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22 results on '"E. Willox"'

1. Observation of the Galactic Center PeVatron beyond 100 TeV with HAWC

Author

A. Albert, R. Alfaro, C. Alvarez, A. Andrés, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A. Ayala Solares, R. Babu, E. Belmont-Moreno, A. Bernal, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, U. Cotti, J. Cotzomi, S. Coutiño de León, E. De la Fuente, C. de León, D. Depaoli, N. Di Lalla, R. Diaz Hernandez, B. L. Dingus, M. A. DuVernois, J. C. Díaz-Vélez, K. Engel, T. Ergin, C. Espinoza, K. L. Fan, K. Fang, N. Fraija, S. Fraija, J. A. García-González, F. Garfias, H. Goksu, M. M. González, J. A. Goodman, S. Groetsch, J. P. Harding, S. Hernández-Cadena, I. Herzog, J. Hinton, D. Huang, F. Hueyotl-Zahuantitla, T. B. Humensky, P. Hüntemeyer, A. Iriarte, S. Kaufmann, D. Kieda, A. Lara, W. H. Lee, J. Lee, H. León Vargas, J. T. Linnemann, A. L. Longinotti, G. Luis-Raya, K. Malone, O. Martinez, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, J. A. Montes, J. A. Morales-Soto, E. Moreno, M. Mostafá, M. Najafi, L. Nellen, M. Newbold, M. U. Nisa, R. Noriega-Papaqui, L. Olivera-Nieto, N. Omodei, M. Osorio-Archila, Y. Pérez Araujo, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, E. Ruiz-Velasco, H. Salazar, D. Salazar-Gallegos, A. Sandoval, M. Schneider, G. Schwefer, J. Serna-Franco, A. J. Smith, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Ureña-Mena, E. Varela, X. Wang, Z. Wang, I. J. Watson, E. Willox, H. Wu, S. Yu, S. Yun-Cárcamo, and H. Zhou

Subjects
Galactic center, Gamma-rays, Ultra-high-energy cosmic radiation, Astrophysics, QB460-466
Abstract

We report an observation of ultrahigh-energy (UHE) gamma rays from the Galactic center (GC) region, using 7 yr 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 ( ${d}N/{d}E=\phi {\left(E/26\,\mathrm{TeV}\right)}^{\gamma }$ ), where γ = −2.88 ± 0.15 _stat − 0.1 _sys and ϕ = 1.5 × 10 ^−15 (TeV cm ^2 s) ^−1 $\pm {0.3}_{\mathrm{stat}}{\,}_{-{0.13}_{\mathrm{sys}}}^{+{0.08}_{\mathrm{sys}}}$ 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 σ ), 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 GC.

Published
2024
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2. Search for Joint Multimessenger Signals from Potential Galactic Cosmic-Ray Accelerators with HAWC and IceCube

Author

R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A. Ayala Solares, R. Babu, E. Belmont-Moreno, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, U. Cotti, J. Cotzomi, S. Coutiño de León, E. De la Fuente, D. Depaoli, N. Di Lalla, R. Diaz Hernandez, J. C. Díaz-Vélez, K. Engel, T. Ergin, K. L. Fan, K. Fang, N. Fraija, S. Fraija, J. A. García-González, F. Garfias, M. M. González, J. A. Goodman, S. Groetsch, J. P. Harding, S. Hernández-Cadena, I. Herzog, D. Huang, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, S. Kaufmann, J. Lee, H. León Vargas, G. Luis-Raya, K. Malone, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, J. A. Montes, E. Moreno, M. Mostafá, L. Nellen, M. U. Nisa, N. Omodei, M. Osorio, Y. Pérez Araujo, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, H. Salazar, D. Salazar-Gallegos, A. Sandoval, M. Schneider, J. Serna-Franco, A. J. Smith, Y. Son, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Ureña-Mena, X. Wang, I. J. Watson, K. Whitaker, E. Willox, H. Wu, S. Yu, S. Yun-Cárcamo, H. Zhou, C. de León, HAWC Collaboration, R. Abbasi, M. Ackermann, J. Adams, S. K. Agarwalla, J. A. Aguilar, M. Ahlers, J. M. Alameddine, N. M. Amin, K. Andeen, C. Argüelles, Y. Ashida, S. Athanasiadou, L. Ausborm, S. N. Axani, X. Bai, A. Balagopal V., M. Baricevic, S. W. Barwick, S. Bash, V. Basu, R. Bay, J. J. Beatty, J. Becker Tjus, J. Beise, C. Bellenghi, C. Benning, S. BenZvi, D. Berley, E. Bernardini, D. Z. Besson, E. Blaufuss, L. Bloom, S. Blot, F. Bontempo, J. Y. Book Motzkin, C. Boscolo Meneguolo, S. Böser, O. Botner, J. Böttcher, J. Braun, B. Brinson, J. Brostean-Kaiser, L. Brusa, R. T. Burley, D. Butterfield, M. A. Campana, I. Caracas, K. Carloni, J. Carpio, S. Chattopadhyay, N. Chau, Z. Chen, D. Chirkin, S. Choi, B. A. Clark, A. Coleman, G. H. Collin, A. Connolly, J. M. Conrad, P. Coppin, R. Corley, P. Correa, D. F. Cowen, P. Dave, C. De Clercq, J. J. DeLaunay, D. Delgado, S. Deng, A. Desai, P. Desiati, K. D. de Vries, G. de Wasseige, T. DeYoung, A. Diaz, P. Dierichs, M. Dittmer, A. Domi, L. Draper, H. Dujmovic, K. Dutta, M. A. DuVernois, T. Ehrhardt, L. Eidenschink, A. Eimer, P. Eller, E. Ellinger, S. El Mentawi, D. Elsässer, R. Engel, H. Erpenbeck, J. Evans, P. A. Evenson, K. Farrag, A. R. Fazely, A. Fedynitch, N. Feigl, S. Fiedlschuster, C. Finley, L. Fischer, D. Fox, A. Franckowiak, S. Fukami, P. Fürst, J. Gallagher, E. Ganster, A. Garcia, M. Garcia, G. Garg, E. Genton, L. Gerhardt, A. Ghadimi, C. Girard-Carillo, C. Glaser, T. Glüsenkamp, J. G. Gonzalez, S. Goswami, A. Granados, D. Grant, S. J. Gray, O. Gries, S. Griffin, S. Griswold, K. M. Groth, C. Günther, P. Gutjahr, C. Ha, C. Haack, A. Hallgren, L. Halve, F. Halzen, H. Hamdaoui, M. Ha Minh, M. Handt, K. Hanson, J. Hardin, A. A. Harnisch, P. Hatch, A. Haungs, J. Häußler, K. Helbing, J. Hellrung, J. Hermannsgabner, L. Heuermann, N. Heyer, S. Hickford, A. Hidvegi, C. Hill, G. C. Hill, K. D. Hoffman, S. Hori, K. Hoshina, M. Hostert, W. Hou, T. Huber, K. Hultqvist, M. Hünnefeld, R. Hussain, K. Hymon, A. Ishihara, W. Iwakiri, M. Jacquart, O. Janik, M. Jansson, G. S. Japaridze, M. Jeong, M. Jin, B. J. P. Jones, N. Kamp, D. Kang, W. Kang, X. Kang, A. Kappes, D. Kappesser, L. Kardum, T. Karg, M. Karl, A. Karle, A. Katil, U. Katz, M. Kauer, J. L. Kelley, M. Khanal, A. Khatee Zathul, A. Kheirandish, J. Kiryluk, S. R. Klein, A. Kochocki, R. Koirala, H. Kolanoski, T. Kontrimas, L. Köpke, C. Kopper, D. J. Koskinen, P. Koundal, M. Kovacevich, M. Kowalski, T. Kozynets, J. Krishnamoorthi, K. Kruiswijk, E. Krupczak, A. Kumar, E. Kun, N. Kurahashi, N. Lad, C. Lagunas Gualda, M. Lamoureux, M. J. Larson, S. Latseva, F. Lauber, J. P. Lazar, J. W. Lee, K. Leonard DeHolton, A. Leszczyńska, J. Liao, M. Lincetto, Y. T. Liu, M. Liubarska, E. Lohfink, C. Love, C. J. Lozano Mariscal, L. Lu, F. Lucarelli, W. Luszczak, Y. Lyu, J. Madsen, E. Magnus, K. B. M. Mahn, Y. Makino, E. Manao, S. Mancina, W. Marie Sainte, I. C. Mariş, S. Marka, Z. Marka, M. Marsee, I. Martinez-Soler, R. Maruyama, F. Mayhew, F. McNally, J. V. Mead, K. Meagher, S. Mechbal, A. Medina, M. Meier, Y. Merckx, L. Merten, J. Micallef, J. Mitchell, T. Montaruli, R. W. Moore, Y. Morii, R. Morse, M. Moulai, T. Mukherjee, R. Naab, R. Nagai, M. Nakos, U. Naumann, J. Necker, A. Negi, L. Neste, M. Neumann, H. Niederhausen, K. Noda, A. Noell, A. Novikov, A. Obertacke Pollmann, V. O’Dell, B. Oeyen, A. Olivas, R. Orsoe, J. Osborn, E. O’Sullivan, H. Pandya, N. Park, G. K. Parker, E. N. Paudel, L. Paul, C. Pérez de los Heros, T. Pernice, J. Peterson, S. Philippen, A. Pizzuto, M. Plum, A. Pontén, Y. Popovych, M. Prado Rodriguez, B. Pries, R. Procter-Murphy, G. T. Przybylski, C. Raab, J. Rack-Helleis, M. Ravn, K. Rawlins, Z. Rechav, A. Rehman, P. Reichherzer, E. Resconi, S. Reusch, W. Rhode, B. Riedel, A. Rifaie, E. J. Roberts, S. Robertson, S. Rodan, G. Roellinghoff, M. Rongen, A. Rosted, C. Rott, T. Ruhe, L. Ruohan, D. Ryckbosch, I. Safa, J. Saffer, P. Sampathkumar, A. Sandrock, M. Santander, S. Sarkar, J. Savelberg, P. Savina, P. Schaile, M. Schaufel, H. Schieler, S. Schindler, B. Schlüter, F. Schlüter, N. Schmeisser, T. Schmidt, J. Schneider, F. G. Schröder, L. Schumacher, S. Sclafani, D. Seckel, M. Seikh, M. Seo, S. Seunarine, P. Sevle Myhr, R. Shah, S. Shefali, N. Shimizu, M. Silva, B. Skrzypek, B. Smithers, R. Snihur, J. Soedingrekso, A. Søgaard, D. Soldin, P. Soldin, G. Sommani, C. Spannfellner, G. M. Spiczak, C. Spiering, M. Stamatikos, T. Stanev, T. Stezelberger, T. Stürwald, T. Stuttard, G. W. Sullivan, I. Taboada, S. Ter-Antonyan, A. Terliuk, M. Thiesmeyer, W. G. Thompson, J. Thwaites, S. Tilav, C. Tönnis, S. Toscano, D. Tosi, A. Trettin, R. Turcotte, J. P. Twagirayezu, M. A. Unland Elorrieta, A. K. Upadhyay, K. Upshaw, A. Vaidyanathan, N. Valtonen-Mattila, J. Vandenbroucke, N. van Eijndhoven, D. Vannerom, J. van Santen, J. Vara, J. Veitch-Michaelis, M. Venugopal, M. Vereecken, S. Verpoest, D. Veske, A. Vijai, C. Walck, A. Wang, C. Weaver, P. Weigel, A. Weindl, J. Weldert, A. Y. Wen, C. Wendt, J. Werthebach, M. Weyrauch, N. Whitehorn, C. H. Wiebusch, D. R. Williams, L. Witthaus, A. Wolf, M. Wolf, G. Wrede, X. W. Xu, J. P. Yanez, E. Yildizci, S. Yoshida, R. Young, T. Yuan, Z. Zhang, P. Zhelnin, P. Zilberman, M. Zimmerman, and IceCube Collaboration

Subjects
Neutrino astronomy, Gamma-ray astronomy, Particle astrophysics, High energy astrophysics, Astrophysics, QB460-466
Abstract

The origin of high-energy galactic cosmic rays is yet to be understood, but some galactic cosmic-ray accelerators can accelerate cosmic rays up to PeV energies. The high-energy cosmic rays are expected to interact with the surrounding material or radiation, resulting in the production of gamma-rays and neutrinos. To optimize for the detection of such associated production of gamma-rays and neutrinos for a given source morphology and spectrum, a multimessenger analysis that combines gamma-rays and neutrinos is required. In this study, we use the Multi-Mission Maximum Likelihood framework with IceCube Maximum Likelihood Analysis software and HAWC Accelerated Likelihood to search for a correlation between 22 known gamma-ray sources from the third HAWC gamma-ray catalog and 14 yr of IceCube track-like data. No significant neutrino emission from the direction of the HAWC sources was found. We report the best-fit gamma-ray model and 90% CL neutrino flux limit from the 22 sources. From the neutrino flux limit, we conclude that, for five of the sources, the gamma-ray emission observed by HAWC cannot be produced purely from hadronic interactions. We report the limit for the fraction of gamma-rays produced by hadronic interactions for these five sources.

Published
2024
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3. Precise Measurements of TeV Halos around Geminga and Monogem Pulsars with HAWC

Author

A. Albert, R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A. Ayala Solares, R. Babu, E. Belmont-Moreno, A. Bernal, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, U. Cotti, J. Cotzomi, S. Coutiño de León, E. de la Fuente, D. Depaoli, N. Di Lalla, R. Diaz Hernandez, B. L. Dingus, M. A. DuVernois, M. Durocher, J. C. Díaz-Vélez, K. Engel, C. Espinoza, K. L. Fan, K. Fang, N. Fraija, J. A. García-González, F. Garfias, H. Goksu, M. M. González, J. A. Goodman, S. Groetsch, J. P. Harding, S. Hernández-Cadena, I. Herzog, P. Hüntemeyer, D. Huang, F. Hueyotl-Zahuantitla, A. Iriarte, V. Joshi, S. Kaufmann, D. Kieda, A. Lara, W. H. Lee, J. Lee, H. León Vargas, J. T. Linnemann, A. L. Longinotti, G. Luis-Raya, K. Malone, O. Martinez, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, J. A. Montes, J. A. Morales-Soto, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, R. Noriega-Papaqui, L. Olivera-Nieto, N. Omodei, Y. Pérez Araujo, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, H. Salazar, D. Salazar-Gallegos, A. Sandoval, M. Schneider, G. Schwefer, J. Serna-Franco, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Urea-Mena, E. Varela, L. Villaseñor, X. Wang, I. J. Watson, E. Willox, H. Wu, S. Yun-Cárcamo, H. Zhou, C. de León, HAWC Collaboration, and M. Di Mauro

Subjects
High energy astrophysics, Particle astrophysics, Pulsars, Pulsar wind nebulae, Astrophysics, QB460-466
Abstract

We present the most precise measurements to date for the spatial extension and energy spectrum of the γ -ray region between a pulsar’s wind nebula and the interstellar medium, better known as the halo, present around Geminga and PSR B0656+14 (Monogem) using ∼2398 days of >1 TeV data collected by the HAWC observatory. We interpret the data using a physically motivated model for the diffuse γ -ray emission generated from positrons and electrons (e ^± ) injected by the pulsar wind nebula and inverse Compton scattering with interstellar radiation fields. We find the morphologies of the regions inside these halos are characterized by an inhibited diffusion that are approximately three orders of magnitudes smaller than the Galactic average. We also obtain the e ^± emission efficiencies of 6.6% and 5.1%, respectively, for Geminga and Monogem. These results have remarkable consequences for the study of the particle diffusion in the region between the pulsar wind nebulae and the interstellar medium, and for the interpretation of the flux of positrons measured by the AMS-02 experiment above 10 GeV.

Published
2024
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4. Performance of the HAWC Observatory and TeV Gamma-Ray Measurements of the Crab Nebula with Improved Extensive Air Shower Reconstruction Algorithms

Author

A. Albert, R. Alfaro, C. Alvarez, A. Andrés, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A. Ayala Solares, R. Babu, E. Belmont-Moreno, A. Bernal, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, F. Carreón, S. Casanova, U. Cotti, J. Cotzomi, S. Coutiño de León, E. De la Fuente, C. de León, D. Depaoli, N. Di Lalla, R. Díaz Hernández, B. L. Dingus, M. A. DuVernois, K. Engel, T. Ergin, C. Espinoza, K. L. Fan, K. Fang, N. Fraija, S. Fraija, J. A. García-González, F. Garfias, H. Goksu, M. M. González, J. A. Goodman, S. Groetsch, J. P. Harding, S. Hernández-Cadena, I. Herzog, J. Hinton, D. Huang, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, S. Kaufmann, A. Lara, J. Lee, H. León Vargas, J. T. Linnemann, A. L. Longinotti, G. Luis-Raya, K. Malone, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, J. A. Montes, E. Moreno, M. Mostafá, L. Nellen, M. U. Nisa, R. Noriega-Papaqui, L. Olivera-Nieto, N. Omodei, M. Osorio-Archila, Y. Pérez Araujo, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, E. Ruiz-Velasco, H. Salazar, D. Salazar-Gallegos, A. Sandoval, M. Schneider, G. Schwefer, J. Serna-Franco, A. J. Smith, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Ureña-Mena, E. Varela, X. Wang, I. J. Watson, K. Whitaker, E. Willox, H. Wu, S. Yu, S. Yun-Cárcamo, H. Zhou, and HAWC Collaboration

Subjects
High energy astrophysics, Gamma-rays, Gamma-ray detectors, Astrophysics, QB460-466
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, ${ \mathcal O }(0\buildrel{\circ}\over{.} 1)$ biases in highly inclined showers, and enhancements to the core reconstruction. The angular resolution for gamma rays approaching the HAWC array from large zenith angles (>37°) has improved by a factor of 4 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 χ ^2 values improved the background rejection performance at all inclinations. At large zenith angles, the improvement in significance is a factor of 4 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° zenith is comparable to 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
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5. TeV Analysis of a Source-rich Region with the HAWC Observatory: Is HESS J1809-193 a Potential Hadronic PeVatron?

Author

A. Albert, R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez, D. Avila Rojas, R. Babu, E. Belmont-Moreno, A. Bernal, M. Breuhaus, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, J. Cotzomi, E. De la Fuente, D. Depaoli, N. Di Lalla, R. Diaz Hernandez, B. L. Dingus, M. A. DuVernois, C. Espinoza, K. L. Fan, K. Fang, B. Fick, N. Fraija, J. A. García-González, F. Garfias, A. Gonzalez Muñoz, M. M. González, J. A. Goodman, S. Groetsch, J. P. Harding, S. Hernández-Cadena, I. Herzog, D. Huang, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, V. Joshi, S. Kaufmann, A. Lara, J. Lee, H. León Vargas, A. L. Longinotti, G. Luis-Raya, K. Malone, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, J. A. Montes, J. A. Morales-Soto, E. Moreno, M. Mostafá, L. Nellen, M. Newbold, M. U. Nisa, R. Noriega-Papaqui, M. Osorio, Y. Pérez Araujo, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, E. Ruiz-Velasco, H. Salazar, A. Sandoval, M. Schneider, J. Serna-Franco, A. J. Smith, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Ureña-Mena, E. Varela, X. Wang, I. J. Watson, E. Willox, S. Yun-Cárcamo, H. Zhou, and THE HAWC COLLABORATION

Subjects
Gamma-ray astronomy, Astronomical methods, Gamma-ray sources, Astrophysics, QB460-466
Abstract

HESS J1809-193 is an unidentified TeV source, first detected by the High Energy Stereoscopic System (H.E.S.S.) collaboration. The emission originates in a source-rich region that includes several supernova remnants (SNRs) and pulsars including SNR G11.1+0.1, SNR G11.0-0.0, and the young radio pulsar PSR J1809-1917. Originally classified as a pulsar wind nebula candidate, recent studies show the peak of the TeV region overlapping with a system of molecular clouds. This resulted in the revision of the original leptonic scenario to look for alternate hadronic scenarios. Marked as a potential PeVatron candidate, this region has been studied extensively by H.E.S.S. due to its emission extending up to several tens of TeV. In this work, we use 2398 days of data from the High Altitude Water Cherenkov (HAWC) observatory to carry out a systematic source search of the HESS J1809-193 region. We were able to resolve emission detected as an extended component (modelled as a symmetric Gaussian with a 1 σ radius of 0.°21) with no clear cutoff at high energies and emitting photons up to 210 TeV. We model the multiwavelength observations for the region around HESS J1809-193 using a time-dependent leptonic model and a lepto-hadronic model. Our model indicates that both scenarios could explain the observed data within the region of HESS J1809-193.

Published
2024
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6. Exploring the Coronal Magnetic Field with Galactic Cosmic Rays: The Sun Shadow Observed by HAWC

Author

R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez, K. P. Arunbabu, D. Avila Rojas, R. Babu, E. Belmont-Moreno, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, P. Colín-Farias, U. Cotti, J. Cotzomi, S. Coutiño de León, E. De la Fuente, C. de León, D. Depaoli, R. Diaz Hernandez, J. C. Díaz-Vélez, M. Durocher, M. A. DuVernois, K. Engel, C. Espinoza, K. L. Fan, N. Fraija, J. A. García-González, F. Garfias, A. Gonzalez Muñoz, M. M. González, J. A. Goodman, J. P. Harding, D. Huang, F. Hueyotl-Zahuantitla, A. Iriarte, S. Kaufmann, A. Lara, J. Lee, H. León Vargas, A. L. Longinotti, G. Luis-Raya, K. Malone, O. Martinez, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, T. Niembro, R. Noriega-Papaqui, N. Omodei, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, E. Ruiz-Velasco, J. Ryan, H. Salazar, D. Salazar-Gallegos, A. Sandoval, J. Serna-Franco, A. J. Smith, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Turner, F. Ureña-Mena, E. Varela, L. Villaseñor, X. Wang, I. J. Watson, E. Willox, S. Yun-Cárcamo, and H. Zhou

Subjects
Active solar corona, Solar magnetic fields, Solar physics, Astrophysics, QB460-466
Abstract

Galactic cosmic rays (GCRs) are charged particles that reach the heliosphere almost isotropically in a wide energy range. In the inner heliosphere, the GCR flux is modulated by solar activity so that only energetic GCRs reach the lower layers of the solar atmosphere. In this work, we propose that high-energy GCRs can be used to explore the solar magnetic fields at low coronal altitudes. We used GCR data collected by the High-Altitude Water Cherenkov observatory to construct maps of GCR flux coming from the Sun’s sky direction and studied the observed GCR deficit, known as Sun shadow (SS), over a 6 yr period (2016–2021) with a time cadence of 27.3 days. We confirm that the SS is correlated with sunspot number, but we focus on the relationship between the photospheric solar magnetic field measured at different heliolatitudes and the relative GCR deficit at different energies. We found a linear relationship between the relative deficit of GCRs represented by the depth of the SS and the solar magnetic field. This relationship is evident in the observed energy range of 2.5–226 TeV, but is strongest in the range of 12.4 33.4 TeV, which implies that this is the best energy range to study the evolution of magnetic fields in the low solar atmosphere.

Published
2024
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7. Galactic Gamma-Ray Diffuse Emission at TeV Energies with HAWC Data

Author

R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez, K. P. Arunbabu, D. Avila Rojas, R. Babu, V. Baghmanyan, E. Belmont-Moreno, C. Brisbois, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, O. Chaparro-Amaro, U. Cotti, J. Cotzomi, S. Coutiño de León, E. De la Fuente, R. Diaz Hernandez, M. A. DuVernois, M. Durocher, J. C. Díaz-Vélez, K. Engel, C. Espinoza, K. L. Fan, N. Fraija, A. Galván-Gámez, J. A. García-González, F. Garfias, M. M. González, J. A. Goodman, S. Hernandez, B. Hona, D. Huang, F. Hueyotl-Zahuantitla, T. B. Humensky, A. Iriarte, V. Joshi, S. Kaufmann, D. Kieda, G. J. Kunde, A. Lara, H. León Vargas, J. T. Linnemann, A. L. Longinotti, G. Luis-Raya, K. Malone, O. Martinez, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, R. Noriega-Papaqui, E. G. Pérez-Pérez, D. Rosa-González, E. Ruiz-Velasco, H. Salazar, D. Salazar-Gallegos, F. Salesa Greus, A. Sandoval, J. Serna-Franco, A. J. Smith, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, F. Ureña-Mena, L. Villaseñor, E. Willox, H. Zhou, C. de León, O. Fornieri, D. Gaggero, D. Grasso, A. Marinelli, S. Ventura, and HAWC Collaboration

Subjects
Gamma-ray astronomy, High energy astrophysics, Galactic cosmic rays, Milky Way disk, Astrophysics, QB460-466
Abstract

Galactic gamma-ray diffuse emission (GDE) is emitted by cosmic rays (CRs), ultra-relativistic protons, and electrons, interacting with gas and electromagnetic radiation fields in the interstellar medium. Here we present the analysis of teraelectronvolt diffuse emission from a region of the Galactic plane over the range in longitude of l ∈ [43°, 73°], using data collected with the High Altitude Water Cherenkov (HAWC) detector. Spectral, longitudinal, and latitudinal distributions of the teraelectronvolt diffuse emission are shown. The radiation spectrum is compatible with the spectrum of the emission arising from a CR population with an index similar to that of the observed CRs. When comparing with the DRAGON base model , the HAWC GDE flux is higher by about a factor of 2. Unresolved sources such as pulsar wind nebulae and teraelectronvolt halos could explain the excess emission. Finally, deviations of the Galactic CR flux from the locally measured CR flux may additionally explain the difference between the predicted and measured diffuse fluxes.

Published
2024
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8. HAWC Detection of a TeV Halo Candidate Surrounding a Radio-quiet Pulsar

Author

A. Albert, R. Alfaro, J. C. Arteaga-Velázquez, H. A. Ayala Solares, E. Belmont-Moreno, T. Capistrán, A. Carramiñana, S. Casanova, J. Cotzomi, S. Coutiño De León, E. De la Fuente, C. de León, R. Diaz Hernandez, M. A. DuVernois, J. C. Díaz-Vélez, C. Espinoza, K. L. Fan, N. Fraija, K. Fang, J. A. García-González, F. Garfias, A. Jardin-Blicq, M. M. González, J. A. Goodman, J. P. Harding, S. Hernandez, D. Huang, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, V. Joshi, A. Lara, J. Lee, H. León Vargas, J. T. Linnemann, A. L. Longinotti, G. Luis-Raya, K. Malone, O. Martinez, J. Martínez-Castro, J. A. Matthews, J. A. Morales-Soto, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, M. Newbold, M. U. Nisa, Y. Pérez Araujo, Y. Son, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, A. Sandoval, M. Schneider, J. Serna-Franco, A. J. Smith, R. W. Springer, K. Tollefson, I. Torres, R. Torres-Escobedo, X. Wang, K. Whitaker, E. Willox, H. Zhou, and THE HAWC COLLABORATION

Subjects
Pulsars, Gamma-ray astronomy, High energy astrophysics, Astrophysics, QB460-466
Abstract

Extended very-high-energy (VHE; 0.1–100 TeV) γ -ray emission has been observed around several middle-aged pulsars and referred to as “TeV halos.” Their formation mechanism remains under debate. It is also unknown whether they are ubiquitous or related to a certain subgroup of pulsars. With 2321 days of observation, the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory detected VHE γ -ray emission at the location of the radio-quiet pulsar PSR J0359+5414 with >6 σ significance. By performing likelihood tests with different spectral and spatial models and comparing the TeV spectrum with multiwavelength observations of nearby sources, we show that this excess is consistent with a TeV halo associated with PSR J0359+5414, though future observation of HAWC and multiwavelength follow-ups are needed to confirm this nature. This new halo candidate is located in a noncrowded region in the outer galaxy. It shares similar properties to the other halos but its pulsar is younger and radio-quiet. Our observation implies that TeV halos could commonly exist around pulsars and their formation does not depend on the configuration of the pulsar magnetosphere.

Published
2023
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9. HAWC Study of the Very-high-energy γ-Ray Spectrum of HAWC J1844−034

Author

A. Albert, C. Alvarez, D. Avila Rojas, H. A. Ayala Solares, R. Babu, E. Belmont-Moreno, M. Breuhaus, T. Capistrán, A. Carramiñana, S. Casanova, J. Cotzomi, S. Coutiño de León, E. De la Fuente, D. Depaoli, R. Diaz Hernandez, B. L. Dingus, M. A. DuVernois, M. Durocher, K. Engel, C. Espinoza, K. L. Fan, K. Fang, N. Fraija, J. A. García-González, M. M. González, J. A. Goodman, S. Groetsch, J. P. Harding, I. Herzog, J. Hinton, D. Huang, F. Hueyotl-Zahuantitla, T. B. Humensky, P. Hüntemeyer, V. Joshi, S. Kaufmann, J. Lee, H. León Vargas, A. L. Longinotti, G. Luis-Raya, K. Malone, O. Martinez, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, J. A. Morales-Soto, E. Moreno, M. Mostafá, L. Nellen, R. Noriega-Papaqui, L. Olivera-Nieto, N. Omodei, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, E. Ruiz-Velasco, H. Salazar, D. Salazar-Gallegos, A. Sandoval, M. Schneider, J. Serna-Franco, A. J. Smith, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Ureña-Mena, E. Varela, L. Villaseñor, X. Wang, I. J. Watson, E. Willox, H. Zhou, and HAWC collaboration

Subjects
γ-ray sources, Pulsars, Supernova remnants, Astrophysics, QB460-466
Abstract

Recently, the region surrounding eHWC J1842−035 has been studied extensively by γ-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 1910 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 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 γ-ray sources with a matching origin. Also, we present and use the multiwavelength data to fit the hadronic and leptonic particle spectra. We have identified four pulsar candidates in the nearby region in 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.

Published
2023
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10. Search for Gamma-Ray and Neutrino Coincidences Using HAWC and ANTARES Data

Author

H. A. Ayala Solares, S. Coutu, D. Cowen, D. B. Fox, T. Grégoire, F. McBride, M. Mostafá, K. Murase, S. Wissel, AMON Team, A. Albert, S. Alves, M. André, M. Ardid, S. Ardid, J.-J. Aubert, J. Aublin, B. Baret, S. Basa, B. Belhorma, M. Bendahman, F. Benfenati, V. Bertin, S. Biagi, M. Bissinger, J. Boumaaza, M. Bouta, M. C. Bouwhuis, H. Brânzaş, R. Bruijn, J. Brunner, J. Busto, B. Caiffi, D. Calvo, A. Capone, L. Caramete, J. Carr, V. Carretero, S. Celli, M. Chabab, T. N. Chau, R. Cherkaoui El Moursli, T. Chiarusi, M. Circella, J. A. B. Coelho, A. Coleiro, R. Coniglione, P. Coyle, A. Creusot, A. F. Díaz, G. de Wasseige, B. De Martino, C. Distefano, I. Di Palma, A. Domi, C. Donzaud, D. Dornic, D. Drouhin, T. Eberl, T. van Eeden, D. van Eijk, N. El Khayati, A. Enzenhöfer, P. Fermani, G. Ferrara, F. Filippini, L. Fusco, J. García, P. Gay, H. Glotin, R. Gozzini, R. Gracia Ruiz, K. Graf, C. Guidi, S. Hallmann, H. van Haren, A. J. Heijboer, Y. Hello, J. J. Hernández-Rey, J. Hößl, J. Hofestädt, F. Huang, G. Illuminati, C. W. James, B. Jisse-Jung, M. de Jong, P. de Jong, M. Kadler, O. Kalekin, U. Katz, A. Kouchner, I. Kreykenbohm, V. Kulikovskiy, R. Lahmann, M. Lamoureux, R. Le Breton, D. Lefèvre, E. Leonora, G. Levi, S. Le Stum, D. Lopez-Coto, S. Loucatos, L. Maderer, J. Manczak, M. Marcelin, A. Margiotta, A. Marinelli, J. A. Martínez-Mora, K. Melis, P. Migliozzi, A. Moussa, R. Muller, L. Nauta, S. Navas, E. Nezri, B. Ó Fearraigh, A. Păun, G. E. Păvălaş, C. Pellegrino, M. Perrin-Terrin, V. Pestel, P. Piattelli, C. Pieterse, C. Poirè, V. Popa, T. Pradier, N. Randazzo, D. Real, S. Reck, G. Riccobene, A. Romanov, A. Sánchez-Losa, D. F. E. Samtleben, M. Sanguineti, P. Sapienza, J. Schnabel, J. Schumann, F. Schüssler, J. Seneca, M. Spurio, Th. Stolarczyk, M. Taiuti, Y. Tayalati, S. J. Tingay, B. Vallage, V. Van Elewyck, F. Versari, S. Viola, D. Vivolo, J. Wilms, S. Zavatarelli, A. Zegarelli, J. D. Zornoza, J. Zúñiga, ANTARES Collaboration, C. Alvarez, J. C. Arteaga-Velázquez, R. Babu, E. Belmont-Moreno, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, U. Cotti, O. Chaparro-Amaro, J. Cotzomi, S. Coutiño de León, E. De la Fuente, C. de León, R. Diaz Hernandez, M. A. DuVernois, M. Durocher, J. C. Díaz-Vélez, K. Engel, C. Espinoza, K. L. Fan, M. Fernández Alonso, N. Fraija, J. A. García-González, F. Garfias, M. M. González, J. A. Goodman, J. P. Harding, S. Hernandez, D. Huang, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, V. Joshi, S. Kaufmann, A. Lara, H. León Vargas, J. T. Linnemann, A. L. Longinotti, G. Luis-Raya, K. Malone, O. Martinez, I. Martinez-Castellanos, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, J. A. Morales-Soto, E. Moreno, A. Nayerhoda, L. Nellen, M. U. Nisa, R. Noriega-Papaqui, N. Omodei, A. Peisker, Y. Pérez Araujo, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, E. Ruiz-Velasco, H. Salazar, F. Salesa Greus, A. Sandoval, M. Schneider, A. J. Smith, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Ureña-Mena, E. Varela, X. Wang, K. Whitaker, E. Willox, A. Zepeda, H. Zhou, and HAWC Collaboration

Subjects
High energy astrophysics, Astrophysics, QB460-466
Abstract

In the quest for high-energy neutrino sources, the Astrophysical Multimessenger Observatory Network has implemented a new search by combining data from the High Altitude Water Cherenkov (HAWC) Observatory and the Astronomy with a Neutrino Telescope and Abyss environmental RESearch (ANTARES) neutrino telescope. Using the same analysis strategy as in a previous detector combination of HAWC and IceCube data, we perform a search for coincidences in HAWC and ANTARES events that are below the threshold for sending public alerts in each individual detector. Data were collected between 2015 July and 2020 February with a live time of 4.39 yr. Over this time period, three coincident events with an estimated false-alarm rate of

Published
2023
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11. Searching for TeV Dark Matter in Irregular Dwarf Galaxies with HAWC Observatory

Author

R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A. Ayala Solares, R. Babu, E. Belmont-Moreno, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, O. Chaparro-Amaro, U. Cotti, J. Cotzomi, E. De la Fuente, R. Diaz Hernandez, B. L. Dingus, M. A. DuVernois, M. Durocher, J. C. Díaz-Vélez, C. Espinoza, K. L. Fan, N. Fraija, J. A. García-González, F. Garfias, M. M. González, J. P. Harding, S. Hernández-Cadena, D. Huang, F. Hueyotl-Zahuantitla, A. Iriarte, V. Joshi, S. Kaufmann, D. Kieda, J. Lee, H. León Vargas, J. T. Linnemann, A. L. Longinotti, G. Luis-Raya, K. Malone, O. Martinez, J. Martínez-Castro, J. A. Matthews, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, N. Omodei, Y. Pérez Araujo, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, H. Salazar, D. Salazar-Gallegos, A. Sandoval, J. Serna-Franco, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Ureña-Mena, L. Villaseñor, X. Wang, E. Willox, H. Zhou, C. de León, The HAWC Collaboration, V. Gammaldi, E. Karukes, and P. Salucci

Subjects
Dark matter, Cold dark matter, Galaxies, Dwarf irregular galaxies, Particle astrophysics, Gamma-rays, Astrophysics, QB460-466
Abstract

We present the results of dark matter (DM) searches in a sample of 31 dwarf irregular (dIrr) galaxies within the field of view of the HAWC Observatory. dIrr galaxies are DM-dominated objects in which astrophysical gamma-ray emission is estimated to be negligible with respect to the secondary gamma-ray flux expected by annihilation or decay of weakly interacting massive particles (WIMPs). While we do not see any statistically significant DM signal in dIrr galaxies, we present the exclusion limits (95% C.L.) for annihilation cross section and decay lifetime for WIMP candidates with masses between 1 and 100 TeV. Exclusion limits from dIrr galaxies are relevant and complementary to benchmark dwarf Spheroidal (dSph) galaxies. In fact, dIrr galaxies are targets kinematically different from benchmark dSph, preserving the footprints of different evolution histories. We compare the limits from dIrr galaxies to those from ultrafaint and classical dSph galaxies previously observed with HAWC. We find that the constraints are comparable to the limits from classical dSph galaxies and ∼2 orders of magnitude weaker than the ultrafaint dSph limits.

Published
2023
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12. Detailed Analysis of the TeV γ-Ray Sources 3HWC J1928+178, 3HWC J1930+188, and the New Source HAWC J1932+192

Author

A. Albert, R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A. Ayala Solares, R. Babu, E. Belmont-Moreno, C. Brisbois, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, O. Chaparro-Amaro, U. Cotti, J. Cotzomi, S. Coutiño de León, E. De la Fuente, C. de León, R. Diaz Hernandez, J. C. Díaz-Vélez, B. L. Dingus, M. A. DuVernois, M. Durocher, K. Engel, C. Espinoza, K. L. Fan, M. Fernández Alonso, N. Fraija, J. A. García-González, F. Garfias, H. Goksu, M. M. González, J. A. Goodman, J. P. Harding, S. Hernandez, J. Hinton, B. Hona, D. Huang, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, A. Jardin-Blicq, V. Joshi, S. Kaufmann, D. Kieda, W. H. Lee, H. León Vargas, J. T. Linnemann, A. L. Longinotti, G. Luis-Raya, R. López-Coto, K. Malone, V. Marandon, O. Martinez, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, J. A. Morales-Soto, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, M. Newbold, M. U. Nisa, R. Noriega-Papaqui, L. Olivera-Nieto, N. Omodei, A. Peisker, Y. Pérez Araujo, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, E. Ruiz-Velasco, H. Salazar, D. Salazar-Gallegos, F. Salesa Greus, A. Sandoval, M. Schneider, J. Serna-Franco, A. J. Smith, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Ureña-Mena, L. Villaseñor, X. Wang, F. Werner, E. Willox, H. Zhou, and HAWC collaboration

Subjects
High energy astrophysics, Gamma-ray astronomy, Pulsars, Pulsar wind nebulae, Non-thermal radiation sources, Astrophysics, QB460-466
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° < ℓ < 55°, 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 γ -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 an attempt to unveil the origins of the very-high-energy γ -ray emission.

Published
2023
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13. HAWC Study of the Ultra-high-energy Spectrum of MGRO J1908+06

Author

A. Albert, R. Alfaro, C. Alvarez, J. D. Álvarez, J. R. Angeles Camacho, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A. Ayala Solares, R. Babu, E. Belmont-Moreno, C. Brisbois, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, U. Cotti, J. Cotzomi, S. Coutiño de León, E. De la Fuente, C. de León, R. Diaz Hernandez, B. L. Dingus, M. A. DuVernois, M. Durocher, J. C. Díaz-Vélez, K. Engel, C. Espinoza, K. L. Fan, K. Fang, M. Fernández Alonso, N. Fraija, D. Garcia, J. A. García-González, F. Garfias, G. Giacinti, H. Goksu, M. M. González, J. A. Goodman, J. P. Harding, J. Hinton, B. Hona, D. Huang, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, A. Jardin-Blicq, V. Joshi, S. Kaufmann, D. Kieda, W. H. Lee, J. Lee, H. León Vargas, J. T. Linnemann, A. L. Longinotti, G. Luis-Raya, K. Malone, V. Marandon, O. Martinez, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, J. A. Morales-Soto, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, M. Newbold, M. U. Nisa, R. Noriega-Papaqui, L. Olivera-Nieto, N. Omodei, A. Peisker, Y. Pérez Araujo, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, H. Salazar, F. Salesa Greus, A. Sandoval, M. Schneider, H. Schoorlemmer, J. Serna-Franco, A. J. Smith, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Ureña-Mena, L. Villaseñor, X. Wang, I. J. Watson, E. Willox, A. Zepeda, H. Zhou, M. Breuhaus, H. Li, and H. Zhang

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, ddc:530, High Energy Physics, 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
2022
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14. The High-Altitude Water Cherenkov (HAWC) Observatory in México: The Primary Detector

Author

A.U. Abeysekara, A. Albert, R. Alfaro, C. Alvarez, J.D. Álvarez, M. Araya, J.C. Arteaga-Velázquez, K.P. Arunbabu, D. Avila Rojas, H.A. Ayala Solares, R. Babu, A.S. Barber, A. Becerril, E. Belmont-Moreno, S.Y. BenZvi, O. Blanco, J. Braun, C. Brisbois, K.S. Caballero-Mora, J.I. Cabrera Martínez, T. Capistrán, A. Carramiñana, S. Casanova, M. Castillo, O. Chaparro-Amaro, U. Cotti, J. Cotzomi, S. Coutiño de León, E. de la Fuente, C. de León, T. De Young, R. Diaz Hernandez, B.L. Dingus, M.A. DuVernois, M. Durocher, J.C. Díaz-Vélez, R.W. Ellsworth, K. Engel, C. Espinoza, K.L. Fan, K. Fang, B. Fick, H. Fleischhack, J.L. Flores, N. Fraija, J.A. García-González, G. Garcia-Torales, F. Garfias, G. Giacinti, H. Goksu, M.M. González, A. González-Muñoz, J.A. Goodman, J.P. Harding, E. Hernandez, S. Hernandez, J. Hinton, B. Hona, D. Huang, F. Hueyotl-Zahuantitla, C.M. Hui, T.B. Humensky, P. Hüntemeyer, A. Iriarte, A. Imran, A. Jardin-Blicq, V. Joshi, S. Kaufmann, D. Kieda, G.J. Kunde, A. Lara, R. Lauer, W.H. Lee, D. Lennarz, H. León Vargas, J.T. Linnemann, A.L. Longinotti, G. Luis-Raya, J. Lundeen, K. Malone, V. Marandon, A. Marinelli, O. Martinez, I. Martínez-Castellanos, J. Martínez-Castro, H. Martínez-Huerta, J.A. Matthews, P. Miranda-Romagnoli, T. Montaruli, J.A. Morales-Soto, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, M. Newbold, M.U. Nisa, R. Noriega-Papaqui, T. Oceguera-Becerra, L. Olivera-Nieto, N. Omodei, A. Peisker, Y. Pérez Araujo, E.G. Pérez-Pérez, E. Ponce, J. Pretz, C.D. Rho, D. Rosa-González, E. Ruiz-Velasco, H. Salazar, D. Salazar-Gallegos, F. Salesa Greus, A. Sandoval, M. Schneider, H. Schoorlemmer, J. Serna-Franco, G. Sinnis, A.J. Smith, Y. Son, K. Sparks Woodle, R.W. Springer, I. Taboada, A. Tepe, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Ureña-Mena, T.N. Ukwatta, E. Varela, M. Vargas-Magaña, L. Villaseñor, X. Wang, I.J. Watson, F. Werner, S. Westerhoff, E. Willox, I. Wisher, J. Wood, G.B. Yodh, D. Zaborov, A. Zepeda, and H. Zhou

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Nuclear and High Energy Physics, FOS: Physical sciences, High Energy Physics, Molecular Developmental Biology, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation, Instrumentation and Methods for Astrophysics (astro-ph.IM)
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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15. Study of the Very High Energy Emission of M87 through its Broadband Spectral Energy Distribution

Author

R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A. Ayala Solares, E. Belmont-Moreno, T. Capistrán, A. Carramiñana, S. Casanova, U. Cotti, J. Cotzomi, S. Coutiño de León, E. De la Fuente, C. de León, R. Diaz Hernandez, M. A. DuVernois, M. Durocher, J. C. Díaz-Vélez, C. Espinoza, K. L. Fan, M. Fernández Alonso, N. Fraija, J. A. García-González, F. Garfias, M. M. González, J. A. Goodman, J. P. Harding, D. Huang, F. Hueyotl-Zahuantitla, P. Hüntemeyer, V. Joshi, H. León Vargas, J. T. Linnemann, A. L. Longinotti, G. Luis-Raya, K. Malone, O. Martinez, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, R. Noriega-Papaqui, N. Omodei, A. Peisker, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, H. Salazar, D. Salazar-Gallegos, F. Salesa Greus, A. Sandoval, J. Serna-Franco, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, F. Ureña-Mena, L. Villaseñor, X. Wang, E. Willox, and A. Zepeda

Subjects
Space and Planetary Science, Astronomy and Astrophysics, ddc:530
Abstract

The radio galaxy M87 is the central dominant galaxy of the Virgo Cluster. Very high-energy (VHE, ≳0.1 TeV) emission from M87 has been detected by imaging air Cherenkov telescopes. Recently, marginal evidence for VHE long-term emission has also been observed by the High Altitude Water Cherenkov Observatory, a gamma-ray and cosmic-ray detector array located in Puebla, Mexico. The mechanism that produces VHE emission in M87 remains unclear. This emission originates in its prominent jet, which has been spatially resolved from radio to X-rays. In this paper, we construct a spectral energy distribution from radio to gamma rays that is representative of the nonflaring activity of the source, and in order to explain the observed emission, we fit it with a lepto-hadronic emission model. We found that this model is able to explain nonflaring VHE emission of M87 as well as an orphan flare reported in 2005.

Published
2022

16. Gamma/Hadron Separation with the HAWC Observatory

Author

R. Alfaro, C. Alvarez, J.D. Álvarez, J.R. Angeles Camacho, J.C. Arteaga-Velázquez, D. Avila Rojas, H.A. Ayala Solares, R. Babu, E. Belmont-Moreno, C. Brisbois, K.S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, O. Chaparro-Amaro, U. Cotti, J. Cotzomi, S. Coutiño de León, E. De la Fuente, C. de León, R. Diaz Hernandez, B.L. Dingus, M.A. DuVernois, M. Durocher, J.C. Díaz-Vélez, R.W. Ellsworth, K. Engel, C. Espinoza, K.L. Fan, M. Fernández Alonso, N. Fraija, D. Garcia, J.A. García-González, F. Garfias, M.M. González, J.A. Goodman, J.P. Harding, S. Hernandez, B. Hona, D. Huang, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, A. Jardin-Blicq, V. Joshi, S. Kaufmann, G.J. Kunde, A. Lara, W.H. Lee, J. Lee, H. León Vargas, J.T. Linnemann, G. Luis-Raya, J. Lundeen, K. Malone, V. Marandon, O. Martinez, J. Martínez-Castro, J.A. Matthews, P. Miranda-Romagnoli, J.A. Morales-Soto, A. Nayerhoda, L. Nellen, M.U. Nisa, R. Noriega-Papaqui, L. Olivera-Nieto, N. Omodei, A. Peisker, Y. Pérez Araujo, E.G. Pérez-Pérez, C.D. Rho, D. Rosa-González, E. Ruiz-Velasco, H. Salazar, F. Salesa Greus, A. Sandoval, P.M. Saz Parkinson, J. Serna-Franco, A.J. Smith, R.W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Ureña-Mena, L. Villaseñor, X. Wang, I.J. Watson, F. Werner, E. Willox, J. Wood, A. Zepeda, and H. Zhou

Subjects
HAWC - Abteilung Hinton, High Energy Astrophysical Phenomena (astro-ph.HE), Nuclear and High Energy Physics, Physics - Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Instrumentation
Abstract

The High Altitude Water Cherenkov (HAWC) gamma-ray observatory observes atmospheric showers produced by incident gamma rays and cosmic rays with energy from 300 GeV to more than 100 TeV. A crucial phase in analyzing gamma-ray sources using ground-based gamma-ray detectors like HAWC is to identify the showers produced by gamma rays or hadrons. The HAWC observatory records roughly 25,000 events per second, with hadrons representing the vast majority ($>99.9\%$) of these events. The standard gamma/hadron separation technique in HAWC uses a simple rectangular cut involving only two parameters. This work describes the implementation of more sophisticated gamma/hadron separation techniques, via machine learning methods (boosted decision trees and neural networks), and summarizes the resulting improvements in gamma/hadron separation obtained in HAWC., 35 pages, 9 figures, published in Nuclear Instruments and Methods in Physics Research Section A

Published
2022

17. Probing the extragalactic mid-infrared background with HAWC

Author

A. Albert, R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A. Ayala Solares, R. Babu, E. Belmont-Moreno, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, O. Chaparro-Amaro, U. Cotti, J. Cotzomi, S. Coutiño de León, E. De la Fuente, R. Diaz Hernandez, M. A. DuVernois, M. Durocher, J. C. Díaz-Vélez, K. Engel, C. Espinoza, K. L. Fan, M. Fernández Alonso, N. Fraija, J. A. García-González, F. Garfias, M. M. González, J. A. Goodman, J. P. Harding, S. Hernandez, D. Huang, F. Hueyotl-Zahuantitla, P. Hntemeyer, A. Iriarte, A. Jardin-Blicq, V. Joshi, D. Kieda, W. H. Lee, J. T. Linnemann, A. L. Longinotti, G. Luis-Raya, K. Malone, O. Martinez, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, M. Newbold, M. U. Nisa, R. Noriega-Papaqui, N. Omodei, A. Peisker, Y. Pérez Araujo, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, H. Salazar, D. Salazar-Gallegos, F. Salesa Greus, A. Sandoval, J. Serna-Franco, A. J. Smith, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Ureña-Mena, L. Villaseñor, X. Wang, T. Weisgarber, E. Willox, H. Zhou, and C. de León

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, ddc:520, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics
Abstract

The extragalactic background light (EBL) contains all the radiation emitted by nuclear and accretion processes in stars and compact objects since the epoch of recombination. Measuring the EBL density directly is challenging, especially in the near- to far-infrared waveband, mainly due to the zodiacal light foreground. Instead, gamma-ray astronomy offers the possibility to indirectly set limits on the EBL by studying the effects of gamma-ray absorption in the very high energy (VHE:$>$100 GeV) spectra of distant blazars. The High Altitude Water Cherenkov gamma ray observatory (HAWC) is one of the few instruments sensitive to gamma rays with energies above 10 TeV. This offers the opportunity to probe the EBL in the near/mid IR region: $\lambda$ = 1 $\mu$m - 100 $\mu$m. In this study, we fit physically motivated emission models to Fermi Large Area Telescope (LAT) GeV data to extrapolate the intrinsic TeV spectra of blazars. We then simulate a large number of absorbed spectra for different randomly generated EBL model shapes and calculate Bayesian credible bands in the EBL intensity space by comparing and testing the agreement between the absorbed spectra and HAWC extragalactic observations of two blazars. The resulting bands are in agreement with current EBL lower and upper limits, showing a downward trend towards higher wavelength values $\lambda>10\, \mu$m also observed in previous measurements., Comment: Submitted to ApJ

Published
2022
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18. Long-term spectra of the blazars Mrk 421 and Mrk 501 at TeV energies seen by HAWC

Author

A. Albert, R. Alfaro, C. Alvarez, J. R. Angeles Camacho, J. C. Arteaga-Velázquez, K. P. Arunbabu, D. Avila Rojas, H. A. Ayala Solares, V. Baghmanyan, E. Belmont-Moreno, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, U. Cotti, J. Cotzomi, S. Coutiño de León, E. De la Fuente, R. Diaz Hernandez, M. A. DuVernois, M. Durocher, J. C. Díaz-Vélez, K. Engel, C. Espinoza, K. L. Fan, M. Fernández Alonso, N. Fraija, D. Garcia, J. A. García-González, F. Garfias, M. M. González, J. A. Goodman, J. P. Harding, B. Hona, D. Huang, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, V. Joshi, A. Lara, W. H. Lee, J. Lee, H. León Vargas, J. T. Linneman, A. L. Longinotti, G. Luis-Raya, K. Malone, O. Martinez, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, M. Newbold, R. Noriega-Papaqui, A. Peisker, Y. Pérez Araujo, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, H. Salazar, F. Salesa Greus, A. Sandoval, M. Schneider, J. Serna-Franco, A. J. Smith, R. W. Springer, K. Tollefson, I. Torres, R. Torres-Escobedo, F. Ureña-Mena, L. Villaseñor, X. Wang, T. Weisgarber, E. Willox, H. Zhou, and C. de León

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, ddc:530, High Energy Physics::Experiment, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

The High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory surveys the very high energy sky in the 300 GeV to $>100$ TeV energy range. HAWC has detected two blazars above $11\sigma$, Markarian 421 (Mrk 421) and Markarian 501 (Mrk 501). The observations are comprised of data taken in the period between June 2015 and July 2018, resulting in a $\sim 1038$ days of exposure. In this work we report the time-averaged spectral analysis for both sources above 0.5 TeV. Taking into account the flux attenuation due to the extragalactic background light (EBL), the intrinsic spectrum of Mrk 421 is described by a power law with an exponential energy cut-off with index $\alpha=2.26\pm(0.12)_{stat}(_{-0.2}^{+0.17})_{sys}$ and energy cut-off $E_c=5.1\pm(1.6)_{stat}(_{-2.5}^{+1.4})_{sys}$ TeV, while the intrinsic spectrum of Mrk 501 is better described by a simple power law with index $\alpha=2.61\pm(0.11)_{stat}(_{-0.07}^{+0.01})_{sys}$. The maximum energies at which the Mrk 421 and Mrk 501 signals are detected are 9 and 12 TeV, respectively. This makes these some of the highest energy detections to date for spectra averaged over years-long timescales. Since the observation of gamma radiation from blazars provides information about the physical processes that take place in their relativistic jets, it is important to study the broad-band spectral energy distribution (SED) of these objects. To this purpose, contemporaneous data in the gamma-ray band to X-ray range, and literature data in the radio to UV range, were used to build time-averaged SEDs that were modeled within a synchrotron self-Compton leptonic scenario., Comment: 16 pages, 5 tables, 9 figures

Published
2021
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19. Evidence of 200 TeV photons from HAWC J1825-134

Author

R. Noriega-Papaqui, J. R. Angeles Camacho, Gerd J. Kunde, Luis Villaseñor, C. Brisbois, K. Tollefson, J. T. Linnemann, Catalina Espinoza, D. Garcia, F. Serna, Nicola Omodei, A. Iriarte, H. A. Ayala Solares, Lukas Nellen, I. Torres, E. Belmont-Moreno, Gwenael Giacinti, A. Sandoval, B. Hona, Segev BenZvi, J. C. Díaz-Vélez, Vincent Marandon, H. Fleischhack, Michael Schneider, J. Lundeen, Mehr Nisa, K. Engel, Vardan Baghmanyan, F. Salesa Greus, Nissim Fraija, K. P. Arunbabu, A. L. Longinotti, M. Mostafá, J. A. Goodman, M. Durocher, A. Jardin-Blicq, C. De León, Andrea Albert, M. Newbold, U. Cotti, Brenda Dingus, J. P. Harding, J. Martínez-Castro, Alejandro Lara, A. Peisker, E. Moreno, Amid Nayerhoda, Daniel Rosa-Gonzalez, Michael DuVernois, A. Carramiñana, Y. Pérez Araujo, H. León Vargas, R. Diaz Hernandez, E. Willox, P. Miranda-Romagnoli, John Matthews, A. Galván-Gámez, E. De la Fuente, D. Avila Rojas, Oscar Martinez, G. Luis-Raya, Sabrina Casanova, V. Joshi, J.C. Arteaga-Velázquez, P. Hüntemeyer, W. H. Lee, Ke Fang, R. Torres-Escobedo, T. Capistrán, J. Cotzomi, F. Ureña-Mena, F. Garfias, Maria Magdalena González, Hongyan Zhou, Filiberto Hueyotl-Zahuantitla, Ruben Alfaro, C. D. Rho, R. W. Springer, H. Salazar, C. Alvarez, D. Huang, K. Malone, E. G. Pérez-Pérez, and Jose Andres Garcia-Gonzalez

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Photon, 010504 meteorology & atmospheric sciences, Proton, Molecular cloud, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Cosmic ray, Astrophysics, Radiation, 7. Clean energy, 01 natural sciences, Galaxy, 13. Climate action, Space and Planetary Science, Observatory, 0103 physical sciences, Physics::Accelerator Physics, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Cherenkov radiation, 0105 earth and related environmental sciences
Abstract

The Earth is bombarded by ultra-relativistic particles, known as cosmic rays (CRs). CRs with energies up to a few PeV (=10$^{15}$ eV), the knee in the particle spectrum, are believed to have a Galactic origin. One or more factories of PeV CRs, or PeVatrons, must thus be active within our Galaxy. The direct detection of PeV protons from their sources is not possible since they are deflected in the Galactic magnetic fields. Hundred TeV $\gamma$-rays from decaying $\pi^0$, produced when PeV CRs collide with the ambient gas, can provide the decisive evidence of proton acceleration up to the knee. Here we report the discovery by the High Altitude Water Cherenkov (HAWC) observatory of the $\gamma$-ray source, HAWC~J1825-134, whose energy spectrum extends well beyond 200 TeV without a break or cutoff. The source is found to be coincident with a giant molecular cloud. The ambient gas density is as high as 700 protons/cm$^3$. While the nature of this extreme accelerator remains unclear, CRs accelerated to energies of several PeV colliding with the ambient gas likely produce the observed radiation., Comment: Accepted for publication in ApJL

Published
2020

20. Analysis of Multimolecular Enzymes as an Aid to the Identification of Certain Rapidly Growing Mycobacteria, using Starch Gel Electrophoresis

Author

Margaret E. Willox and D. C. Cann

Subjects
chemistry.chemical_classification, biology, Starch, General Medicine, bacterial infections and mycoses, biology.organism_classification, Applied Microbiology and Biotechnology, Microbiology, Esterase, Electrophoresis, chemistry.chemical_compound, Starch gel electrophoresis, Enzyme, chemistry, Biochemistry, Catalase, biology.protein, Identification (biology), Mycobacterium phlei, Biotechnology
Abstract

Four species of rapidly growing mycobacteria were shown to have multi-molecular forms of esterase and catalase. The number and positions of bands of esterases after electrophoresis in starch gel were characteristic for each of the species Mycobacterium phlei, M. smegmatis, M. fortuitum and M. rhodochrous. Strains of these species are readily identified within 4 days by the method. M. smegmatis and M. fortuitum had esterases which were still active after heating at 100° for 10 min.

Published
1965
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21. Ultra-high-energy gamma-ray bubble around microquasar V4641 Sgr.

Author

Alfaro R, Alvarez C, Arteaga-Velázquez JC, Avila Rojas D, Ayala Solares HA, Babu R, Belmont-Moreno E, Caballero-Mora KS, Capistrán T, Carramiñana A, Casanova S, Cotti U, Cotzomi J, Coutiño de León S, De la Fuente E, Depaoli D, Di Lalla N, Diaz Hernandez R, Dingus BL, DuVernois MA, Durocher M, Díaz-Vélez JC, Engel K, Espinoza C, Fan KL, Fang K, Fraija N, Fraija S, García-González JA, Garfias F, Gonzalez Muñoz A, González MM, Goodman JA, Groetsch S, Harding JP, Herzog I, Hinton J, Huang D, Hueyotl-Zahuantitla F, Hüntemeyer P, Iriarte A, Joshi V, Kaufmann S, Kieda D, de León C, Lee J, León Vargas H, Linnemann JT, Longinotti AL, Luis-Raya G, Malone K, Martinez O, Martínez-Castro J, Matthews JA, Miranda-Romagnoli P, Morales-Soto JA, Moreno E, Mostafá M, Nayerhoda A, Nellen L, Newbold M, Nisa MU, Noriega-Papaqui R, Olivera-Nieto L, Omodei N, Osorio M, Pérez Araujo Y, Pérez-Pérez EG, Rho CD, Rosa-González D, Ruiz-Velasco E, Salazar H, Salazar-Gallegos D, Sandoval A, Schneider M, Serna-Franco J, Smith AJ, Son Y, Springer RW, Tibolla O, Tollefson K, Torres I, Torres-Escobedo R, Turner R, Ureña-Mena F, Varela E, Villaseñor L, Wang X, Watson IJ, Willox E, Yun-Cárcamo S, and Zhou H

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 measurement of the spatial morphology of a microquasar, SS 433, to TeV gamma rays 1 localizes the acceleration of electrons at shocks in the jet far from the black hole 2 . V4641 Sagittarii (V4641 Sgr) is a similar binary system with a black hole and B-type main-sequence companion star and has an orbit period of 2.8 days (refs.  3,4 ). It stands out for its super-Eddington accretion 5 and for its radio jet, which is one of the fastest superluminal jets in the Milky Way. Previous observations of V4641 Sgr did not report gamma-ray emission 6 . Here we report TeV gamma-ray emission from V4641 Sgr that reveals particle acceleration at similar distances from the black hole as SS 433. Furthermore, the gamma-ray spectrum of V4641 Sgr is among the hardest TeV spectra observed from any known gamma-ray source and is detected above 200 TeV. Gamma rays are produced by particles, either electrons or protons, of higher energies. Because energetic 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 protons. This suggests that large-scale jets from microquasars could be more common than previously expected and that they could be a notable source of galactic cosmic rays 7-9 ., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Published
2024
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22. Discovery of Gamma Rays from the Quiescent Sun with HAWC.

Author

Albert A, Alfaro R, Alvarez C, Arteaga-Velázquez JC, Avila Rojas D, Ayala Solares HA, Babu R, Belmont-Moreno E, Brisbois C, Caballero-Mora KS, Capistrán T, Carramiñana A, Casanova S, Chaparro-Amaro O, Cotti U, Cotzomi J, Coutiño de León S, De la Fuente E, Diaz Hernandez R, Dingus BL, DuVernois MA, Durocher M, Díaz-Vélez JC, Ellsworth RW, Engel K, Espinoza C, Fan KL, Fang K, Fernández Alonso M, Fleischhack H, Fraija N, García-González JA, Garfias F, González MM, Goodman JA, Harding JP, Hernandez S, Hinton J, Huang D, Hueyotl-Zahuantitla F, Hüntemeyer P, Iriarte A, Joshi V, Kaufmann S, Lee J, Linnemann JT, Longinotti AL, Luis-Raya G, Malone K, Martinez O, Martínez-Castro J, Matthews JA, Miranda-Romagnoli P, Morales-Soto JA, Moreno E, Mostafá M, Nayerhoda A, Nellen L, Nisa MU, Noriega-Papaqui R, Olivera-Nieto L, Omodei N, Pérez Araujo Y, Pérez-Pérez EG, Rho CD, Rosa-González D, Ruiz-Velasco E, Salazar H, Salazar-Gallegos D, Sandoval A, Schneider M, Serna-Franco J, Smith AJ, Son Y, Springer RW, Tibolla O, Tollefson K, Torres I, Torres-Escobedo R, Turner R, Ureña-Mena F, Varela E, Villaseñor L, Wang X, Watson IJ, Willox E, Yun-Cárcamo S, Zhou H, de León C, Beacom JF, Linden T, Ng KCY, Peter AHG, and Zhou B

Abstract

We report the first detection of a TeV γ-ray flux from the solar disk (6.3σ), 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  TeV)^{-γ}, with A=(1.6±0.3)×10^{-12}  TeV^{-1} cm^{-2} s^{-1} and γ=3.62±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.

Published
2023
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