzhiev, B., Lusardi, N., Müller, Y., Macko, M., Macolino, C., Majorovits, B., Mamedov, F., Maneschg, W., Manzanillas, L., Marshall, G., Martin, R. D., Martin, E. L., Massarczyk, R., Mei, D., Meijer, S. J., Mertens, S., Misiaszek, M., Mondragon, E., Morella, M., Morgan, B., Mroz, T., Muenstermann, D., Nave, C. J., Nemchenok, I., Neuberger, M., Oli, T. K., Gann, G. Orebi, Othman, G., Palušova, V., Panth, R., Papp, L., Paudel, L. S., Pelczar, K., Perez, J. Perez, Pertoldi, L., Pettus, W., Piseri, P., Poon, A. W. P., Povinec, P., Pullia, A., Radford, D. C., Ramachers, Y. A., Ransom, C., Rauscher, L., Redchuk, M., Reine, A. L., Riboldi, S., Rielage, K., Rozov, S., Rukhadze, E., Rumyantseva, N., Runge, J., Ruof, N. W., Saakyan, R., Sailer, S., Salamanna, G., Salamida, F., Salvat, D. J., Sandukovsky, V., Schönert, S., Schültz, A., Schütt, M., Schaper, D. C., Schreiner, J., Schulz, O., Schuster, M., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shafiee, M., Shevchik, E., Shirchenko, M., Shitov, Y., Simgen, H., Simkovic, F., Skorokhvatov, M., Slavickova, M., Smolek, K., Smolnikov, A., Solomon, J. A., Song, G., Starosta, K., Stekl, I., Stommel, M., Stukov, D., Sumathi, R. R., Sweigart, D. A., Szczepaniec, K., Taffarello, L., Tagnani, D., Tayloe, R., Tedeschi, D., Turqueti, M., Varner, R. L., Vasilyev, S., Veresnikova, A., Vetter, K., Vignoli, C., Vogl, C., von Sturm, K., Waters, D., Waters, J. C., Wei, W., Wiesinger, C., Wilkerson, J. F., Willers, M., Wiseman, C., Wojcik, M., Wu, V. H. -S., Xu, W., Yakushev, E., Ye, T., Yu, C. -H., Yumatov, V., Zaretski, N., Zeman, J., Zhitnikov, I., Zinatulina, D., Zschocke, A. -K., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: We propose the construction of LEGEND-1000, the ton-scale Large Enriched Germanium Experiment for Neutrinoless $\beta \beta$ Decay. This international experiment is designed to answer one of the highest priority questions in fundamental physics. It consists of 1000 kg of Ge detectors enriched to more than 90% in the $^{76}$Ge isotope operated in a liquid argon active shield at a deep underground laboratory. By combining the lowest background levels with the best energy resolution in the field, LEGEND-1000 will perform a quasi-background-free search and can make an unambiguous discovery of neutrinoless double-beta decay with just a handful of counts at the decay $Q$ value. The experiment is designed to probe this decay with a 99.7%-CL discovery sensitivity in the $^{76}$Ge half-life of $1.3\times10^{28}$ years, corresponding to an effective Majorana mass upper limit in the range of 9-21 meV, to cover the inverted-ordering neutrino mass scale with 10 yr of live time.
Published: 2021

41. TeV emission of Galactic plane sources with HAWC and H.E.S.S

Author: Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Breuhaus, M., Brose, R., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Chand, T., Chandra, S., Chen, A., Cotter, G., Curyło, M., Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Deil, C., Devin, J., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dreyer, L., Duffy, C., Dyks, J., Egberts, K., Eichhorn, F., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Hörbe, M., Horns, D., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jung-Richardt, I., Kasai, E., Kastendieck, M. A., Katarzyński, K., Katz, U., Khangulyan, D., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A. M. W., Moderski, R., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niemiec, J., Oakes, L., Brien, P. O, Odaka, H., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Schäfer, J., Schüssler, F., Schutte, H. M., Schwanke, U., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shapopi, J. N. S., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, Ł., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Thiersen, J. H. E., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Völk, H. J., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zmija, A., Zorn, J., Zouari, S., Żywucka, N., Albert, A., Alfaro, R., Alvarez, C., Arteaga-Velázquez, J. C., Arunbabu, K. P., Rojas, D. Avila, Belmont-Moreno, E., BenZvi, S. Y., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Cotti, U., Cotzomi, J., de León, S. Coutiño, De la Fuente, E., de León, C., Hernandez, R. Diaz, Díaz-Vélez, J. C., Dingus, B. L., DuVernois, M. A., Durocher, M., Ellsworth, R. W., Engel, K., Espinoza, C., Fan, K. L., Alonso, M. Fernández, Fraija, N., Galván-Gámez, A., Garcia, D., García-González, J. A., Garfias, F., Giacinti, G., González, M. M., Goodman, J. A., Harding, J. P., Hernandez, S., Hona, B., Huang, D., Hueyotl-Zahuantitla, F., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kieda, D., Lee, W. H., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., López-Coto, R., Malone, K., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Omodei, N., Peisker, A., Araujo, Y. Pérez, Pérez-Pérez, E. G., Rho, C. D., Rosa-González, D., Ruiz-Velasco, E., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Serna-Franco, J., Smith, A. J., Springer, R. W., Surajbali, P., Tollefson, K., Torres, I., Torres-Escobedo, R., Turner, R., Ureña-Mena, F., Villaseñor, L., Weisgarber, T., Willox, E., and Zhou, H.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: The High Altitude Water Cherenkov (HAWC) observatory and the High Energy Stereoscopic System (H.E.S.S.) are two leading instruments in the ground-based very-high-energy gamma-ray domain. HAWC employs the water Cherenkov detection (WCD) technique, while H.E.S.S. is an array of Imaging Atmospheric Cherenkov Telescopes (IACTs). The two facilities therefore differ in multiple aspects, including their observation strategy, the size of their field of view and their angular resolution, leading to different analysis approaches. Until now, it has been unclear if the results of observations by both types of instruments are consistent: several of the recently discovered HAWC sources have been followed up by IACTs, resulting in a confirmed detection only in a minority of cases. With this paper, we go further and try to resolve the tensions between previous results by performing a new analysis of the H.E.S.S. Galactic plane survey data, applying an analysis technique comparable between H.E.S.S. and HAWC. Events above 1 TeV are selected for both datasets, the point spread function of H.E.S.S. is broadened to approach that of HAWC, and a similar background estimation method is used. This is the first detailed comparison of the Galactic plane observed by both instruments. H.E.S.S. can confirm the gamma-ray emission of four HAWC sources among seven previously undetected by IACTs, while the three others have measured fluxes below the sensitivity of the H.E.S.S. dataset. Remaining differences in the overall gamma-ray flux can be explained by the systematic uncertainties. Therefore, we confirm a consistent view of the gamma-ray sky between WCD and IACT techniques.
Published: 2021
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42. Evidence of 100 TeV $\gamma$-ray emission from HESS J1702-420: A new PeVatron candidate

Author: Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Breuhaus, M., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Casanova, S., Chand, T., Chandra, S., Chen, A., Cotter, G., Curyło, M., Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Deil, C., Devin, J., Dirson, L., Djannati-Atai, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dreyer, L., Duffy, C., Dyks, J., Egberts, K., Eichhorn, F., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Grondin, M. -H., Hahn, J., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Hörbe, M., Horns, D., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kasai, E., Kastendieck, M. A., Katarzynski, K., Katz, U., Khangulyan, D., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Scalici, M., Schäfer, J., Schüssler, F., Schutte, H. M., Schwanke, U., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shapopi, J. N. S., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, L., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Thiersen, J. H. E., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Völk, H. J., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zorn, J., Zouari, S., Żywucka, N., and Acero, F.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The identification of PeVatrons, hadronic particle accelerators reaching the knee of the cosmic ray spectrum (few $10^{15}$ eV), is crucial to understand the origin of cosmic rays in the Galaxy. We provide an update on the unidentified source HESS J1702-420, a promising PeVatron candidate. We present new observations of HESS J1702-420 made with the High Energy Stereoscopic System (H.E.S.S.), and processed using improved analysis techniques. The analysis configuration was optimized to enhance the collection area at the highest energies. We applied a three-dimensional (3D) likelihood analysis to model the source region and adjust non thermal radiative spectral models to the $\gamma$-ray data. We also analyzed archival data from the Fermi Large Area Telescope (LAT) to constrain the source spectrum at $\gamma$-ray energies >10 GeV. We report the detection of a new source component called HESS J1702-420A, that was separated from the bulk of TeV emission at a $5.4\sigma$ confidence level. The power law $\gamma$-ray spectrum of HESS J1702-420A extends with an index of $\Gamma=1.53\pm0.19_\text{stat}\pm0.20_\text{sys}$ and without curvature up to the energy band 64-113 TeV, in which it was detected by H.E.S.S. at a $4.0\sigma$ confidence level. This brings evidence for the source emission up to $100\,\text{TeV}$, which makes HESS J1702-420A a compelling candidate site for the presence of extremely high energy cosmic rays. Remarkably, in a hadronic scenario, the cut-off energy of the proton distribution powering HESS J1702-420A is found to be higher than 0.5 PeV at a 95% confidence level. HESS J1702-420A becomes therefore one of the most solid PeVatron candidates detected so far in H.E.S.S. data, altough a leptonic origin of its emission could not be ruled out either., Comment: Accepted for publication in the 2. Astrophysical processes section of Astronomy & Astrophysics
Published: 2021
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43. Search for dark matter annihilation signals from unidentified Fermi-LAT objects with H.E.S.S

Author: Collaboration, H. E. S. S., Abdallah, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Breuhaus, M., Brose, R., Brun, F., Bulik, T., Bylund, T., Cangemi, F., Caroff, S., Casanova, S., Chambery, P., Chand, J. Catalano T., Chen, A., Cotter, G., Curylo, M., Dalgleish, H., Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Devin, J., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dreyer, L., Plessis, L. Du, Duffy, C., Egberts, K., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Grondin, M. -H., Hattingh, S., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Hörbe, M., Horns, D., Huang, Z., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzyński, K., Katz, U., Khangulyan, D., Khèlifi, B., Klepser, S., Kluzniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Mezek, G. Kukec, Kundu, A., Lamanna, G., Stum, S. Le, Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Levy, C., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Martì-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niemiec, J., Noel, A., Oberholzer, L., O'Brien, P., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panter, M., Panny, S., Parsons, R. D., Peron, G., Pita, S., Poireau, V., Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Romoli, C., Rowell, G., Rudak, B., Ricarte, H. Rueda, Ruiz-Velasco, E., Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Schüssler, F., Schutte, H. M., Schwanke, U., Senniappan, M., Seyffert, A. S., Shapopi, J. N. S., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Spackman, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, L., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tanaka, T., Tavernier, T., Taylor, A. M., Terrier, R., Morgan, C. Thorpe, Thiersen, J. H. E., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tsuji, M., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Viana, A., Vincent, P., Vink, J., Völk, H. J., Wagner, S. J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yassin, H., Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S., Zmija, A., Zorn, J., Zouari, S., and Zywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Cosmological $N$-body simulations show that Milky Way-sized galaxies harbor a population of unmerged dark matter subhalos. These subhalos could shine in gamma-rays and be eventually detected in gamma-ray surveys as unidentified sources. We performed a thorough selection among unidentified Fermi-LAT Objects (UFOs) to identify them as possible TeV-scale dark matter subhalo candidates. We search for very-high-energy (E $\gtrsim$ 100 GeV) gamma-ray emissions using H.E.S.S. observations towards four selected UFOs. Since no significant very-high-energy gamma-ray emission is detected in any dataset of the four observed UFOs nor in the combined UFO dataset, strong constraints are derived on the product of the velocity-weighted annihilation cross section $\langle \sigma v \rangle$ by the $J$-factor for the dark matter models. The 95% C.L. observed upper limits derived from combined H.E.S.S. observations reach $\langle \sigma v \rangle J$ values of 3.7$\times$10$^{-5}$ and 8.1$\times$10$^{-6}$ GeV$^2$cm$^{-2}$s$^{-1}$ in the $W^+W^-$ and $\tau^+\tau^-$ channels, respectively, for a 1 TeV dark matter mass. Focusing on thermal WIMPs, the H.E.S.S. constraints restrict the $J$-factors to lie in the range 6.1$\times$10$^{19}$ - 2.0$\times$10$^{21}$ GeV$^2$cm$^{-5}$, and the masses to lie between 0.2 and 6 TeV in the $W^+W^-$ channel. For the $\tau^+\tau^-$ channel, the $J$-factors lie in the range 7.0$\times$10$^{19}$ - 7.1$\times$10$^{20}$ GeV$^2$cm$^{-5}$ and the masses lie between 0.2 and 0.5 TeV. Assuming model-dependent predictions from cosmological N-body simulations on the $J$-factor distribution for Milky Way-sized galaxies, the dark matter models with masses greater than 0.3 TeV for the UFO emissions can be ruled out at high confidence level., Comment: 11 pages, 7 figures, matches accepted version in The Astrophysical Journal
Published: 2021
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44. Search for dark matter annihilation in the dwarf irregular galaxy WLM with H.E.S.S

Author: Collaboration, H. E. S. S., Abdallah, H., Adam, R., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Breuhaus, M., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Casanova, S., Chand, T., Chandra, S., Chen, A., Cotter, G., Curylo, M., Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Duffy, C., Dyks, J., Egberts, K., Eichhorn, F., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Hörbe, M., Horns, D., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kasai, E., Kastendieck, M. A., Katarzyński, K., Katz, U., Khangulyan, D., Khèlifi, B., Klepser, S., Kluzniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Martì-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Moderski, R., Mohamed, M., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panter, M., Panny, S., Parsons, R. D., Peron, G., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Sailer, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Scalici, M., Schüssler, F., Schutte, H. M., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, L., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S., Zorn, J., Zouari, S., and Zywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract: We search for an indirect signal of dark matter through very high-energy gamma rays from the Wolf-Lundmark-Melotte (WLM) dwarf irregular galaxy. The pair annihilation of dark matter particles would produce Standard Model particles in the final state such as gamma rays, which might be detected by ground-based Cherenkov telescopes. Dwarf irregular galaxies represent promising targets as they are dark matter dominated objects with well measured kinematics and small uncertainties on their dark matter distribution profiles. In 2018, the H.E.S.S. five-telescope array observed the dwarf irregular galaxy WLM for 18 hours. We present the first analysis based on data obtained from an imaging atmospheric Cherenkov telescope for this subclass of dwarf galaxy. As we do not observe any significant excess in the direction of WLM, we interpret the result in terms of constraints on the velocity-weighted cross section for dark matter pair annihilation as a function of the dark matter particle mass for various continuum channels as well as the prompt gamma-gamma emission. For the $\tau^+\tau^-$ channel the limits reach a $\langle \sigma v \rangle$ value of about $4\times 10^{-22}$ cm3s-1 for a dark matter particle mass of 1 TeV. For the prompt gamma-gamma channel, the upper limit reaches a $\langle \sigma v \rangle$ value of about $5 \times10^{-24}$ cm3s-1 for a mass of 370 GeV. These limits represent an improvement of up to a factor 200 with respect to previous results for the dwarf irregular galaxies for TeV dark matter search., Comment: 13 pages, 5 figures
Published: 2021
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45. HAWC observations of the acceleration of very-high-energy cosmic rays in the Cygnus Cocoon

Author: Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Camacho, J. R. Angeles, Arteaga-Velazquez, J. C., Arunbabu, K. P., Rojas, D. Avila, Solares, H. A. Ayala, Baghmanyan, V., Belmont-Moreno, E., BenZvi, S. Y., Blandford, R., Brisbois, C., Caballero-Mora, K. S., Capistran, T., Carraminana, A., Casanova, S., Cotti, U., de Leon, S. Coutino, De la Fuente, E., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Durocher, M., Diaz-Velez, J. C., Ellsworth, R. W., Engel, K., Espinoza, C., Fan, K. L., Fang, K., Fleischhack, H., Fraija, N., Galvan-Gamez, A., Garcia, D., Garcıa-Gonzalez, J. A., Garfias, F., Giacinti, G., Gonzalez, M. M., Goodman, J. A., Harding, J. P., Hernandez, S., Hinton, J., Hona, B., Huang, D., Hueyotl-Zahuantitla, F., Huntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kieda, D., Lara, A., Lee, W. H., Vargas, H. Leon, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Lundeen, J., Malone, K., Martinez, O., Martinez-Castellanos, I., Martinez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Soto, J. A. Morales, Moreno, E., Mostafa, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Olivera-Nieto, L., Omodei, N., Peisker, A., Araujo, Y. Perez, Perez-Perez, E. G., Ren, Z., Rho, C. D., Rosa-Gonzalez, D., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandova, A., Schneider, M., Schoorlemmer, H., Serna, F., Smith, A. J., Springer, R. W., Surajbali, P., Tollefson, K., Torres, I., Torres-Escobedo, R., Urena-Mena, F., Weisgarber, T., Werner, F., Willox, E., Zepeda, A., Zhou, H., on, C. De Le, and Alvarez, J. D.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Cosmic rays with energies up to a few PeV are known to be accelerated within the Milky Way. Traditionally, it has been presumed that supernova remnants were the main source of very-high-energy cosmic rays but theoretically it is difficult to get protons to PeV energies and observationally there simply is no evidence to support the remnants as sources of hadrons with energies above a few tens of TeV. One possible source of protons with those energies is the Galactic Center region. Here we report observations of 1-100 TeV gamma rays coming from the 'Cygnus Cocoon', which is a superbubble surrounding a region of OB2 massive star formation. These gamma rays are likely produced by 10-1000 TeV freshly accelerated CRs originating from the enclosed star forming region Cygnus OB2. Hitherto it was not known that such regions could accelerate particles to these energies. The measured flux is likely originated by hadronic interactions. The spectral shape and the emission profile of the Cocoon changes from GeV to TeV energies, which reveals the transport of cosmic particles and historical activity in the superbubble.
Published: 2021
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46. Spectrum and Morphology of the Very-High-Energy Source HAWC J2019+368

Author: HAWC Collaboration, Albert, A., Alfaro, R., Alvarez, C., Arteaga-Velàzquez, J. C., Arunbabu, K. P., Rojas, D. Avila, Solares, H. A. Ayala, Baghmanyan, V., Belmont-Moreno, E., Brisbois, C., Caballero-Mora, K. S., Capistràn, T., Carramiñana, A., Casanova, S., Cotzomi, J., de León, S. Coutinõ, De la Fuente, E., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Durocher, M., Engel, K., Espinoza, C., Fraija, N., Garcia, D., García-González, J. A., Giacinti, G., González, M. M., Goodman, J. A., Harding, J. P., Hinton, J., Hona, B., Huang, D., Hueyotl-Zahuantitla, F., Huentemeyer, P., Jardin-Blicq, A., Joshi, V., Lee, W. H., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Lundeen, J., López-Coto, R., Malone, K., Martinez, O., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Olivera-Nieto, L., Omodei, N., Peisker, A., Araujo, Y. Pérez, Pérez-Pérez, E. G., Rho, C. D., Rosa-Gonzàlez, D., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Serna-Franco, J., Smith, A. J., Springer, R. W., Surajbali, P., Tollefson, K., Torres, I., Turner, R., Urenã-Mena, F., Weisgarber, T., Willox, E., Zhou, H., and de León, C.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The MGRO J2019+37 region is one of the brightest sources in the sky at TeV energies. It was detected in the 2 year HAWC catalog as 2HWC J2019+367 and here we present a detailed study of this region using data from HAWC. This analysis resolves the region into two sources: HAWC J2019+368 and HAWC J2016+371. We associate HAWC J2016+371 with the evolved supernova remnant CTB 87, although its low significance in this analysis prevents a detailed study at this time. An investigation of the morphology (including possible energy dependent morphology) and spectrum for HAWC J2019+368 is the focus of this work. We associate HAWC J2019+368 with PSR J2021+3651 and its X-ray pulsar wind nebula, the Dragonfly nebula. Modeling the spectrum measured by HAWC and Suzaku reveals a $\sim$7 kyr pulsar and nebula system producing the observed emission at X-ray and ${\gamma}$-ray energies., Comment: Submitted to ApJ: 13 pages, 10 figures
Published: 2021

47. Observation of a sudden cessation of a very-high-energy gamma-ray flare in PKS 1510-089 with H.E.S.S. and MAGIC in May 2016

Author: Collaboration, H. E. S. S., Abdalla, H., Adam, R., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arcaro, C., Arm, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., de Lavergne, M. de Bony, Bregeon, J., Breuhaus, M., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Casanova, S., Ch, T., Ch, S., Chen, A., Cotter, G., Curyło, M., Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dyks, J., Egberts, K., Eichhorn, F., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Filipovic, M., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Hörbe, M., Horns, D., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katz, U., Khangulyan, D., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Mar, V., Marchegiani, P., Marcowith, A., Mares, A., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panter, M., Panny, S., Parsons, R. D., Peron, G., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Sailer, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Scalici, M., Schüssler, F., Schutte, H. M., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, Ł., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zorn, J., Zouari, S., Żywucka, N., Collaboration, MAGIC, Acciari, V. A., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Asano, K., Baack, D., Babić, A., Baquero, A., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bellizzi, L., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Bil, A., Blanch, O., Bonnoli, G., Bošnjak, Ž., Busetto, G., Carosi, R., Ceribella, G., Cerruti, M., Chai, Y., Chilingarian, A., Cikota, S., Colak, S. M., Colin, U., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Depaoli, D., Di Pierro, F., Di Venere, L., neira, E. Do Souto Espi\, Prester, D. Dominis, Donini, A., Dorner, D., Doro, M., Elsaesser, D., Ramazani, V. Fallah, Fattorini, A., Ferrara, G., Foffano, L., Fonseca, M. V., Font, L., Fruck, C., Fukami, S., López, R. J. García, Garczarczyk, M., Gasparyan, S., Gaug, M., Giglietto, N., Giordano, F., Gliwny, P., Godinović, N., Green, D., Hadasch, D., Hahn, A., Heckmann, L., Herrera, J., Hoang, J., Hrupec, D., Hütten, M., Inada, T., Inoue, S., Ishio, K., Iwamura, Y., Jouvin, L., Kajiwara, Y., Karjalainen, M., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., López, M., López-Coto, R., López-Oramas, A., Loporchio, S., Fraga, B. Machado de Oliveira, Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Mender, S., Mićanović, S., Miceli, D., Miener, T., Minev, M., Mir, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Munar-Adrover, P., Neustroev, V., Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nozaki, S., Ohtani, Y., Oka, T., Otero-Santos, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavletić, L., nil, P. Pe\, Perennes, C., Persic, M., Moroni, P. G. Prada, Pr, E., Priyadarshi, C., Puljak, I., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Schleicher, B., Schmidt, K., Schweizer, T., Sitarek, J., Šnidarić, I., Sobczynska, D., Spolon, A., Stamerra, A., Strom, D., Strzys, M., Suda, Y., Surić, T., Takahashi, M., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Torres-Albà, N., Tosti, L., Truzzi, S., van Scherpenberg, J., Vanzo, G., Acosta, M. Vazquez, Ventura, S., Verguilov, V., Vigorito, C. F., Vitale, V., Vovk, I., Will, M., Zarić, D., Jorstad, S. G., Marscher, A. P., Boccardi, B., Casadio, C., Hodgson, J., Kim, J. -Y., Krichbaum, T. P., Lähteenmäki, A., Tornikoski, M., Traianou, E., and Weaver, Z. R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract: The flat spectrum radio quasar (FSRQ) PKS 1510-089 is known for its complex multiwavelength behavior, and is one of only a few FSRQs detected at very high energy (VHE, $E>100\,$GeV) $\gamma$-rays. VHE $\gamma$-ray observations with H.E.S.S. and MAGIC during late May and early June 2016 resulted in the detection of an unprecedented flare, which reveals for the first time VHE $\gamma$-ray intranight variability in this source. While a common variability timescale of $1.5\,$hr is found, there is a significant deviation near the end of the flare with a timescale of $\sim 20\,$min marking the cessation of the event. The peak flux is nearly two orders of magnitude above the low-level emission. For the first time, curvature is detected in the VHE $\gamma$-ray spectrum of PKS 1510-089, which is fully explained through absorption by the extragalactic background light. Optical R-band observations with ATOM reveal a counterpart of the $\gamma$-ray flare, even though the detailed flux evolution differs from the VHE ightcurve. Interestingly, a steep flux decrease is observed at the same time as the cessation of the VHE flare. In the high energy (HE, $E>100\,$MeV) $\gamma$-ray band only a moderate flux increase is observed with Fermi-LAT, while the HE $\gamma$-ray spectrum significantly hardens up to a photon index of 1.6. A search for broad-line region (BLR) absorption features in the $\gamma$-ray spectrum indicates that the emission region is located outside of the BLR. Radio VLBI observations reveal a fast moving knot interacting with a standing jet feature around the time of the flare. As the standing feature is located $\sim 50\,$pc from the black hole, the emission region of the flare may have been located at a significant distance from the black hole. If this correlation is indeed true, VHE $\gamma$ rays have been produced far down the jet where turbulent plasma crosses a standing shock., Comment: 25 pages, 17 figures. Accepted for publication by Astronomy & Astrophysics. Corresponding authors: M. Zacharias, J. Sitarek, D. Sanchez, T. Terzic
Published: 2020
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48. Ultra-high energy Inverse Compton emission from Galactic electron accelerators

Author: Breuhaus, M., Hahn, J., Romoli, C., Reville, B., Giacinti, G., Tuffs, R., and Hinton, J. A.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: It is generally held that >100 TeV emission from astrophysical objects unambiguously demonstrates the presence of PeV protons or nuclei, due to the unavoidable Klein-Nishina suppression of inverse Compton emission from electrons. However, in the presence of inverse Compton dominated cooling, hard high-energy electron spectra are possible. We show that the environmental requirements for such spectra can naturally be met in spiral arms, and in particular in regions of enhanced star formation activity, the natural locations for the most promising electron accelerators: powerful young pulsars. Our scenario suggests a population of hard ultra-high energy sources is likely to be revealed in future searches, and may also provide a natural explanation for the 100 TeV sources recently reported by HAWC., Comment: Accepted for publication in ApJL
Published: 2020
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49. An extreme particle accelerator in the Galactic plane: HESS J1826$-$130

Author: Collaboration, H. E. S. S., Abdalla, H., Adam, R., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Bordas, P., Breuhaus, M., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Casanova, S., Chand, T., Chandra, S., Chen, A., Cotter, G., Curyło, M., Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Duffy, C., Dyks, J., Egberts, K., Eichhorn, F., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Hörbe, M., Horns, D., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kasai, E., Kastendieck, M. A., Katarzyński, K., Katz, U., Khangulyan, D., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A., Moderski, R., Mohamed, M., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Oya, I., Panter, M., Panny, S., Parsons, R. D., Peron, G., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Sailer, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Scalici, M., Schüssler, F., Schutte, H. M., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, Ł., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Ziegler, A., Zorn, J., Zouari, S., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The unidentified very-high-energy (VHE; E $>$ 0.1 TeV) $\gamma$-ray source, HESS J1826$-$130, was discovered with the High Energy Stereoscopic System (HESS) in the Galactic plane. The analysis of 215 h of HESS data has revealed a steady $\gamma$-ray flux from HESS J1826$-$130, which appears extended with a half-width of 0.21$^{\circ}$ $\pm$ 0.02$^{\circ}_{\text{stat}}$ $\pm$ 0.05$^{\circ}_{\text{sys}}$. The source spectrum is best fit with either a power-law function with a spectral index $\Gamma$ = 1.78 $\pm$ 0.10$_{\text{stat}}$ $\pm$ 0.20$_{\text{sys}}$ and an exponential cut-off at 15.2$^{+5.5}_{-3.2}$ TeV, or a broken power-law with $\Gamma_{1}$ = 1.96 $\pm$ 0.06$_{\text{stat}}$ $\pm$ 0.20$_{\text{sys}}$, $\Gamma_{2}$ = 3.59 $\pm$ 0.69$_{\text{stat}}$ $\pm$ 0.20$_{\text{sys}}$ for energies below and above $E_{\rm{br}}$ = 11.2 $\pm$ 2.7 TeV, respectively. The VHE flux from HESS J1826$-$130 is contaminated by the extended emission of the bright, nearby pulsar wind nebula (PWN), HESS J1825$-$137, particularly at the low end of the energy spectrum. Leptonic scenarios for the origin of HESS J1826$-$130 VHE emission related to PSR J1826$-$1256 are confronted by our spectral and morphological analysis. In a hadronic framework, taking into account the properties of dense gas regions surrounding HESS J1826$-$130, the source spectrum would imply an astrophysical object capable of accelerating the parent particle population up to $\gtrsim$200 TeV. Our results are also discussed in a multiwavelength context, accounting for both the presence of nearby supernova remnants (SNRs), molecular clouds, and counterparts detected in radio, X-rays, and TeV energies., Comment: 9 Pages, 5 Figures
Published: 2020
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50. Sensitivity of the Cherenkov Telescope Array for probing cosmology and fundamental physics with gamma-ray propagation

Author: Consortium, The Cherenkov Telescope Array, Abdalla, H., Abe, H., Acero, F., Acharyya, A., Adam, R., Agudo, I., Aguirre-Santaella, A., Alfaro, R., Alfaro, J., Alispach, C., Aloisio, R., B, R. Alves, Amati, L., Amato, E., Ambrosi, G., Angüner, E. O., Araudo, A., Armstrong, T., Arqueros, F., Arrabito, L., Asano, K., Ascasíbar, Y., Ashley, M., Backes, M., Balazs, C., Balbo, M., Balmaverde, B., Larriva, A. Baquero, Martins, V. Barbosa, Barkov, M., Baroncelli, L., de Almeida, U. Barres, Barrio, J. A., Batista, P., Becerra, J., Becherini, Y., Beck, G., Tjus, J. Becker, Belmont, R., Benbow, W., Bernardini, E., Berti, A., Berton, M., Bertucci, B., Beshley, V., Bi, B., Biasuzzi, B., Biland, A., Bissaldi, E., Biteau, J., Blanch, O., Bocchino, F., Boisson, C., Bolmont, J., Bonanno, G., Arbeletche, L. Bonneau, Bonnoli, G., Bordas, P., Bottacini, E., Böttcher, M., Bozhilov, V., Bregeon, J., Brill, A., Brown, A. M., Bruno, P., Bruno, A., Bulgarelli, A., Burton, M., Buscemi, M., Caccianiga, A., Cameron, R., Capasso, M., Caprai, M., Caproni, A., Capuzzo-Dolcetta, R., Caraveo, P., Carosi, R., Carosi, A., Casanova, S., Cascone, E., Cauz, D., Cerny, K., Cerruti, M., Chadwick, P., Chaty, S., Chen, A., Chernyakova, M., Chiaro, G., Chiavassa, A., Chytka, L., Conforti, V., Conte, F., Contreras, J. L., Coronado-Blazquez, J., Cortina, J., Costa, A., Costantini, H., Covino, S., Cristofari, P., Cuevas, O., D'Ammando, F., Daniel, M. K., Davies, J., Dazzi, F., De Angelis, A., de Lavergne, M. de Bony, De Caprio, V., Anjos, R. de Cássia dos, Pino, E. M. de Gouveia Dal, De Lotto, B., De Martino, D., de Naurois, M., Wilhelmi, E. de Oña, De Palma, F., de Souza, V., Delgado, C., Della Ceca, R., della Volpe, D., Depaoli, D., Di Girolamo, T., Di Pierro, F., Díaz, C., Díaz-Bahamondes, C., Diebold, S., Djannati-Ataï, A., Dmytriiev, A., Domínguez, A., Donini, A., Dorner, D., Doro, M., Dournaux, J., Dwarkadas, V. V., Ebr, J., Eckner, C., Einecke, S., Ekoume, T. R. N., Elsässer, D., Emery, G., Evoli, C., Fairbairn, M., Falceta-Goncalves, D., Fegan, S., Feng, Q., Ferrand, G., Fiandrini, E., Fiasson, A., Fioretti, V., Foffano, L., Fonseca, M. V., Font, L., Fontaine, G., Franco, F. J., Coromina, L. Freixas, Fukami, S., Fukazawa, Y., Fukui, Y., Gaggero, D., Galanti, G., Gammaldi, V., Garcia, E., Garczarczyk, M., Gascon, D., Gaug, M., Gent, A., Ghalumyan, A., Ghirlanda, G., Gianotti, F., Giarrusso, M., Giavitto, G., Giglietto, N., Giordano, F., Glicenstein, J., Goldoni, P., González, J. M., Gourgouliatos, K., Grabarczyk, T., Grandi, P., Granot, J., Grasso, D., Green, J., Grube, J., Gueta, O., Gunji, S., Halim, A., Harvey, M., Collado, T. Hassan, Hayashi, K., Heller, M., Cadena, S. Hernández, Hervet, O., Hinton, J., Hiroshima, N., Hnatyk, B., Hnatyk, R., Hoffmann, D., Hofmann, W., Holder, J., Horan, D., Hörandel, J., Horvath, P., Hovatta, T., Hrabovsky, M., Hrupec, D., Hughes, G., Hütten, M., Iarlori, M., Inada, T., Inoue, S., Insolia, A., Ionica, M., Iori, M., Jacquemont, M., Jamrozy, M., Janecek, P., Martínez, I. Jiménez, Jin, W., Jung-Richardt, I., Jurysek, J., Kaaret, P., Karas, V., Karkar, S., Kawanaka, N., Kerszberg, D., Khélifi, B., Kissmann, R., Knödlseder, J., Kobayashi, Y., Kohri, K., Komin, N., Kong, A., Kosack, K., Kubo, H., La Palombara, N., Lamanna, G., Lang, R. G., Lapington, J., Laporte, P., Lemoine-Goumard, M., Lenain, J., Leone, F., Leto, G., Leuschner, F., Lindfors, E., Lloyd, S., Lohse, T., Lombardi, S., Longo, F., Lopez, A., López, M., López-Coto, R., Loporchio, S., Lucarelli, F., Luque-Escamilla, P. L., Lyard, E., Maggio, C., Majczyna, A., Makariev, M., Mallamaci, M., Mandat, D., Maneva, G., Manganaro, M., Manicò, G., Marcowith, A., Marculewicz, M., Markoff, S., Marquez, P., Martí, J., Martinez, O., Martínez, M., Martínez, G., Martínez-Huerta, H., Maurin, G., Mazin, D., Mbarubucyeye, J. D., Miranda, D. Medina, Meyer, M., Micanovic, S., Miener, T., Minev, M., Miranda, J. M., Mitchell, A., Mizuno, T., Mode, B., Moderski, R., Mohrmann, L., Molina, E., Montaruli, T., Moralejo, A., Merino, J. Morales, Morcuende-Parrilla, D., Morselli, A., Mukherjee, R., Mundell, C., Murach, T., Muraishi, H., Nagai, A., Nakamori, T., Nemmen, R., Niemiec, J., Nieto, D., Nievas, M., Nikołajuk, M., Nishijima, K., Noda, K., Nosek, D., Nozaki, S., O'Brien, P., Ohira, Y., Ohishi, M., Oka, T., Ong, R. A., Orienti, M., Orito, R., Orlandini, M., Orlando, E., Osborne, J. P., Ostrowski, M., Oya, I., Pagliaro, A., Palatka, M., Paneque, D., Pantaleo, F. R., Paredes, J. M., Parmiggiani, N., Patricelli, B., Pavletić, L., Pe'er, A., Pech, M., Pecimotika, M., Peresano, M., Persic, M., Petruk, O., Pfrang, K., Piatteli, P., Pietropaolo, E., Pillera, R., Pilszyk, B., Pimentel, D., Pintore, F., Pita, S., Pohl, M., Poireau, V., Polo, M., Prado, R. R., Prast, J., Principe, G., Produit, N., Prokoph, H., Prouza, M., Przybilski, H., Pueschel, E., Pühlhofer, G., Pumo, M. L., Punch, M., Queiroz, F., Quirrenbach, A., Rando, R., Razzaque, S., Rebert, E., Recchia, S., Reichherzer, P., Reimer, O., Reimer, A., Renier, Y., Reposeur, T., Rhode, W., Ribeiro, D., Ribó, M., Richtler, T., Rico, J., Rieger, F., Rizi, V., Rodriguez, J., Fernandez, G. Rodriguez, Ramirez, J. C. Rodriguez, Vázquez, J. J. Rodríguez, Romano, P., Romeo, G., Roncadelli, M., Rosado, J., de Leon, A. Rosales, Rowell, G., Rudak, B., Rujopakarn, W., Russo, F., Sadeh, I., Saha, L., Saito, T., Greus, F. Salesa, Sanchez, D., Sánchez-Conde, M., Sangiorgi, P., Sano, H., Santander, M., Santos, E. M., Sanuy, A., Sarkar, S., Saturni, F. G., Sawangwit, U., Scherer, A., Schleicher, B., Schovanek, P., Schussler, F., Schwanke, U., Sciacca, E., Scuderi, S., Arroyo, M. Seglar, Sergijenko, O., Servillat, M., Seweryn, K., Shalchi, A., Sharma, P., Shellard, R. C., Siejkowski, H., Sinha, A., Sliusar, V., Slowikowska, A., Sokolenko, A., Sol, H., Specovius, A., Spencer, S., Spiga, D., Stamerra, A., Stanič, S., Starling, R., Stolarczyk, T., Straumann, U., Strišković, J., Suda, Y., Świerk, P., Tagliaferri, G., Takahashi, H., Takahashi, M., Tavecchio, F., Taylor, L., Tejedor, L. A., Temnikov, P., Terrier, R., Terzic, T., Testa, V., Tian, W., Tibaldo, L., Tonev, D., Torres, D. F., Torresi, E., Tosti, L., Tothill, N., Tovmassian, G., Travnicek, P., Truzzi, S., Tuossenel, F., Umana, G., Vacula, M., Vagelli, V., Valentino, M., Vallage, B., Vallania, P., van Eldik, C., Varner, G. S., Vassiliev, V., Acosta, M. Vázquez, Vecchi, M., Veh, J., Vercellone, S., Vergani, S., Verguilov, V., Vettolani, G. P., Viana, A., Vigorito, C. F., Vitale, V., Vorobiov, S., Vovk, I., Vuillaume, T., Wagner, S. J., Walter, R., Watson, J., White, M., White, R., Wiemann, R., Wierzcholska, A., Will, M., Williams, D. A., Wischnewski, R., Wolter, A., Yamazaki, R., Yanagita, S., Yang, L., Yoshikoshi, T., Zacharias, M., Zaharijas, G., Zaric, D., Zavrtanik, M., Zavrtanik, D., Zech, A., Zechlin, H., Zhdanov, V. I., and Živec, M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: The Cherenkov Telescope Array (CTA), the new-generation ground-based observatory for $\gamma$-ray astronomy, provides unique capabilities to address significant open questions in astrophysics, cosmology, and fundamental physics. We study some of the salient areas of $\gamma$-ray cosmology that can be explored as part of the Key Science Projects of CTA, through simulated observations of active galactic nuclei (AGN) and of their relativistic jets. Observations of AGN with CTA will enable a measurement of $\gamma$-ray absorption on the extragalactic background light with a statistical uncertainty below 15% up to a redshift $z=2$ and to constrain or detect $\gamma$-ray halos up to intergalactic-magnetic-field strengths of at least 0.3pG. Extragalactic observations with CTA also show promising potential to probe physics beyond the Standard Model. The best limits on Lorentz invariance violation from $\gamma$-ray astronomy will be improved by a factor of at least two to three. CTA will also probe the parameter space in which axion-like particles could constitute a significant fraction, if not all, of dark matter. We conclude on the synergies between CTA and other upcoming facilities that will foster the growth of $\gamma$-ray cosmology., Comment: 71 pages (including affiliations and references), 13 figures, 6 tables. Accepted in JCAP; matches published version. Corresponding authors: Jonathan Biteau, Julien Lefaucheur, Humberto Martinez-Huerta, Manuel Meyer, Santiago Pita, Ievgen Vovk
Published: 2020
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