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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. Spectral Study of Very-high-energy Gamma Rays from SS 433 with HAWC

Author: 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, J. Cotzomi, E. De la Fuente, D. Depaoli, N. Di Lalla, R. Diaz Hernandez, 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, 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, S. Kaufmann, A. Lara, W. H. Lee, J. Lee, C. de León, H. León Vargas, 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, 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, L. Villaseñor, X. Wang, Z. Wang, I. J. Watson, S. Yu, S. Yun-Cárcamo, H. Zhou, and HAWC collaboration
Subjects: Gamma-ray sources, High mass x-ray binary stars, Jets, Astrophysics, QB460-466
Abstract: Very-high-energy (0.1–100 TeV) gamma-ray emissions were observed in High-Altitude Water Cherenkov (HAWC) data from the lobes of the microquasar SS 433, making them the first set of astrophysical jets that were resolved at TeV energies. In this work, we update the analysis of SS 433 using 2565 days of data from the HAWC observatory. Our analysis reports the detection of a point-like source in the east lobe at a significance of 6.6 σ and in the west lobe at a significance of 8.2 σ . For each jet lobe, we localize the gamma-ray emission and identify a best-fit position. The locations are close to the X-ray emission sites “e1” and “w1” for the east and west lobes, respectively. We analyze the spectral energy distributions and find that the energy spectra of the lobes are consistent with a simple power law d N / d E ∝ E ^α with $\alpha =-{2.44}_{-0.12-0.04}^{+0.13+0.04}$ and $\alpha =-{2.35}_{-0.11-0.03}^{+0.12+0.03}$ for the east and west lobes, respectively. The maximum energy of photons from the east and west lobes reaches 56 TeV and 123 TeV, respectively. We compare our observations to various models and conclude that the very-high-energy gamma-ray emission can be produced by a population of electrons that were efficiently accelerated.
Published: 2024
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3. 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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4. Analysis of the Emission and Morphology of the Pulsar Wind Nebula Candidate HAWC J2031+415

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, 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, N. Fraija, J. A. García-González, 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, A. L. Longinotti, G. Luis-Raya, K. Malone, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, J. A. Montes, E. Moreno, M. Mostafá, M. Najafi, L. Nellen, M. Newbold, M. U. Nisa, R. Noriega-Papaqui, Y. Pérez Araujo, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, E. Ruiz-Velasco, H. Salazar, A. Sandoval, D. Salazar-Gallegos, 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, Zhen Wang, I. J. Watson, S. Yu, S. Yun-Cárcamo, H. Zhou, and THE HAWC COLLABORATION
Subjects: Gamma-ray astronomy, Pulsar wind nebulae, Binary pulsars, Gamma-ray sources, Astrophysics, QB460-466
Abstract: The first TeV γ -ray source with no lower energy counterparts, TeV J2032+4130, was discovered by HEGRA. It appears in the third HAWC catalog as 3HWC J2031+415 and it is a bright TeV γ -ray source whose emission has previously been resolved as two sources: HAWC J2031+415 and HAWC J2030+409. While HAWC J2030+409 has since been associated with the Fermi Large Area Telescope Cygnus Cocoon, no such association for HAWC J2031+415 has yet been found. In this work, we investigate the spectrum and energy-dependent morphology of HAWC J2031+415. We associate HAWC J2031+415 with a γ -ray binary system containing the pulsar PSR J2032+4127 and its companion MT91 213. We study HAWC data to observe their periastron in 2017. Additionally, we perform a combined multiwavelength analysis using radio, X-ray, and γ -ray emission. We conclude that HAWC J2031+415 and, by extension, TeV J2032+4130 are most probably a pulsar wind nebula powered by PSR J2032+4127.
Published: 2024
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5. 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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6. Multiwavelength Investigation of γ-Ray Source MGRO J1908+06 Emission Using Fermi-LAT, VERITAS and HAWC

Author: A. Acharyya, C. B. Adams, P. Bangale, J. T. Bartkoske, W. Benbow, J. H. Buckley, J. L. Christiansen, A. J. Chromey, A. Duerr, M. Errando, A. Falcone, Q. Feng, G. M. Foote, L. Fortson, A. Furniss, W. Hanlon, D. Hanna, O. Hervet, C. E. Hinrichs, J. Holder, T. B. Humensky, W. Jin, P. Kaaret, M. Kertzman, D. Kieda, T. K. Kleiner, N. Korzoun, S. Kumar, M. J. Lang, M. Lundy, G. Maier, C. E McGrath, M. J. Millard, J. Millis, C. L. Mooney, P. Moriarty, R. Mukherjee, W. Ning, R. A. Ong, N. Park, M. Pohl, E. Pueschel, J. Quinn, P. L. Rabinowitz, K. Ragan, D. Ribeiro, E. Roache, J. L. Ryan, I. Sadeh, L. Saha, G. H. Sembroski, R. Shang, M. Splettstoesser, A. K. Talluri, J. V. Tucci, J. Valverde, V. V. Vassiliev, A. Weinstein, D. A. Williams, S. L. Wong, J. Woo, The VERITAS Collaboration, R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez, D. Avila Rojas, R. Babu, E. Belmont-Moreno, A. Bernal, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, J. Cotzomi, S. Coutiño de León, E. De la Fuente, D. Depaoli, N. Di Lalla, R. Diaz Hernandez, M. A. DuVernois, C. Espinoza, K. L. Fan, K. Fang, N. Fraija, J. A. García-González, F. Garfias, M. M. González, J. A. Goodman, S. Groetsch, S. Hernández-Cadena, J. Hinton, D. Huang, F. Hueyotl-Zahuantitla, A. Iriarte, S. Kaufmann, J. Lee, H. León Vargas, A. L. Longinotti, G. Luis-Raya, K. Malone, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, J. A. Morales-Soto, E. Moreno, M. Mostafá, L. Nellen, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, H. Salazar, A. Sandoval, M. Schneider, J. Serna-Franco, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Ureña-Mena, E. Varela, X. Wang, H. Zhou, The HAWC Collaboration, J. Eagle, and The Fermi-LAT Collaboration
Subjects: Gamma-ray astronomy, Pulsar wind nebulae, Supernova remnants, Astrophysics, QB460-466
Abstract: This paper investigates the origin of the γ -ray emission from MGRO J1908+06 in the GeV–TeV energy band. By analyzing the data collected by the Fermi Large Area Telescope, the Very Energetic Radiation Imaging Telescope Array System, and High Altitude Water Cherenkov, with the addition of spectral data previously reported by LHAASO, a multiwavelength study of the morphological and spectral features of MGRO J1908+06 provides insight into the origin of the γ -ray emission. The mechanism behind the bright TeV emission is studied by constraining the magnetic field strength, the source age, and the distance through detailed broadband modeling. Both spectral shape and energy-dependent morphology support the scenario that inverse Compton emission of an evolved pulsar wind nebula associated with PSR J1907+0602 is responsible for the MGRO J1908+06 γ -ray emission with a best-fit true age of T = 22 ± 9 kyr and a magnetic field of B = 5.4 ± 0.8 μ G, assuming the distance to the pulsar d _PSR = 3.2 kpc.
Published: 2024
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7. 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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8. 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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9. GRB 221009A: Spectral Signatures Based on ALPs Candidates

Author: D. Avila Rojas, S. Hernández-Cadena, M. M. González, A. Pratts, R. Alfaro, and J. Serna-Franco
Subjects: Dark matter, High energy astrophysics, Gamma-ray bursts, Astrophysics, QB460-466
Abstract: GRB 221009A has posed a significant challenge to our current understanding of the mechanisms that produce TeV photons in gamma-ray bursts (GRBs). On one hand, the Klein–Nishina (KN) effect of the inverse Compton scattering leads to less efficient energy losses of high-energy electrons. On the other hand, at a redshift of 0.151, the TeV spectrum of GRB 221009A undergoes significant absorption by the extragalactic background light (EBL). Therefore, the observation of a 13 TeV photon in this event implies the presence of enormous photon fluxes at the source, which the synchrotron self-Compton mechanism in external shocks cannot easily generate. As an alternative, some authors have suggested the possibility of converting the TeV photons into axion-like particles (ALPs) at the host galaxy, in order to avoid the effects of EBL absorption, and then reconverting them into photons within the Milky Way. While this solution relaxes the requirement of very high photon fluxes, the KN effect still poses a challenge. Previously, we have shown that the injections of ALPs could explain the observation of 13 TeV photons. Here, we include the energy dependence of the probability of survival and the amount of energy carried to determine the ALP candidates, which could potentially explain the TeV photons observed by the Large High Altitude Air Shower Observatory and their hard spectrum. We found that the allowed candidates are generally clustered around masses of 10 ^−7 eV. We also considered different EBL models, for the one predicting larger attenuation tends to reject ALP candidates with the lowest coupling factor. For some hypotheses of the EBL model, these candidates are found below a region of the parameter space in which, if detected, ALPs could account for all of the cold dark matter in the Universe.
Published: 2024
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10. 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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11. 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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12. 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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13. GRB 221009A: A Light Dark Matter Burst or an Extremely Bright Inverse Compton Component?

Author: M. M. González, D. Avila Rojas, A. Pratts, S. Hernández-Cadena, N. Fraija, R. Alfaro, Y. Pérez Araujo, and J. A. Montes
Subjects: Dark matter, High energy astrophysics, Gamma-ray bursts, Astrophysics, QB460-466
Abstract: Gamma-ray bursts (GRBs) have been considered as potential very high energy photon emitters due to the large amount of energy released as well as the strong magnetic fields involved in their jets. However, the detection of teraelectronvolt photons is not expected from bursts beyond a redshift of z ≳ 0.1, due to their attenuation with the extragalactic background light (EBL). For these reasons, the recent observation of photons with energies of 18 and 251 TeV from GRB 221009A ( z = 0.151) last 2022 October 9 has challenged what we know about the teraelectronvolt-emission mechanisms and the extragalactic background. In order to explain the teraelectronvolt observations, recent works exploring candidates of dark matter have started to appear. In this paper, we discuss the required conditions and limitations within the most plausible scenario, synchrotron self-Compton radiation in the GRB afterglow, to interpret the one 18 TeV photon observation besides the EBL. To avoid the Klein–Nishina effect, we find an improbable value of the microphysical magnetic parameter below 10 ^−6 for a circumburst medium value >1 cm ^−3 (expected in the collapsar scenario). Therefore, we explore possible scenarios in terms of axion-like particles (ALPs) and dark photon mechanisms to interpret this highly energetic photon and we discuss the implications in the GRB energetics. We find that the ALPs and dark photon scenarios can explain the 18 teraelectronvolt photon but not the 251 teraelectronvolt photon.
Published: 2023
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14. 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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15. 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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16. 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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17. 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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18. MAGIC and Fermi-LAT gamma-ray results on unassociated HAWC sources

Author: M. L. Ahnen, S. Ansoldi, L. A. Antonelli, C. Arcaro, D. Baack, A. Babic, B. Banerjee, P. Bangale, U. Barres de Almeida, J. A. Barrio, J. Becerra Gonzalez, W. Bednarek, E. Bernardini, R. Ch. Berse, A. Berti, W. Bhattacharyya, A. Biland, O. Blanch, G. Bonnoli, R. Carosi, A. Carosi, G. Ceribella, A. Chatterjee, S. M. Colak, P. Colin, E. Colombo, J. L. Contreras, J. Cortina, S. Covino, P. Cumani, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, M. Delfino, J. Delgado, F. Di Pierro, A. Domınguez, D. Dominis Prester, D. Dorner, M. Doro, S. Einecke, D. Elsaesser, V. Fallah Ramazani, A. Fernandez-Barral, D. Fidalgo, M. V. Fonseca, L. Font, C. Fruck, D. Galindo, R. J. Garcıa Lopez, M. Garczarczyk, M. Gaug, P. Giammaria, N. Godinovic, D. Gora, D. Guberman, D. Hadasch, A. Hahn, T. Hassan, M. Hayashida, J. Herrera, J. Hose, D. Hrupec, K. Ishio, Y. Konno, H. Kubo, J. Kushida, D. Kuvezdic, D. Lelas, E. Lindfors, S. Lombardi, F. Longo, M. Lopez, C. Maggio, P. Majumdar, M. Makariev, G. Maneva, M. Manganaro, K. Mannheim, L. Maraschi, M. Mariotti, M. Martınez, S. Masuda, D. Mazin, K. Mielke, M. Minev, J. M. Miranda, R. Mirzoyan, A. Moralejo, V. Moreno, E. Moretti, T. Nagayoshi, V. Neustroev, A. Niedzwiecki, M. Nievas Rosillo, C. Nigro, K. Nilsson, D. Ninci, K. Nishijima, K. Noda, L. Nogues, S. Paiano, J. Palacio, D. Paneque, R. Paoletti, J. M. Paredes, G. Pedaletti, M. Peresano, M. Persic, P. G. Prada Moroni, E. Prandini, I. Puljak, J. R. Garcia, I. Reichardt, W. Rhodes, M. Ribo, J. Rico, C. Righi, A. Rugliancich, T. Saito, K. Satalecka, T. Schweizer, J. Sitarek, I. Snidaric, D. Sobczynska, A. Stamerra, M. Strzys, T. Suric, M. Takahashi, L. Takalo, F. Tavecchio, P. Temnikov, T. Terzic, M. Teshima, N. Torres-Alba, A. Treves, S. Tsujimoto, G. Vanzo, M. Vazquez Acosta, I. Vovk, J. E. Ward, M. Will, D. Zaric, A. Albert, R. Alfaro, C. Alvarez, R. Arceo, J. C. Arteaga-Velazquez, D. Avila Rojas, H. A. Ayala Solares, A. Becerril, E. Belmont-Moreno, S. Y. BenZvi, A. Bernal, J. Braun, K. S. Caballero-Mora, T. Capistran, A. Carraminana, S. Casanova, M. Castillo, U. Cotti, J. Cotzomi, S. Coutino de Leon, C. De Leon, E. De la Fuente, R. Diaz Hernandez, S. Dichiara, B. L. Dingus, M. A. DuVernois, J. C. Dıaz-Velez, R. W. Ellsworth, K. Engel, O. Enriquez-Rivera, D. W. Fiorino, H. Fleischhack, N. Fraija, J. A. Garcıa-Gonzalez, F. Garfias, A. Gonzalez-Munoz, M. M. Gonzalez, J. A. Goodman, Z. Hampel-Arias, J. P. Harding, S. Hernandez, F. Hueyotl-Zahuantitla, C. M. Hui, P. Huntemeyer, A. Iriarte, A. Jardin-Blicq, V. Joshi, S. Kaufmann, A. Lara, R. J. Lauer, W. H. Lee, D. Lennarz, H. Leon Vargas, J. T. Linnemann, A. L. Longinotti, G. Luis-Raya, R. Luna-Garcıa, R. Lopez-Coto, K. Malone, S. S. Marinelli, O. Martinez, I. Martinez-Castellanos, J. Martınez-Castro, H. Martınez-Huerta, J. A. Matthews, P. Miranda-Romagnoli, E. Moreno, A. Nayerhoda, L. Nellen, M. Newbold, M. U. Nisa, R. Noriega-Papaqui, R. Pelayo, J. Pretz, E. G. Perez-Perez, Z. Ren, C. D. Rho, C. Riviere, D. Rosa-Gonzalez, M. Rosenberg, E. Ruiz-Velasco, F. Salesa Greus, A. Sandoval, M. Schneider, M. Seglar Arroyo, G. Sinnis, A. J. Smith, R. W. Springer, P. Surajbali, I. Taboada, O. Tibolla, K. Tollefson, I. Torres, T. N. Ukwatta, G. Vianello, L. Villasenor, F. Werner, S. Westerhoff, J. Wood, T. Yapici, G. Yodh, A. Zepeda, H. Zhou, J. D. Alvarez, M. Ajello, L. Baldini, G. Barbiellini, B. Berenji, E. Bissaldi, R. D. Blandford, R. Bonino, E. Bottacini, T. J. Brandt, J. Bregeon, P. Bruel, R. A. Cameron, R. Caputo, P. A. Caraveo, D. Castro, E. Cavazzuti, G. Chiaro, S. Ciprini, D. Costantin, F. D'Ammando, F. de Palma, A. Desai, N. Di Lalla, M. Di Mauro, L. Di Venere, C. Favuzzi, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Giglietto, F. Giordano, M. Giroletti, T. Glanzman, D. Green, I. A. Grenier, S. Guiriec, A. K. Harding, E. Hays, J. W. Hewitt, D. Horan, G. Johannesson, M. Kuss, S. Larsson, I. Liodakis, F. Loparco, P. Lubrano, J. D. Magill, S. Maldera, A. Manfreda, M. N. Mazziotta, I. Mereu, P. F. Michelson, T. Mizuno, M. E. Monzani, A. Morselli, I. V. Moskalenko, M. Negro, E. Nuss, N. Omodei, M. Orienti, E. Orlando, J. F. Ormes, M. Palatiello, V. S. Paliya, M. Pesce-Rollins, V. Petrosian, F. Piron, T. A. Porter, G. Principe, S. Raino, B. Rani, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, C. Sgro, E. J. Siskind, G. Spandre, P. Spinelli, H. Tajima, J. B. Thayer, David J Thompson, D. F. Torres, E. Torresi, E. Troja, J. Valverde, K. Wood, and M. Yassine
Subjects: Astronomy, Astrophysics
Abstract: The HAWC Collaboration released the 2HWC catalogue of TeV sources, in which 19 show no association with any known high-energy (HE; E ≳ 10 GeV) or very-high-energy (VHE; E ≳ 300 GeV) sources. This catalogue motivated follow-up studies by both the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) and Fermi-LAT (Large Area Telescope) observatories with the aim of investigating gamma-ray emission over a broad energy band. In this paper, we report the results from the first joint work between High Altitude Water Cherenkov (HAWC), MAGIC, and Fermi-LAT on three unassociated HAWC sources: 2HWC J2006+341, 2HWC J1907+084*, and 2HWC J1852+013*. Although no significant detection was found in the HE and VHE regimes, this investigation shows that a minimum 1° extension (at 95 per cent confidence level) and harder spectrum in the GeV than the one extrapolated from HAWC results are required in the case of 2HWC J1852+013*, whilst a simply minimum extension of 0.16° (at 95 per cent confidence level) can already explain the scenario proposed by HAWC for the remaining sources. Moreover, the hypothesis that these sources are pulsar wind nebulae is also investigated in detail.
Published: 2019
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19. First HAWC observations of the Sun constrain steady TeV gamma-ray emission

Author: A. Albert, R. Alfaro, C. Alvarez, R. Arceo, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A. Ayala Solares, E. Belmont-Moreno, S. Y. BenZvi, C. Brisbois, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, M. Castillo, J. Cotzomi, S. Coutiño de León, C. De León, E. De la Fuente, S. Dichiara, B. L. Dingus, M. A. DuVernois, J. C. Díaz-Vélez, K. Engel, O. Enríquez-Rivera, C. Espinoza, H. Fleischhack, N. Fraija, J. A. García-González, F. Garfias, M. M. González, J. A. Goodman, Z. Hampel-Arias, J. P. Harding, S. Hernandez, B. Hona, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, A. Jardin-Blicq, V. Joshi, S. Kaufmann, H. León Vargas, G. Luis-Raya, J. Lundeen, R. López-Coto, K. Malone, S. S. Marinelli, O. Martinez, I. Martinez-Castellanos, J. Martínez-Castro, P. Miranda-Romagnoli, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, M. Newbold, M. U. Nisa, R. Noriega-Papaqui, J. Pretz, E. G. Pérez-Pérez, Z. Ren, C. D. Rho, C. Rivière, D. Rosa-González, M. Rosenberg, E. Ruiz-Velasco, H. Salazar, F. Salesa Greus, A. Sandoval, M. Schneider, H. Schoorlemmer, M. Seglar Arroyo, G. Sinnis, A. J. Smith, R. W. Springer, P. Surajbali, I. Taboada, O. Tibolla, K. Tollefson, I. Torres, L. Villaseñor, T. Weisgarber, S. Westerhoff, I. G. Wisher, J. Wood, T. Yapici, A. Zepeda, H. Zhou, J. D. Álvarez, J. F. Beacom, R. K. Leane, T. Linden, K. C. Y. Ng, A. H. G. Peter, and B. Zhou
Published: 2018
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20. Constraints on spin-dependent dark matter scattering with long-lived mediators from TeV observations of the Sun with HAWC

Author: A. Albert, R. Alfaro, C. Alvarez, R. Arceo, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A. Ayala Solares, E. Belmont-Moreno, S. Y. BenZvi, C. Brisbois, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, M. Castillo, J. Cotzomi, S. Coutiño de León, C. De León, E. De la Fuente, S. Dichiara, B. L. Dingus, M. A. DuVernois, J. C. Díaz-Vélez, K. Engel, O. Enríquez-Rivera, C. Espinoza, H. Fleischhack, N. Fraija, J. A. García-González, F. Garfias, M. M. González, J. A. Goodman, Z. Hampel-Arias, J. P. Harding, S. Hernandez, B. Hona, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, A. Jardin-Blicq, V. Joshi, S. Kaufmann, H. León Vargas, G. Luis-Raya, J. Lundeen, R. López-Coto, K. Malone, S. S. Marinelli, O. Martinez, I. Martinez-Castellanos, J. Martínez-Castro, P. Miranda-Romagnoli, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, M. Newbold, M. U. Nisa, R. Noriega-Papaqui, J. Pretz, E. G. Pérez-Pérez, Z. Ren, C. D. Rho, C. Rivière, D. Rosa-González, M. Rosenberg, E. Ruiz-Velasco, H. Salazar, F. Salesa Greus, A. Sandoval, M. Schneider, M. Seglar Arroyo, G. Sinnis, A. J. Smith, R. W. Springer, P. Surajbali, I. Taboada, O. Tibolla, K. Tollefson, I. Torres, L. Villaseñor, T. Weisgarber, S. Westerhoff, I. G. Wisher, J. Wood, T. Yapici, A. Zepeda, H. Zhou, J. D. Álvarez, J. F. Beacom, R. K. Leane, T. Linden, K. C. Y. Ng, A. H. G. Peter, and B. Zhou
Published: 2018
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21. 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

22. 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

23. 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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24. TeV Emission of Galactic Plane Sources with HAWC and H.E.S.S

Author: Nicola Omodei, Sebastian Panny, A. Sandoval, Q. Piel, S. Raab, Arturo Iriarte, Kirsty Feijen, R. D. Parsons, Michael Newbold, J. Zorn, Michael Schneider, Fernando Garfias, D. Huber, Christo Venter, Jacek Niemiec, Arnaud Mares, Frank M. Rieger, Thomas Weisgarber, A. Dmytriiev, Olaf Reimer, A. Zech, E. Ruiz-Velasco, Thomas Bylund, Y. A. Gallant, David Sánchez, R. López-Coto, Jorge Cotzomi, Jacques Muller, H. León Vargas, Alison Peisker, Justine Devin, Thomas Murach, P. Morris, Harm Schoorlemmer, Jonathan Mackey, Andrea Albert, Samuel Zouari, Pascal Vincent, M. Zacharias, Stefan Ohm, S. Pita, Tadayuki Takahashi, Gilgamesh Luis-Raya, A. Yusafzai, Andreas Quirrenbach, Samuel Timothy Spencer, Stefano Gabici, Regis Terrier, Victor Doroshenko, L. Nellen, Włodek Kluźniak, R. Noriega-Papaqui, E. Kasai, C. Moore, L. Oakes, J. Bolmont, Michal Ostrowski, J.-P. Lenain, Pooja Surajbali, William H. Lee, L. Olivera-Nieto, E. Moulin, Tomasz Bulik, Rhiannon Turner, Lente Dreyer, O. Martinez, Stefan Klepser, Alessandro Montanari, D. J. van der Walt, Fernando Ureña-Mena, J. P. Harding, César Alvarez, Michael DuVernois, A.M. Taylor, J. C. Arteaga-Velézquez, Connor Duffy, Davit Zargaryan, R. J. White, Stefan Funk, Alicja Wierzcholska, Dmitriy Kostunin, J. Damascene Mbarubucyeye, R. Rauth, Maria Magdalena González, Kristi Engel, A. Galván-Gámez, Christoph Deil, Krzysztof Katarzynski, F. Eichhorn, Mohanraj Senniappan, E. Moreno, Michael Punch, Axel Donath, B. Hona, A. W. Chen, S. Steinmassl, Sami Caroff, Domenico Tiziani, D. Malyshev, Catherine Boisson, M. Panter, Mora Durocher, U. Katz, Pedro Miranda-Romagnoli, C. Arcaro, H. Zhou, Michael Backes, S. Coutiño de León, Ernesto Belmont-Moreno, M. de Bony de Lavergne, R. Brose, Petra Hüntemeyer, C. Levy, Francois Brun, R. J. Tuffs, B. Bi, Andreas Specovius, Joachim Hahn, K. P. Arunbabu, Riaan Steenkamp, Gavin Rowell, P. Reichherzer, James E. M. Watson, M. Bryan, E. de Oña Wilhelmi, Łukasz Stawarz, C. van Rensburg, Pierre Brun, Brenda Dingus, V. Marandon, J. A. Morales-Soto, M. Büchele, H. Prokoph, C. De León, A. Marcowith, V. Baghmanyan, J. Schäfer, Nu. Komin, Tim Holch, Q. Remy, H. M. Schutte, Isak Delberth Davids, A. Fiasson, Jean-Pierre Ernenwein, Hassan Abdalla, S. Hernandez, Jim Hinton, V. Sahakian, E. De la Fuente, F. Werner, Mischa Breuhaus, Luis Villaseñor, Yu Wun Wong, Hambeleleni Ndiyavala, D. Avila Rojas, G. Lamanna, K. S. Caballero-Mora, Roberta Zanin, G. Emery, Halim Ashkar, Fabian Leuschner, Heiko Salzmann, A. S. Seyffert, Kwok Lung Fan, M. Hörbe, T. Tavernier, Nissim Illich Fraija, P. T. O'Brien, Johannes Veh, S. Sailer, Dmitry Khangulyan, Gilles Maurin, S. J. Fegan, A. Djannati-Ataï, D. Jankowsky, J. Dyks, Celine Armand, M. Füßling, R. Marx, Dieter Horns, M. Tluczykont, F. Ait Benkhali, J. F. Glicenstein, M. U. Nisa, Marek Jamrozy, Clemens Hoischen, A. A. Zdziarski, A. Jardin-Blicq, E. O. Angüner, R. Diaz Hernandez, N. Shafi, Natalia Żywucka, M. de Naurois, Andrea Santangelo, K. Malone, Gwenael Giacinti, L. Sun, M.-H. Grondin, D. Garcia, M. Seglar-Arroyo, B. Khélifi, A. J. Smith, T. Capistrán, B. van Soelen, G. Hermann, Anna Barnacka, D. Gottschall, Anne Lemiere, B. Rudak, Markus Böttcher, K. Tollefson, Jhilik Majumdar, Helene Sol, T. Chand, C. Brisbois, Andreas Zmija, Tom Armstrong, Elijah Willox, Carlo Romoli, Alison Mitchell, R. Torres-Escobedo, Atreyee Sinha, Manuel Meyer, I. Martinez-Castellanos, Zorawar Wadiasingh, A. Priyana Noel, V. Barbosa Martins, C. van Eldik, M. Lemoine-Goumard, M. Tsirou, Michael Kreter, Anna Lia Longinotti, F. Schüssler, Dezhi Huang, Jose Andres Garcia-Gonzalez, Werner Hofmann, Monica Barnard, Juan Carlos Diaz-Velez, V. Poireau, Jimmy N.S. Shapopi, K. Nakashima, José Serna-Franco, G. Peron, Garret Cotter, Jacco Vink, A. Carraminana, Umberto Cotti, Jim Davies, M. A. Kastendieck, Thomas Lohse, K. Kosack, Paolo Marchegiani, Konrad Bernlöhr, Heinrich J. Völk, Sabrina Casanova, Catalina Espinoza, M. Renaud, D. Berge, G. Vasileiadis, F. Salesa Greus, I. Jung-Richardt, Kleopas Shiningayamwe, Gilles Fontaine, J. T. Linnemann, Lenka Tomankova, M. Mostafá, G. Fichet de Clairfontaine, R. Konno, Gianluca Giavitto, V. Joshi, B. Peyaud, G. Pühlhofer, J. A. Goodman, H. Odaka, A. Reimer, R. W. Ellsworth, R. W. Springer, M. Curyło, F. Hueyotl-Zahuantitla, E. G. Pérez-Pérez, Y. Pérez Araujo, A. Nayerhoda, Christian Stegmann, Stefan Wagner, Yasunobu Uchiyama, David Kieda, L. Mohrmann, Misao Sasaki, Markus Holler, Felix Jankowsky, Felix Aharonian, D. Glawion, Jesús Martínez-Castro, Segev BenZvi, Constantin Steppa, L. Giunti, D. A. Prokhorov, Ullrich Schwanke, L. Rinchiuso, J. A. Matthews, Ibrahim Torres, Rachel Simoni, A. Carosi, K. Egberts, S. Chandra, Ruben Alfaro, Sabrina Einecke, Iryna Lypova, Daniel Rosa-Gonzalez, Yvonne Becherini, M. Fernández Alonso, L. Dirson, G. Martí-Devesa, C. Trichard, Sylvia Zhu, P. J. Meintjes, J. H. E. Thiersen, Marion Spir-Jacob, Maria Haupt, C. D. Rho, Rafal Moderski, Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE (UMR_7585)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Particules de Montpellier (LUPM), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Gravitation and Astroparticle Physics Amsterdam, High Energy Astrophys. & Astropart. Phys (API, FNWI), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Collaboration, H.E.S.S., and Collaboration, HAWC
Subjects: High-energy astronomy, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, IACT, Field of view, 030226 pharmacology & pharmacy, 01 natural sciences, 03 medical and health sciences, 0302 clinical medicine, Observatory, 0103 physical sciences, High Energy Stereoscopic System, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Cherenkov radiation, media_common, Physics, [PHYS]Physics [physics], Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Galactic plane, Space and Planetary Science, Sky, Astrophysics - Instrumentation and Methods for Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], High energy astrophysics
Abstract: International audience; 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 γ-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 data sets, 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 γ-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. data set. Remaining differences in the overall γ-ray flux can be explained by the systematic uncertainties. Therefore, we confirm a consistent view of the γ-ray sky between WCD and IACT techniques.
Published: 2021
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25. HAWC as a Ground-Based Space-Weather Observatory

Author: A. Zepeda, K. P. Arunbabu, S. Hernandez, J. A. Goodman, Ernesto Belmont-Moreno, R. W. Springer, O. Tibolla, E. Moreno, Juan Carlos Diaz-Velez, J. R. Angeles Camacho, Jose Andres Garcia-Gonzalez, Gerd Joachim Kunde, L. Nellen, D. Garcia, E. G. Pérez-Pérez, V. Baghmanyan, K. Malone, C. Alvarez, Karen S. Caballero-Mora, J. A. Morales-Soto, E. Tabachnick, Dezhi Huang, Catalina Espinoza, E. De la Fuente, D. Avila Rojas, Gilgamesh Luis-Raya, Jesús Martínez-Castro, Luis Villaseñor, Segev BenZvi, Pedro Miranda-Romagnoli, Alison Peisker, John Matthews, A. Sandoval, James M. Ryan, J. C. Arteaga-Velázquez, Umberto Cotti, Binita Hona, Michael Newbold, C. De León, P. Colin-Farias, Ibrahim Torres, Jorge Cotzomi, Nissim Illich Fraija, A. Galván-Gámez, R. Torres-Escobedo, Brenda Dingus, Daniel Rosa-Gonzalez, Fernando Garfias, Tomás Capistrán, H. León Vargas, M. J. F. Rosenberg, Y. Pérez Araujo, Maria Magdalena González, J. P. Harding, A. Nayerhoda, Chang Dong Rho, Hongyan Zhou, Filiberto Hueyotl-Zahuantitla, Simone Dichiara, Arturo Iriarte, Chad Brisbois, Michael DuVernois, Anna Lia Longinotti, Humberto Ibarguen Salazar, V. Joshi, K. Tollefson, R. Noriega-Papaqui, S. Coutiño de León, Alejandro Lara, and O. Martinez
Subjects: Physics, Photomultiplier, 010504 meteorology & atmospheric sciences, Physics::Instrumentation and Detectors, Detector, Gamma ray, Astronomy and Astrophysics, Cosmic ray, Space weather, 01 natural sciences, Space and Planetary Science, Observatory, 0103 physical sciences, 010303 astronomy & astrophysics, Energy (signal processing), Cherenkov radiation, 0105 earth and related environmental sciences, Remote sensing
Abstract: The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is located close to the equator (latitude $18^{\circ }$ N), at an altitude of 4100 m above sea level. HAWC has 295 water Cherenkov detectors (WCD), each containing four photomultiplier tubes (PMT). The main purpose of HAWC is the determination of the energy and arrival direction of very high energy gamma rays produced by energetic processes in the universe, HAWC also has a scaler system which counts the arrival of secondary particles to the detector. In this work we show that the scaler system of HAWC is an ideal instrument for solar modulation and space-weather studies due to its large area and high sensitivity. In order to prepare the scaler system for low energy heliospheric studies, we model and correct the efficiency variation of each PMT of the array, which result in a capability to measure variations $> 0.01\%$ with high accuracy. Using the singular value decomposition method, we correct the rate deviations of all PMTs of the array, due to changes in efficiency, gain and operational voltage. We isolate and remove the atmospheric modulations of the PMTs count rates measured by the TDC-scaler data acquisition system. In particular, the atmospheric pressure at the HAWC site exhibits an oscillating behavior with a period of ∼12 hours and we make use of this periodic property to estimate the pressure coefficients for the HAWC TDC-scaler system. These corrections performed on the TDC-scaler system make the HAWC TDC-scaler system an ideal instrument for solar modulation and space-weather studies. As examples of this capability, we present the preliminary analysis of the solar modulation of cosmic rays at three time scales observed by HAWC, with an unprecedented accuracy.
Published: 2021
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26. HAWC Search for High-Mass Microquasars

Author: Ernesto Belmont-Moreno, Elijah Willox, J. A. Goodman, Dezhi Huang, Jorge Cotzomi, Mora Durocher, Petra Hüntemeyer, J. P. Harding, R. W. Springer, A. Carraminana, K. Malone, A. J. Smith, J. C. Arteaga-Velázquez, H. Zhou, Joe Lundeen, C. D. Rho, F. Salesa Greus, R. W. Ellsworth, C. De León, K. P. Arunbabu, A. L. Longinotti, David Kieda, B. Hona, Alison Peisker, L. Nellen, E. Moreno, Fernando Ureña-Mena, Umberto Cotti, R. Torres-Escobedo, C. Brisbois, Sabrina Casanova, R. Diaz Hernandez, Maria Magdalena González, S. Hernandez, Nissim Illich Fraija, Karen S. Caballero-Mora, Michael Newbold, Rhiannon Turner, Fernando Garfias, Michael DuVernois, Thomas Weisgarber, Catalina Espinoza, A. Sandoval, Jose Andres Garcia-Gonzalez, Filiberto Hueyotl-Zahuantitla, Jesús Martínez-Castro, Michael Schneider, H. A. Ayala Solares, Ke Fang, Y. J. Roh, Andrea Albert, T. Capistrán, O. Martinez, Ian James Watson, Miguel Mostafa, Gilgamesh Luis-Raya, V. Baghmanyan, V. Joshi, José Serna-Franco, Alejandro Lara, J. T. Linnemann, R. Noriega-Papaqui, William H. Lee, L. Olivera-Nieto, J. S. H. Lee, A. Galván-Gámez, Brenda Dingus, K. Tollefson, Ruben Alfaro, Pedro Miranda-Romagnoli, Daniel Rosa-Gonzalez, John Matthews, J. A. Morales-Soto, Luis Villaseñor, Kwok Lung Fan, H. León Vargas, A. Jardin-Blicq, Ibrahim Torres, M. U. Nisa, Juan Carlos Diaz-Velez, C. Alvarez, Nicola Omodei, Arturo Iriarte, Y. Pérez Araujo, A. Nayerhoda, Segev BenZvi, E. De la Fuente, D. Avila Rojas, and J. R. Angeles Camacho
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Space and Planetary Science, Astrophysics::High Energy Astrophysical Phenomena, High mass, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: Microquasars with high-mass companion stars are promising very-high-energy (VHE; 0.1-100 TeV) gamma-ray emitters, but their behaviors above 10 TeV are poorly known. Using the High Altitude Water Cherenkov (HAWC) observatory, we search for excess gamma-ray emission coincident with the positions of known high-mass microquasars (HMMQs). No significant emission is observed for LS 5039, Cygnus X-1, Cygnus X-3, and SS 433 with 1,523 days of HAWC data. We set the most stringent limit above 10 TeV obtained to date on each individual source. Under the assumption that HMMQs produce gamma rays via a common mechanism, we have performed source-stacking searches, considering two different scenarios: I) gamma-ray luminosity is a fraction $\epsilon_\gamma$ of the microquasar jet luminosity, and II) very-high-energy gamma rays are produced by relativistic electrons up-scattering the radiation field of the companion star in a magnetic field $B$. We obtain $\epsilon_\gamma < 5.4\times 10^{-6}$ for scenario I, which tightly constrains models that suggest observable high-energy neutrino emission by HMMQs. In the case of scenario II, the non-detection of VHE gamma rays yields a strong magnetic field, which challenges synchrotron radiation as the dominant mechanism of the microquasar emission between 10 keV and 10 MeV., Comment: Accepted for publication in ApJL
Published: 2021

27. Evidence that Ultra-High-Energy Gamma Rays are a Universal Feature Near Powerful Pulsars

Author: R. Diaz Hernandez, Pedro Miranda-Romagnoli, J. A. Goodman, J. R. Angeles Camacho, Michael Newbold, Karen S. Caballero-Mora, Catalina Espinoza, John Matthews, Fernando Garfias, Jesús Martínez-Castro, H. A. Ayala Solares, Andrea Albert, Segev BenZvi, C. D. Rho, Thomas Weisgarber, Nicola Omodei, Dezhi Huang, Nissim Illich Fraija, E. Ruiz-Velasco, R. Torres-Escobedo, Ibrahim Torres, Arturo Iriarte, H. León Vargas, A. Carraminana, Joe Lundeen, R. W. Ellsworth, Meghan Tanner, C. De León, A. Sandoval, O. Martinez, K. Malone, J. C. Arteaga-Velázquez, Ernesto Belmont-Moreno, R. W. Springer, Michael Schneider, Alison Peisker, H. Zhou, E. G. Pérez-Pérez, K. P. Arunbabu, A. L. Longinotti, Kristi Engel, Harm Schoorlemmer, B. Hona, A. Jardin-Blicq, Elijah Willox, J. D. Álvarez, J. A. Morales-Soto, T. Capistrán, A. J. Smith, David Kieda, Humberto Ibarguen Salazar, Y. Pérez Araujo, J. P. Harding, Gwenael Giacinti, Gilgamesh Luis-Raya, L. Nellen, A. Nayerhoda, R. Noriega-Papaqui, Juan Carlos Diaz-Velez, S. Hernandez, Ruben Alfaro, William H. Lee, L. Olivera-Nieto, M. Fernández Alonso, C. Alvarez, Y. J. Roh, Miguel Mostafa, Daniel Rosa-Gonzalez, José Serna-Franco, Luis Villaseñor, Umberto Cotti, E. De la Fuente, Sabrina Casanova, D. Avila Rojas, V. Joshi, F. Salesa Greus, S. Coutiño de León, M. U. Nisa, Jorge Cotzomi, Alejandro Lara, J. T. Linnemann, Rhiannon Turner, Maria Magdalena González, Michael DuVernois, Kwok Lung Fan, Filiberto Hueyotl-Zahuantitla, J. S. H. Lee, E. Moreno, A. Galván-Gámez, Brenda Dingus, V. Marandon, K. Tollefson, C. Brisbois, V. Baghmanyan, Mora Durocher, Petra Hüntemeyer, Pooja Surajbali, Fernando Ureña-Mena, and Jose Andres Garcia-Gonzalez
Subjects: Astroparticle physics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), High energy, High-energy astronomy, Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Pulsar, Space and Planetary Science, Feature (computer vision), Astrophysics - High Energy Astrophysical Phenomena
Abstract: The highest-energy known gamma-ray sources are all located within 0.5 degrees of extremely powerful pulsars. This raises the question of whether ultra-high-energy (UHE; $>$ 56 TeV) gamma-ray emission is a universal feature expected near pulsars with a high spin-down power. Using four years of data from the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory, we present a joint-likelihood analysis of ten extremely powerful pulsars to search for UHE gamma-ray emission correlated with these locations. We report a significant detection ($>$ 3$��$), indicating that UHE gamma-ray emission is a generic feature of powerful pulsars. We discuss the emission mechanisms of the gamma rays and the implications of this result. The individual environment that each pulsar is found in appears to play a role in the amount of emission., accepted by ApJL
Published: 2021

28. 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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29. Probing the Sea of Cosmic Rays by Measuring Gamma-Ray Emission from Passive Giant Molecular Clouds with HAWC

Author: Segev BenZvi, C. Alvarez, S. Coutiño de León, A. Sandoval, Alejandro Lara, Pooja Surajbali, S. Hernandez, E. De la Fuente, Fernando Ureña-Mena, D. Avila Rojas, R. Diaz Hernandez, Andrea Albert, Michael Schneider, K. Malone, Fernando Garfias, H. Zhou, E. Ruiz-Velasco, C. Brisbois, K. P. Arunbabu, Mora Durocher, Petra Hüntemeyer, A. L. Longinotti, O. Martinez, J. S. H. Lee, D. Garcia, H. León Vargas, J. A. Morales-Soto, A. Galván-Gámez, Nicola Omodei, J. A. Goodman, Meghan Tanner, Arturo Iriarte, Brenda Dingus, Y. Pérez Araujo, J. C. Arteaga-Velázquez, Michael Newbold, Alison Peisker, A. Nayerhoda, Juan Carlos Diaz-Velez, Luis Villaseñor, Jose Andres Garcia-Gonzalez, J. R. Angeles Camacho, Ernesto Belmont-Moreno, E. Moreno, Miguel Mostafa, B. Hona, Kwok Lung Fan, Umberto Cotti, K. Tollefson, Kristi Engel, Nissim Illich Fraija, J. P. Harding, T. Weisgarber, Maria Magdalena González, V. Joshi, Sabrina Casanova, M. U. Nisa, J. A. Matthews, Karen S. Caballero-Mora, Ibrahim Torres, V. Baghmanyan, Elijah Willox, Jorge Cotzomi, Catalina Espinoza, José Serna-Franco, Gilgamesh Luis-Raya, Filiberto Hueyotl-Zahuantitla, Jesús Martínez-Castro, H. A. Ayala Solares, Ruben Alfaro, C. D. Rho, R. Noriega-Papaqui, Dezhi Huang, Pedro Miranda-Romagnoli, J. T. Linnemann, William H. Lee, Daniel Rosa-Gonzalez, T. Capistrán, M. Fernández Alonso, R. Torres-Escobedo, A. J. Smith, R. W. Springer, L. Nellen, E. G. Pérez-Pérez, David Kieda, C. De León, F. Salesa Greus, Rhiannon Turner, Michael DuVernois, A. Carraminana, Joe Lundeen, and R. W. Ellsworth
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), High-energy astronomy, Molecular cloud, Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, FOS: Physical sciences, Astronomy and Astrophysics, Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics
Abstract: The study of high-energy gamma rays from passive Giant Molecular Clouds (GMCs) in our Galaxy is an indirect way to characterize and probe the paradigm of the "sea" of cosmic rays in distant parts of the Galaxy. By using data from the High Altitude Water Cherenkov (HAWC) observatory, we measure the gamma-ray flux above 1 TeV of a set of these clouds to test the paradigm. We selected high-galactic latitude clouds that are in HAWC's field-of-view and which are within 1~kpc distance from the Sun. We find no significant excess emission in the cloud regions, nor when we perform a stacked log-likelihood analysis of GMCs. Using a Bayesian approach, we calculate 95\% credible intervals upper limits of the gamma-ray flux and estimate limits on the cosmic-ray energy density of these regions. These are the first limits to constrain gamma-ray emission in the multi-TeV energy range ($>$1 TeV) using passive high-galactic latitude GMCs. Assuming that the main gamma-ray production mechanism is due to proton-proton interaction, the upper limits are consistent with a cosmic-ray flux and energy density similar to that measured at Earth., 6 figures, 6 tables
Published: 2021
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30. Spectrum and morphology of the very-high-energy source HAWC J2019+368

Author: R. W. Springer, C. D. Rho, E. G. Pérez-Pérez, Alison Peisker, A. J. Smith, J. A. Morales-Soto, E. Moreno, Sabrina Casanova, V. Joshi, Dezhi Huang, Rhiannon Turner, Michael DuVernois, L. Nellen, A. Carraminana, T. Capistrán, Joe Lundeen, J. P. Harding, Gwenael Giacinti, Jorge Cotzomi, J. C. Arteaga-Velázquez, Karen S. Caballero-Mora, Nicola Omodei, Jose Andres Garcia-Gonzalez, S. Coutiño de León, T. Weisgarber, V. Baghmanyan, Catalina Espinoza, J. A. Goodman, D. Garcia, Nissim Illich Fraija, H. Zhou, A. Jardin-Blicq, Jesús Martínez-Castro, H. A. Ayala Solares, K. P. Arunbabu, A. L. Longinotti, A. Sandoval, Ernesto Belmont-Moreno, Humberto Ibarguen Salazar, O. Martinez, Jim Hinton, Andrea Albert, Michael Schneider, P. Huentemeyer, Miguel Mostafa, C. Brisbois, Harm Schoorlemmer, M. U. Nisa, R. Noriega-Papaqui, Binita Hona, Elijah Willox, Pooja Surajbali, Brenda Dingus, William H. Lee, L. Olivera-Nieto, Michael Newbold, José Serna-Franco, R. Diaz Hernandez, Fernando Ureña-Mena, Pedro Miranda-Romagnoli, R. López-Coto, K. Tollefson, Y. Pérez Araujo, E. Ruiz-Velasco, A. Nayerhoda, J. T. Linnemann, F. Salesa Greus, Ibrahim Torres, Mora Durocher, H. León Vargas, C. Alvarez, Maria Magdalena González, E. De la Fuente, C. De León, D. Avila Rojas, Filiberto Hueyotl-Zahuantitla, Gilgamesh Luis-Raya, K. Malone, John Matthews, Ruben Alfaro, Daniel Rosa-Gonzalez, and Kristi Engel
Subjects: Energy dependent, Physics, High energy, Nebula, 010504 meteorology & atmospheric sciences, media_common.quotation_subject, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Pulsar wind nebula, Pulsar, Space and Planetary Science, Sky, 0103 physical sciences, Supernova remnant, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, media_common
Abstract: The MGRO J2019+37 region is one of the brightest sources in the sky at TeV energies. It was detected in the second 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 ∼7 kyr pulsar and nebula system producing the observed emission at X-ray and γ-ray energies.
Published: 2021

31. 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

32. A survey of active galaxies at TeV photon energies with the HAWC gamma-ray observatory

Author: Andrea Albert, Fernando Garfias, Kristi Engel, K. Tollefson, A. Zepeda, E. Ruiz-Velasco, H. León Vargas, Segev BenZvi, Binita Hona, H. Zhou, K. P. Arunbabu, J. A. Morales-Soto, C. Brisbois, Karen S. Caballero-Mora, Jose Andres Garcia-Gonzalez, Ernesto Belmont-Moreno, Pedro Miranda-Romagnoli, Catalina Espinoza, S. Coutiño de León, J. R. Angeles Camacho, Jesús Martínez-Castro, F. Salesa Greus, H. A. Ayala Solares, A. Carraminana, Luis Villaseñor, Daniel Rosa-Gonzalez, E. Moreno, Alejandro Lara, R. W. Springer, Joe Lundeen, C. De León, Alison Peisker, Kwok Lung Fan, E. G. Pérez-Pérez, O. Martinez, J. C. Arteaga-Velázquez, Elijah Willox, Gerd Joachim Kunde, Henrike Fleischhack, Fernando Ureña-Mena, John Matthews, Harm Schoorlemmer, Ibrahim Torres, R. Torres-Escobedo, Gilgamesh Luis-Raya, David Kieda, V. Baghmanyan, R. Noriega-Papaqui, William H. Lee, L. Olivera-Nieto, I. Martinez-Castellanos, C. D. Rho, Mora Durocher, Petra Hüntemeyer, A. Sandoval, A. J. Smith, M. U. Nisa, K. Malone, Michael Schneider, Jorge Cotzomi, S. Hernandez, J. A. Goodman, Michael DuVernois, A. Jardin-Blicq, Nissim Illich Fraija, Dezhi Huang, D. Garcia, J. P. Harding, T. Weisgarber, A. Nayerhoda, Arturo Iriarte, Michael Newbold, Juan Carlos Diaz-Velez, J. T. Linnemann, Tomás Capistrán, C. Alvarez, E. De la Fuente, D. Avila Rojas, A. Galván-Gámez, Brenda Dingus, Anna Lia Longinotti, Humberto Ibarguen Salazar, Umberto Cotti, Maria Magdalena González, Miguel Mostafa, Sabrina Casanova, M. Fernández Alonso, V. Joshi, Filiberto Hueyotl-Zahuantitla, and L. Nellen
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Active galactic nucleus, Radio galaxy, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Extragalactic background light, Space and Planetary Science, Observatory, Sky, Blazar, Astrophysics - High Energy Astrophysical Phenomena, Cherenkov radiation, media_common
Abstract: The High Altitude Water Cherenkov Gamma-Ray Observatory (HAWC) continuously detects TeV photons and particles within its large field-of-view, accumulating every day a deeper exposure of two thirds of the sky. We analyzed 1523~days of HAWC live data acquired over four and a half years, in a follow-up analysis of {138} nearby ($z, Comment: The HAWC survey of Fermi 3FHL AGNs: 30 pages, 13 figures. Submitted to the Astrophysical Journal
Published: 2020

33. 3HWC: The Third HAWC Catalog of Very-High-Energy Gamma-ray Sources

Author: Michael Newbold, O. Martinez, Segev BenZvi, F. Serna, Pooja Surajbali, Gus Sinnis, Fernando Garfias, S. Hernandez, A. Zepeda, Fernando Ureña-Mena, E. Ruiz-Velasco, H. Zhou, Y. Pérez Araujo, Nicola Omodei, Arturo Iriarte, A. Nayerhoda, L. Diaz-Cruz, K. P. Arunbabu, A. L. Longinotti, R. Diaz Hernandez, Mora Durocher, Petra Hüntemeyer, A. Sandoval, H. León Vargas, J. A. Morales-Soto, Michael Schneider, A. Jardin-Blicq, J. C. Arteaga-Velázquez, Harm Schoorlemmer, B. Hona, Gilgamesh Luis-Raya, K. Malone, T. N. Ukwatta, R. Noriega-Papaqui, Andrea Albert, Tomás Capistrán, Kwok Lung Fan, Humberto Ibarguen Salazar, William H. Lee, L. Olivera-Nieto, V. Baghmanyan, Alison Peisker, C. Brisbois, Henrike Fleischhack, A. Carraminana, Jose Andres Garcia-Gonzalez, C. Rivière, Mehr Nisa, Miguel Mostafa, D. Garcia, Joe Lundeen, Juan Carlos Diaz-Velez, John Matthews, R. López-Coto, J. P. Harding, R. W. Ellsworth, S. Coutiño de León, T. Weisgarber, V. Joshi, J. R. Angeles Camacho, Alejandro Lara, A. J. Smith, Ibrahim Torres, L. Nellen, J. D. Álvarez, Ke Fang, Ruben Alfaro, K. Tollefson, F. Salesa Greus, Daniel Rosa-Gonzalez, M. Fernández Alonso, C. Alvarez, Kristi Engel, Michael DuVernois, C. De León, E. De la Fuente, J. T. Linnemann, F. Werner, D. Avila Rojas, J. A. Goodman, Pedro Miranda-Romagnoli, Dezhi Huang, A. Galván-Gámez, Brenda Dingus, V. Marandon, Karen S. Caballero-Mora, Catalina Espinoza, Jesús Martínez-Castro, H. A. Ayala Solares, Gwenael Giacinti, I. Martinez-Castellanos, R. Torres-Escobedo, E. Moreno, R. W. Springer, E. G. Pérez-Pérez, David Kieda, Umberto Cotti, Sabrina Casanova, Ernesto Belmont-Moreno, Nissim Illich Fraija, Jim Hinton, Maria Magdalena González, Elijah Willox, Z. Ren, Filiberto Hueyotl-Zahuantitla, and C. D. Rho
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), High energy, High-energy astronomy, Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Gamma-ray astronomy, Astrophysics::Cosmology and Extragalactic Astrophysics, Pulsar, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics
Abstract: We present a new catalog of TeV gamma-ray sources using 1523 days of data from the High Altitude Water Cherenkov (HAWC) observatory. The catalog represents the most sensitive survey of the Northern gamma-ray sky at energies above several TeV, with three times the exposure compared to the previous HAWC catalog, 2HWC. We report 65 sources detected at $\geq$ 5 sigma significance, along with the positions and spectral fits for each source. The catalog contains eight sources that have no counterpart in the 2HWC catalog, but are within $1^\circ$ of previously detected TeV emitters, and twenty sources that are more than $1^\circ$ away from any previously detected TeV source. Of these twenty new sources, fourteen have a potential counterpart in the fourth \textit{Fermi} Large Area Telescope catalog of gamma-ray sources. We also explore potential associations of 3HWC sources with pulsars in the ATNF pulsar catalog and supernova remnants in the Galactic supernova remnant catalog., 20 pages, 11 figures. Matches the version published in The Astrophysical Journal. See accompanying data release at https://data.hawc-observatory.org/datasets/3hwc-survey/index.php
Published: 2020

34. HAWC J2227+610 and its association with G106.3+2.7, a new potential Galactic PeVatron

Author: E. Moreno, P. Hüntemeyer, R. Torres-Escobedo, Armelle Jardin-Blicq, R. Noriega-Papaqui, J. T. Linnemann, E. G. Pérez-Pérez, Karen S. Caballero-Mora, J. A. Goodman, J. R. Angeles Camacho, K. Tollefson, Catalina Espinoza, H. León Vargas, H. A. Ayala Solares, J. A. Morales-Soto, Segev BenZvi, A. Galván-Gámez, Luis Villaseñor, Sabrina Casanova, V. Joshi, K. Malone, K. P. Arunbabu, Kwok Lung Fan, D. Garcia, S. Hernandez, U. Cotti, Arnulfo Zepeda, E. De la Fuente, S. S. Marinelli, D. Avila Rojas, E. Belmont-Moreno, Mehr Nisa, Nicola Omodei, H. Schoorlemmer, Andrea Albert, J. P. Harding, F. Garfias, M. Newbold, A. Iriarte, J. D. Álvarez, E. Tabachnick, P. Surajbali, Meghan Tanner, A. J. Smith, B. Hona, C. De León, M. Fernández Alonso, T. Capistrán, P. Miranda-Romagnoli, A. Sandoval, G. Luis-Raya, R. W. Ellsworth, Michael Schneider, Jose Andres Garcia-Gonzalez, E. Ruiz-Velasco, S. Coutiño de León, C. Brisbois, M. Mostafá, Y. Pérez Araujo, J. C. Díaz-Vélez, R. W. Springer, Daniel Rosa-Gonzalez, Amid Nayerhoda, T. Weisgarber, Brenda Dingus, Maria Magdalena González, Nissim Fraija, G. Sinnis, Ke Fang, H. Salazar, Lukas Nellen, Hongyan Zhou, J.C. Arteaga-Velázquez, Michael DuVernois, A. Carramiñana, I. Torres, Gwenael Giacinti, F. Ureña-Mena, Filiberto Hueyotl-Zahuantitla, J. Serna Franco, I. Martinez-Castellanos, C. Alvarez, K. Engel, Ruben Alfaro, C. D. Rho, F. Salesa Greus, A. L. Longinotti, W. H. Lee, A. Peisker, L. Diaz-Cruz, D. Huang, J. Cotzomi, J. Martínez-Castro, O. Tibolla, Henrike Fleischhack, J. Hinton, J. Lundeen, Vardan Baghmanyan, John Matthews, Oscar Martinez, and HAWC Collaboration
Subjects: HAWC - Abteilung Hinton, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Hydrogen compounds, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Lower limit, Galaxy, Space and Planetary Science, Observatory, 0103 physical sciences, Supernova remnant, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences
Abstract: We present the detection of VHE gamma-ray emission above 100 TeV from HAWC J2227+610 with the HAWC observatory. Combining our observations with previously published results by VERITAS, we interpret the gamma-ray emission from HAWC J2227+610 as emission from protons with a lower limit in their cutoff energy of 800 TeV. The most likely source of the protons is the associated supernova remnant G106.3+2.7, making it a good candidate for a Galactic PeVatron. However, a purely leptonic origin of the observed emission cannot be excluded at this time., Accepted for publication by ApJL
Published: 2020

35. HAWC and Fermi-LAT Detection of Extended Emission from the Unidentified Source 2HWC J2006+341

Author: E. Moreno, Nissim Illich Fraija, Nicola Omodei, Pedro Miranda-Romagnoli, Alison Peisker, Arturo Iriarte, L. Nellen, Henrike Fleischhack, Fernando Ureña-Mena, C. Alvarez, Andrea Albert, F. Salesa Greus, Mora Durocher, Petra Hüntemeyer, A. Zepeda, D. Garcia, R. W. Springer, Mehr Nisa, C. Brisbois, H. Zhou, Miguel Mostafa, E. G. Pérez-Pérez, E. De la Fuente, John Matthews, D. Avila Rojas, K. P. Arunbabu, Michael DuVernois, Ibrahim Torres, V. Joshi, A. Galván-Gámez, C. De León, Jose Andres Garcia-Gonzalez, R. Torres-Escobedo, R. Diaz Hernandez, K. Malone, Miguel Araya, A. Carraminana, V. Baghmanyan, Brenda Dingus, Karen S. Caballero-Mora, Catalina Espinoza, R. López-Coto, Anna Lia Longinotti, Jesús Martínez-Castro, Joe Lundeen, H. A. Ayala Solares, K. Tollefson, O. Martinez, A. Jardin-Blicq, Ruben Alfaro, Gilgamesh Luis-Raya, Juan Carlos Diaz-Velez, J. R. Angeles Camacho, Umberto Cotti, Daniel Rosa-Gonzalez, Sabrina Casanova, R. Noriega-Papaqui, J. T. Linnemann, Dezhi Huang, J. C. Arteaga-Velázquez, B. Hona, J. A. Goodman, Fernando Garfias, Maria Magdalena González, Ernesto Belmont-Moreno, Filiberto Hueyotl-Zahuantitla, H. León Vargas, A. Sandoval, Michael Schneider, Elijah Willox, J. P. Harding, C. D. Rho, T. Weisgarber, and Luis Villaseñor
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Interstellar medium, Space and Planetary Science, 0103 physical sciences, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Fermi Gamma-ray Space Telescope
Abstract: The discovery of the TeV point source 2HWC J2006+341 was reported in the second HAWC gamma-ray catalog. We present a follow-up study of this source here. The TeV emission is best described by an extended source with a soft spectrum. At GeV energies, an extended source is significantly detected in Fermi-LAT data. The matching locations, sizes and spectra suggest that both gamma-ray detections correspond to the same source. Different scenarios for the origin of the emission are considered and we rule out an association to the pulsar PSR J2004+3429 due to extreme energetics required, if located at a distance of 10.8 kpc., Comment: 12 pages, 2 figures. To appear in ApJL
Published: 2020
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36. Constraining the local burst rate density of primordial black holes with HAWC

Author: E. G. Pérez-Pérez, U. Cotti, S. Hernandez, A. J. Smith, T. Capistrán, J.C. Arteaga-Velázquez, K. Malone, W. H. Lee, J. Cotzomi, E. Tabachnick, R. Noriega-Papaqui, E. Belmont-Moreno, A. Iriarte, Joe Lundeen, B. Hona, S. S. Marinelli, Lukas Nellen, Hao Zhou, Alejandro Lara, G. Sinnis, Michael DuVernois, F. Garfias, I. Torres, A. Carramiñana, K. Tollefson, J. Martínez-Castro, Mehr Nisa, C. D. Rho, J. C. Díaz-Vélez, Nissim Fraija, O. Tibolla, C. De León, I. Martinez-Castellanos, E. De la Fuente, Karen S. Caballero-Mora, G. Luis-Raya, R. W. Ellsworth, H. Fleischhack, R. López-Coto, K. Engel, F. Salesa Greus, C. Brisbois, Jose Andres Garcia-Gonzalez, R. W. Springer, A. Galván-Gámez, Sabrina Casanova, H. Martínez-Huerta, V. Joshi, Brenda Dingus, Catalina Espinoza, John N. Wood, H. Salazar, Segev BenZvi, C. Alvarez, Vardan Baghmanyan, A. L. Longinotti, Alison Peisker, John Matthews, K. P. Arunbabu, Oscar Martinez, D. Avila Rojas, H. A. Ayala Solares, Daniel Rosa-Gonzalez, Amid Nayerhoda, Andrea Albert, M. Newbold, M. J. F. Rosenberg, Meghan Tanner, P. Miranda-Romagnoli, P. Hüntemeyer, R. Torres-Escobedo, J. P. Harding, C. Rivière, J. T. Linnemann, Maria Magdalena González, A. Sandoval, J. A. Goodman, Michael Schneider, H. León Vargas, Dezhi Huang, J. A. Morales-Soto, M. Mostafá, Filiberto Hueyotl-Zahuantitla, T. Weisgarber, Arnulfo Zepeda, Ruben Alfaro, and E. Moreno
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Solar mass, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, Gamma ray, FOS: Physical sciences, Astronomy and Astrophysics, Primordial black hole, Astrophysics, Universe, High Energy Physics - Experiment, 85-05, Black hole, High Energy Physics - Experiment (hep-ex), RAIOS GAMA, Observatory, Astrophysics - High Energy Astrophysical Phenomena, Cherenkov radiation, Hawking radiation, media_common
Abstract: Primordial Black Holes (PBHs) may have been created by density fluctuations in the early Universe and could be as massive as $> 10^9$ solar masses or as small as the Planck mass. It has been postulated that a black hole has a temperature inversely-proportional to its mass and will thermally emit all species of fundamental particles via Hawking Radiation. PBHs with initial masses of $\sim 5 \times 10^{14}$ g (approximately one gigaton) should be expiring today with bursts of high-energy gamma radiation in the GeV--TeV energy range. The High Altitude Water Cherenkov (HAWC) Observatory is sensitive to gamma rays with energies of $\sim$300 GeV to past 100 TeV, which corresponds to the high end of the PBH burst spectrum. With its large instantaneous field-of-view of $\sim 2$ sr and a duty cycle over 95%, the HAWC Observatory is well suited to perform an all-sky search for PBH bursts. We conducted a search using 959 days of HAWC data and exclude the local PBH burst rate density above $3400~\mathrm{pc^{-3}~yr^{-1}}$ at 99% confidence, the strongest limit on the local PBH burst rate density from any existing electromagnetic measurement., Corresponding authors: K.L. Engel & A. Peisker. 13 pages, 5 figures
Published: 2020

37. Author Correction: HAWC observations of the acceleration of very-high-energy cosmic rays in the Cygnus Cocoon

Author: A. Jardin-Blicq, J. A. Morales-Soto, Juan Carlos Diaz-Velez, A. Sandoval, Mora Durocher, D. Garcia, C. Alvarez, E. De la Fuente, F. Werner, D. Avila Rojas, F. Serna, J. R. Angeles Camacho, Kwok Lung Fan, Petra Hüntemeyer, J. C. Arteaga-Velázquez, Michael Schneider, R. Diaz Hernandez, S. Hernandez, Nicola Omodei, Arturo Iriarte, K. Tollefson, B. Hona, Gilgamesh Luis-Raya, C. De León, V. Baghmanyan, E. Moreno, C. Brisbois, Umberto Cotti, Maria Magdalena González, Kristi Engel, Nissim Illich Fraija, Sabrina Casanova, Fernando Garfias, A. Zepeda, Harm Schoorlemmer, Pooja Surajbali, J. A. Matthews, E. Ruiz-Velasco, Humberto Ibarguen Salazar, H. Zhou, Fernando Ureña-Mena, Alison Peisker, Z. Ren, Ibrahim Torres, R. Noriega-Papaqui, Filiberto Hueyotl-Zahuantitla, K. P. Arunbabu, Ruben Alfaro, A. L. Longinotti, H. León Vargas, J. P. Harding, Henrike Fleischhack, William H. Lee, L. Olivera-Nieto, O. Martinez, T. Weisgarber, Daniel Rosa-Gonzalez, Miguel Mostafa, Michael DuVernois, Anushka Udara Abeysekara, Roger Blandford, S. Coutiño de León, R. W. Springer, Jose Andres Garcia-Gonzalez, Michael Newbold, Alejandro Lara, K. Malone, E. G. Pérez-Pérez, V. Joshi, J. D. Álvarez, E. Belmont-Moreno, A. J. Smith, Ke Fang, C. D. Rho, T. Capistrán, David Kieda, L. Nellen, F. Salesa Greus, A. Carraminana, Joe Lundeen, R. W. Ellsworth, Jim Hinton, Elijah Willox, J. A. Goodman, Dezhi Huang, Pedro Miranda-Romagnoli, M. U. Nisa, A. Galván-Gámez, Brenda Dingus, J. T. Linnemann, Y. Pérez Araujo, A. Nayerhoda, Segev BenZvi, Gwenael Giacinti, I. Martinez-Castellanos, Andrea Albert, R. Torres-Escobedo, Karen S. Caballero-Mora, Catalina Espinoza, Jesús Martínez-Castro, and H. A. Ayala Solares
Subjects: Physics, Acceleration, Astronomy and Astrophysics, Astrophysics, Ultra-high-energy cosmic ray
Published: 2021
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38. Multiple Galactic Sources with Emission Above 56 TeV Detected by HAWC

Author: J. C. Arteaga-Velázquez, Karen S. Caballero-Mora, S. Hernandez, A. Carraminana, Maria Magdalena González, Z. Ren, Filiberto Hueyotl-Zahuantitla, Dezhi Huang, Catalina Espinoza, J. Pretz, Joe Lundeen, Miguel Mostafa, Gilgamesh Luis-Raya, John Matthews, Jesús Martínez-Castro, R. W. Ellsworth, H. A. Ayala Solares, J. A. Morales-Soto, Tomás Capistrán, S. S. Marinelli, C. Brisbois, Haocheng Zhang, V. Joshi, Luis Villaseñor, Ruben Alfaro, C. Rivière, R. W. Springer, Ibrahim Torres, Anushka Udara Abeysekara, Fernando Garfias, Michael Newbold, Daniel Rosa-Gonzalez, E. G. Pérez-Pérez, A. Nayerhoda, Thomas Weisgarber, A. Galván-Gámez, S. Coutiño de León, E. Ruiz-Velasco, S. Kaufmann, Hao Zhou, Segev BenZvi, J. A. Goodman, Alejandro Lara, Chang Dong Rho, Alison Peisker, Pedro Miranda-Romagnoli, H. León Vargas, E. Moreno, Kristi Engel, Umberto Cotti, Ernesto Belmont-Moreno, K. P. Arunbabu, David Kieda, Jim Hinton, J C Díaz-Vélez, Brenda Dingus, R. López-Coto, Andrea Albert, Henrike Fleischhack, Sabrina Casanova, A. Sandoval, Jorge Cotzomi, R. Torres-Escobedo, Arturo Iriarte, Anna Lia Longinotti, Kelly Malone, Meghan Tanner, Michael Schneider, Harm Schoorlemmer, E. Tabachnick, Nissim Illich Fraija, R. Noriega-Papaqui, M. U. Nisa, O. Tibolla, J. T. Linnemann, William H. Lee, D. Garcia, J. P. Harding, Binita Hona, O. Martinez, I. Martinez-Castellanos, K. Tollefson, Pooja Surajbali, Gus Sinnis, J. Wood, J. R. Angeles Camacho, T. Yapici, H. Martínez-Huerta, Jose Andres Garcia-Gonzalez, Petra Hüntemeyer, E. De la Fuente, D. Avila Rojas, A. J. Smith, L. Nellen, V. Baghmanyan, C. De León, Armelle Jardin-Blicq, Michael DuVernois, F. Salesa Greus, M. J. F. Rosenberg, Simone Dichiara, and HAWC Collaboration
Subjects: Physics, HAWC - Abteilung Hinton, High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, Astrophysics::Instrumentation and Methods for Astrophysics, General Physics and Astronomy, Flux, Astronomy, FOS: Physical sciences, ASTROFÍSICA, Effects of high altitude on humans, 01 natural sciences, Spectral line, Observatory, 0103 physical sciences, 010306 general physics, Astrophysics - High Energy Astrophysical Phenomena, Cherenkov radiation
Abstract: We present the first catalog of gamma-ray sources emitting above 56 and 100 TeV with data from the High Altitude Water Cherenkov (HAWC) Observatory, a wide field-of-view observatory capable of detecting gamma rays up to a few hundred TeV. Nine sources are observed above 56 TeV, all of which are likely Galactic in origin. Three sources continue emitting past 100 TeV, making this the highest-energy gamma-ray source catalog to date. We report the integral flux of each of these objects. We also report spectra for three highest-energy sources and discuss the possibility that they are PeVatrons., Accepted by Physical Review Letters
Published: 2019

39. Constraints on Lorentz invariance violation from HAWC observations of gamma rays above 100 TeV

Author: Maria Magdalena González, Filiberto Hueyotl-Zahuantitla, J. A. Morales-Soto, Gilgamesh Luis-Raya, C. De León, O. Tibolla, G. B. Yodh, Chang Dong Rho, Michael Newbold, H. Martínez-Huerta, Alison Peisker, Pooja Surajbali, Anna Lia Longinotti, Gus Sinnis, V. Baghmanyan, Ibrahim Torres, A. Nayerhoda, A. Sandoval, K. Tollefson, J. R. Angeles Camacho, A. Zepeda, A. J. Smith, Hao Zhou, Henrike Fleischhack, F. Salesa Greus, E. Moreno, Ernesto Belmont-Moreno, A. Carraminana, M. J. F. Rosenberg, Michael Schneider, Joe Lundeen, L. Nellen, S. Hernandez, Humberto Ibarguen Salazar, K. P. Arunbabu, R. López-Coto, Petra Hüntemeyer, Binita Hona, Nicola Omodei, S. Coutiño de León, R. W. Ellsworth, Chad Brisbois, Michael DuVernois, Arturo Iriarte, D. Garcia, Kristi Engel, Alejandro Lara, Andrea Albert, C. Alvarez, K. Malone, R. Torres-Escobedo, M. U. Nisa, V. Joshi, Segev BenZvi, C. Rivière, Meghan Tanner, John Matthews, Harm Schoorlemmer, E. Tabachnick, Pedro Miranda-Romagnoli, R. Noriega-Papaqui, J. A. Goodman, E. De la Fuente, D. Avila Rojas, Jose Andres Garcia-Gonzalez, William H. Lee, Nissim Illich Fraija, Dezhi Huang, Karen S. Caballero-Mora, J. P. Harding, Catalina Espinoza, Ruben Alfaro, Tomás Capistrán, Jesús Martínez-Castro, H. A. Ayala Solares, Daniel Rosa-Gonzalez, S. S. Marinelli, R. W. Springer, Jorge Cotzomi, A. Galván-Gámez, E. G. Pérez-Pérez, Brenda Dingus, Juan Carlos Diaz-Velez, I. Martinez-Castellanos, Umberto Cotti, Sabrina Casanova, J. T. Linnemann, Fernando Garfias, Thomas Weisgarber, E. Ruiz-Velasco, H. León Vargas, and J. C. Arteaga-Velázquez
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Photon, Planck energy, Superluminal motion, Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, General Physics and Astronomy, ASTROFÍSICA, Astrophysics, Lorentz covariance, 01 natural sciences, symbols.namesake, Orders of magnitude (time), Observatory, 0103 physical sciences, symbols, 010306 general physics, Astrophysics - High Energy Astrophysical Phenomena, Cherenkov radiation
Abstract: Due to the high energies and long distances to the sources, astrophysical observations provide a unique opportunity to test possible signatures of Lorentz invariance violation (LIV). Superluminal LIV enables the decay of photons at high energy. The High Altitude Water Cherenkov (HAWC) Observatory is among the most sensitive gamma-ray instruments currently operating above 10 TeV. HAWC finds evidence of 100 TeV photon emission from at least four astrophysical sources. These observations exclude, for the strongest of the limits set, the LIV energy scale to $2.2\times10^{31}$ eV, over 1800 times the Planck energy and an improvement of 1 to 2 orders of magnitude over previous limits., Accepted for publication in Physical Review Letters
Published: 2019

40. Measurement of the Crab Nebula Spectrum Past 100 TeV with HAWC

Author: Jorge Cotzomi, Fernando Garfias, Ernesto Belmont-Moreno, S. Kaufmann, Thomas Weisgarber, Jim Hinton, K. Tollefson, E. Ruiz-Velasco, J. A. Morales-Soto, T. Yapici, H. León Vargas, Arturo Iriarte, S. S. Marinelli, R. W. Springer, Simone Dichiara, Harm Schoorlemmer, Umberto Cotti, C. Rivière, Sabrina Casanova, V. Joshi, R. Noriega-Papaqui, E. G. Pérez-Pérez, William H. Lee, Maria Magdalena González, Jose Andres Garcia-Gonzalez, J. C. Arteaga-Velázquez, O. Martinez, S. Hernandez, Andrea Albert, A. Galván-Gámez, V. Baghmanyan, David Kieda, A. Carraminana, J. A. Goodman, M. J. F. Rosenberg, R. Arceo, Brenda Dingus, Joe Lundeen, S. Coutiño de León, Pooja Surajbali, C. Alvarez, C. M. Hui, O. Tibolla, Gus Sinnis, Chad Brisbois, Michael DuVernois, J. Wood, Meghan Tanner, Z. Ren, R. W. Ellsworth, Brian Fick, E. Moreno, Filiberto Hueyotl-Zahuantitla, Alejandro Lara, Hao Zhou, Petra Hüntemeyer, Binita Hona, Karen S. Caballero-Mora, J. D. Álvarez, Catalina Espinoza, J. T. Linnemann, C. De León, Jesús Martínez-Castro, H. A. Ayala Solares, J. Pretz, Nissim Illich Fraija, E. De la Fuente, I. Martinez-Castellanos, D. Avila Rojas, L. Nellen, Armelle Jardin-Blicq, Ruben Alfaro, Ibrahim Torres, Kelly Malone, M. Seglar Arroyo, Alison Peisker, A. Sandoval, A. Nayerhoda, Michael Schneider, J. R. Angeles Camacho, Henrike Fleischhack, F. Salesa Greus, Daniel Rosa-Gonzalez, Segev BenZvi, A. J. Smith, J. P. Harding, Kristi Engel, John Matthews, Juan Carlos Diaz-Velez, Chang Dong Rho, Tomás Capistrán, Humberto Ibarguen Salazar, Mehr Nisa, Michael Newbold, Miguel Mostafa, Anushka Udara Abeysekara, Gilgamesh Luis-Raya, E. Tabachnick, Anna Lia Longinotti, A. Zepeda, K. P. Arunbabu, S. Westerhoff, H. Martínez-Huerta, and Pedro Miranda-Romagnoli
Subjects: HAWC - Abteilung Hinton, High Energy Astrophysical Phenomena (astro-ph.HE), Astroparticle physics, Physics, ISM: individual objects (Crab Nebula), Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, gamma rays: general, acceleration of particles, astroparticle physics, Crab Nebula, Space and Planetary Science, ACELERAÇÃO DE PARTÍCULAS, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract: We present TeV gamma-ray observations of the Crab Nebula, the standard reference source in ground-based gamma-ray astronomy, using data from the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory. In this analysis we use two independent energy-estimation methods that utilize extensive air shower variables such as the core position, shower angle, and shower lateral energy distribution. In contrast, the previously published HAWC energy spectrum roughly estimated the shower energy with only the number of photomultipliers triggered. This new methodology yields a much improved energy resolution over the previous analysis and extends HAWC's ability to accurately measure gamma-ray energies well beyond 100 TeV. The energy spectrum of the Crab Nebula is well fit to a log parabola shape $\left(\frac{dN}{dE} = \phi_0 \left(E/\textrm{7 TeV}\right)^{-\alpha-\beta\ln\left(E/\textrm{7 TeV}\right)}\right)$ with emission up to at least 100 TeV. For the first estimator, a ground parameter that utilizes fits to the lateral distribution function to measure the charge density 40 meters from the shower axis, the best-fit values are $\phi_o$=(2.35$\pm$0.04$^{+0.20}_{-0.21}$)$\times$10$^{-13}$ (TeV cm$^2$ s)$^{-1}$, $\alpha$=2.79$\pm$0.02$^{+0.01}_{-0.03}$, and $\beta$=0.10$\pm$0.01$^{+0.01}_{-0.03}$. For the second estimator, a neural network which uses the charge distribution in annuli around the core and other variables, these values are $\phi_o$=(2.31$\pm$0.02$^{+0.32}_{-0.17}$)$\times$10$^{-13}$ (TeV cm$^2$ s)$^{-1}$, $\alpha$=2.73$\pm$0.02$^{+0.03}_{-0.02}$, and $\beta$=0.06$\pm$0.01$\pm$0.02. The first set of uncertainties are statistical; the second set are systematic. Both methods yield compatible results. These measurements are the highest-energy observation of a gamma-ray source to date., Comment: published in ApJ
Published: 2019

41. Search for Gamma-ray Spectral Lines from Dark Matter Annihilation in Dwarf Galaxies with the High-Altitude Water Cherenkov Observatory

Author: J. A. Morales-Soto, Hao Zhou, K. Malone, C. Alvarez, Ernesto Belmont-Moreno, E. Tabachnick, A. Galván-Gámez, E. De la Fuente, D. Avila Rojas, Tomás Capistrán, C. De León, J. P. Harding, Brenda Dingus, Arturo Iriarte, J. C. Arteaga-Velázquez, O. Martinez, P. Huentemeyer, Andrea Albert, James W. Wood, K. Tollefson, Binita Hona, Juan Carlos Diaz-Velez, Dezhi Huang, Alison Peisker, A. Sandoval, L. Nellen, Michael Schneider, Fernando Garfias, J. T. Linnemann, S. Hernandez, Ibrahim Torres, Nissim Illich Fraija, Thomas Weisgarber, A. Carraminana, Michael DuVernois, R. Noriega-Papaqui, Karen S. Caballero-Mora, Joe Lundeen, H. León Vargas, S. S. Marinelli, C. Brisbois, Catalina Espinoza, I. Martinez-Castellanos, R. W. Springer, Umberto Cotti, Anna Lia Longinotti, E. G. Pérez-Pérez, S. Coutiño de León, Jesús Martínez-Castro, Sabrina Casanova, Kristi Engel, H. A. Ayala Solares, Alejandro Lara, J. A. Goodman, Jose Andres Garcia-Gonzalez, Jorge Cotzomi, F. Salesa Greus, O. Tibolla, Ruben Alfaro, R. Torres-Escobedo, Simone Dichiara, Daniel Rosa-Gonzalez, Chang Dong Rho, John Matthews, Humberto Ibarguen Salazar, Michael Newbold, Miguel Mostafa, V. Joshi, Pedro Miranda-Romagnoli, M. J. F. Rosenberg, A. Zepeda, K. P. Arunbabu, Gilgamesh Luis-Raya, E. Moreno, Maria Magdalena González, Filiberto Hueyotl-Zahuantitla, Segev BenZvi, A. Nayerhoda, and M. U. Nisa
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Annihilation, Astrophysics::High Energy Astrophysical Phenomena, Dark matter, Gamma ray, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Effects of high altitude on humans, Spectral line, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Observatory, Astrophysics - High Energy Astrophysical Phenomena, Cherenkov radiation, Dwarf galaxy
Abstract: Local dwarf spheroidal galaxies (dSphs) are nearby dark-matter dominated systems, making them excellent targets for searching for gamma rays from particle dark matter interactions. If dark matter annihilates or decays directly into two gamma rays (or a gamma ray and a neutral particle), a monochromatic spectral line is created. At TeV energies, no other processes are expected to produce spectral lines, making this a very clean indirect dark matter search channel. With the development of event-by-event energy reconstruction, we can now search for spectral lines with the High Altitude Water Cherenkov (HAWC) Observatory. HAWC is a wide field of view survey instrument located in central Mexico that observes gamma rays from 100 TeV. In this work we present results from a recent search for spectral lines from local, dark matter dominated dwarf galaxies using 1038 days of HAWC data. We also present updated limits on several continuum channels that were reported in a previous publication. Our gamma-ray spectral line limits are the most constraining obtained so far from 20 TeV to 100 TeV., submitted to PRD
Published: 2019
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42. Interplanetary Magnetic Flux Rope Observed at Ground Level by HAWC

Author: J. R. Angeles Camacho, A. Iriarte, Nissim Fraija, James Ryan, J. Martínez-Castro, Luis Villaseñor, J.C. Arteaga-Velázquez, D. Garcia, Tatiana Niembro, E. Moreno, F. Salesa Greus, John Matthews, Luis Preisser, Alejandro Lara, E. G. Pérez-Pérez, J. P. Harding, U. Cotti, K. Malone, T. Capistrán, G. Luis-Raya, A. Carramiñana, D. Avila Rojas, E. De la Fuente, M. Newbold, Amid Nayerhoda, Maria Magdalena González, Teresa Nieves-Chinchilla, B. Hona, Filiberto Hueyotl-Zahuantitla, A. Galván-Gámez, Sabrina Casanova, P. Miranda-Romagnoli, V. Joshi, K. P. Arunbabu, E. Belmont-Moreno, R. Noriega-Papaqui, Jose Andres Garcia-Gonzalez, Ruben Alfaro, I. Torres, Sachiko Akiyama, C. D. Rho, Gerd J. Kunde, D. Huang, J. Cotzomi, Karen S. Caballero-Mora, Catalina Espinoza, H. A. Ayala Solares, C. De León, F. Garfias, R. Diaz Hernandez, Arnulfo Zepeda, A. Sandoval, F. Ureña-Mena, H. León Vargas, Lukas Nellen, R. W. Springer, H. Salazar, C. Alvarez, David Kieda, P. Hüntemeyer, J. A. Goodman, and P. Colin-Farias
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Geomagnetic storm, 010504 meteorology & atmospheric sciences, Turbulence, FOS: Physical sciences, Flux, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Magnetic flux, Physics::Geophysics, Magnetic field, Earth's magnetic field, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Physics::Space Physics, 0103 physical sciences, Coronal mass ejection, Astrophysics::Solar and Stellar Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Interplanetary spaceflight, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences
Abstract: We report the ground-level detection of a Galactic Cosmic-Ray (GCR) flux enhancement lasting $\sim$ 17 hr and associated with the passage of a magnetic flux rope (MFR) over the Earth. The MFR was associated with a slow Coronal Mass Ejection (CME) caused by the eruption of a filament on 2016 October 9. Due to the quiet conditions during the eruption and the lack of interactions during the interplanetary CME transport to the Earth, the associated MFR preserved its configuration and reached the Earth with a strong magnetic field, low density, and a very low turbulence level compared to the local background, thus generating the ideal conditions to redirect and guide GCRs (in the $\sim$ 8 to 60 GV rigidity range) along the magnetic field of the MFR. An important negative $B_Z$ component inside the MFR caused large disturbances in the geomagnetic field and a relatively strong geomagnetic storm. However, these disturbances are not the main factors behind the GCR enhancement. Instead, we found that the major factor was the alignment between the MFR axis and the asymptotic direction of the observer.
Published: 2020
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43. First HAWC Observations of the Sun Constrain Steady TeV Gamma-Ray Emission

Author: E. Moreno, P. Surajbali, Hao Zhou, Annika H. G. Peter, J. Wood, J. P. Harding, O. Enríquez-Rivera, Fernando Garfias, Z. Ren, A. Iriarte, J. C. Arteaga-Velázquez, F. Salesa Greus, J. Martínez-Castro, E. De la Fuente, Joe Lundeen, D. Avila Rojas, Harm Schoorlemmer, A. Albert, S. Westerhoff, M. Seglar Arroyo, Z. Hampel-Arias, Jose Andres Garcia-Gonzalez, M. J. F. Rosenberg, T. Weisgarber, E. G. Pérez-Pérez, S. Dichiara, R. W. Springer, Edna Ruiz-Velasco, Rebecca K. Leane, I. Torres, Petra Hüntemeyer, R. López-Coto, O. Martinez, M. Mostafá, T. Yapici, H. Salazar, Juan Carlos Diaz-Velez, B. Hona, S. Kaufmann, L. Nellen, I. Martinez-Castellanos, Cristobal M. Espinoza, Kenny C. Y. Ng, C. D. Rho, N. Fraija, M. M. González, T. Capistrán, Filiberto Hueyotl-Zahuantitla, E. Belmont-Moreno, A. Nayerhoda, John F. Beacom, Brenda Dingus, Michael Schneider, I. G. Wisher, S. Coutiño de León, Henrike Fleischhack, C. Alvarez, Segev BenZvi, J. Cotzomi, A. Carramiñana, Sabrina Casanova, O. Tibolla, S. S. Marinelli, G. Sinnis, A. Sandoval, T. Linden, Chad Brisbois, Michael DuVernois, V. Joshi, R. Arceo, P. Miranda-Romagnoli, M. Newbold, Karen S. Caballero-Mora, H. A. Ayala Solares, A. Jardin-Blicq, Kristi Engel, M. Castillo, H. León Vargas, Mehr Nisa, I. Taboada, Bei Zhou, K. Tollefson, C. De León, Jdr Alvarez, C. Rivière, A. Zepeda, Jennifer Pretz, Daniel Rosa-Gonzalez, R. Alfaro, A. J. Smith, R. Noriega-Papaqui, G. Luis-Raya, S. Hernandez, L. Villaseñor, J. A. Goodman, K. Malone, and HAWC Collaboration
Subjects: Solar minimum, Astrophysics::High Energy Astrophysical Phenomena, Hadron, Flux, FOS: Physical sciences, Cosmic ray, Astrophysics, 7. Clean energy, 01 natural sciences, Atmosphere, High Energy Physics - Phenomenology (hep-ph), Observatory, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Cherenkov radiation, Solar and Stellar Astrophysics (astro-ph.SR), Physics, High Energy Astrophysical Phenomena (astro-ph.HE), HAWC - Abteilung Hinton, 010308 nuclear & particles physics, Gamma ray, High Energy Physics - Phenomenology, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: Steady gamma-ray emission up to at least 200 GeV has been detected from the solar disk in the Fermi-LAT data, with the brightest, hardest emission occurring during solar minimum. The likely cause is hadronic cosmic rays undergoing collisions in the Sun's atmosphere after being redirected from ingoing to outgoing in magnetic fields, though the exact mechanism is not understood. An important new test of the gamma-ray production mechanism will follow from observations at higher energies. Only the High Altitude Water Cherenkov (HAWC) Observatory has the required sensitivity to effectively probe the Sun in the TeV range. Using three years of HAWC data from November 2014 to December 2017, just prior to the solar minimum, we search for 1--100 TeV gamma rays from the solar disk. No evidence of a signal is observed, and we set strong upper limits on the flux at a few $10^{-12}$ TeV$^{-1}$ cm$^{-2}$ s$^{-1}$ at 1 TeV. Our limit, which is the most constraining result on TeV gamma rays from the Sun, is $\sim10\%$ of the theoretical maximum flux (based on a model where all incoming cosmic rays produce outgoing photons), which in turn is comparable to the Fermi-LAT data near 100 GeV. The prospects for a first TeV detection of the Sun by HAWC are especially high during solar minimum, which began in early 2018., Comment: 14 pages, 6 figures. See also companion paper 1808.05624. Accepted for publication in Physical Review D
Published: 2018

44. Very-high-energy particle acceleration powered by the jets of the microquasar SS 433

Author: A U, Abeysekara, A, Albert, R, Alfaro, C, Alvarez, J D, Álvarez, R, Arceo, J C, Arteaga-Velázquez, D, Avila Rojas, H A, Ayala Solares, E, Belmont-Moreno, S Y, BenZvi, C, Brisbois, K S, Caballero-Mora, T, Capistrán, A, Carramiñana, S, Casanova, M, Castillo, U, Cotti, J, Cotzomi, S, Coutiño de León, C, De León, E, De la Fuente, J C, Díaz-Vélez, S, Dichiara, B L, Dingus, M A, DuVernois, R W, Ellsworth, K, Engel, C, Espinoza, K, Fang, H, Fleischhack, N, Fraija, A, Galván-Gámez, J A, García-González, F, Garfias, A, González-Muñoz, M M, González, J A, Goodman, Z, Hampel-Arias, J P, Harding, S, Hernandez, J, Hinton, B, Hona, F, Hueyotl-Zahuantitla, C M, Hui, P, Hüntemeyer, A, Iriarte, A, Jardin-Blicq, V, Joshi, S, Kaufmann, P, Kar, G J, Kunde, R J, Lauer, W H, Lee, H, León Vargas, H, Li, J T, Linnemann, A L, Longinotti, G, Luis-Raya, R, López-Coto, K, Malone, S S, Marinelli, O, Martinez, I, Martinez-Castellanos, 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, J, Pretz, E G, Pérez-Pérez, Z, Ren, C D, Rho, C, Rivière, D, Rosa-González, M, Rosenberg, E, Ruiz-Velasco, F, Salesa Greus, A, Sandoval, M, Schneider, H, Schoorlemmer, M, Seglar Arroyo, G, Sinnis, A J, Smith, R W, Springer, P, Surajbali, I, Taboada, O, Tibolla, K, Tollefson, I, Torres, G, Vianello, L, Villaseñor, T, Weisgarber, F, Werner, S, Westerhoff, J, Wood, T, Yapici, G, Yodh, A, Zepeda, H, Zhang, and H, Zhou
Abstract: SS 433 is a binary system containing a supergiant star that is overflowing its Roche lobe with matter accreting onto a compact object (either a black hole or neutron star)
Published: 2018

45. Constraining the p¯/p ratio in TeV cosmic rays with observations of the Moon shadow by HAWC

Author: Ernesto Belmont-Moreno, John N. Wood, E. G. Pérez-Pérez, Kelly Malone, R. W. Springer, J. C. Arteaga-Velázquez, M. J. Martínez González, Arturo Iriarte, A. J. S. Smith, S. Hernandez, Ruben Alfaro, E. Moreno, Edna Ruiz-Velasco, Pooja Surajbali, Andrés Sandoval, O. Martinez, Daniel Rosa-Gonzalez, C. M. Hui, Simone Dichiara, A. González Muñoz, F. Salesa Greus, C. De León, Tomás Capistrán, L. Villaseñor, Anushka Udara Abeysekara, Thomas Weisgarber, Nissim Illich Fraija, J. A. Matthews, G. Sinnis, M. Seglar Arroyo, O. Enríquez-Rivera, Pedro Miranda-Romagnoli, James E. Braun, H. León Vargas, Ibrahim Torres, Petra Hüntemeyer, R. López-Coto, Michael Schneider, S. Westerhoff, Armelle Jardin-Blicq, Chang Dong Rho, Henrike Fleischhack, C. Alvarez, Omar Tibolla, Binita Hona, Jorge Cotzomi, Jdr Alvarez, S. Kaufmann, E. De la Fuente, A. Albert, D. Avila Rojas, R. Arceo, G. B. Yodh, T. Yapici, Z. Hampel-Arias, L. Nellen, Chad Brisbois, S. Coutiño de León, M. J. F. Rosenberg, Michael DuVernois, M. Castillo, R. Diaz Hernandez, J. P. Harding, Jose Andres Garcia-Gonzalez, Gilgamesh Luis-Raya, Alejandro Lara, J. Pretz, Anna Lia Longinotti, Kristi Engel, H. Martínez-Huerta, Hongyan Zhou, Umberto Cotti, Z. Ren, Filiberto Hueyotl-Zahuantitla, I. Taboada, Sabrina Casanova, V. Joshi, A. Zepeda, Harm Schoorlemmer, Miguel Mostafa, Michael Newbold, Karen S. Caballero-Mora, Jesús Martínez-Castro, H. A. Ayala Solares, Colas Rivière, R. Pelayo, A. Carraminana, R. Noriega-Papaqui, William H. Lee, S. Y. BenZvi, R. W. Ellsworth, M. U. Nisa, J. T. Linnemann, R. Luna-Garcia, I. Martinez-Castellanos, A. Galván-Gámez, Brenda Dingus, and S. S. Marinelli
Subjects: Physics, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Cosmic ray, Astrophysics, 01 natural sciences, Magnetic field, Earth's magnetic field, Deflection (physics), Observatory, Antiproton, Physics::Space Physics, 0103 physical sciences, 010306 general physics, Cherenkov radiation
Abstract: An indirect measurement of the antiproton flux in cosmic rays is possible as the particles undergo deflection by the geomagnetic field. This effect can be measured by studying the deficit in the flux, or shadow, created by the Moon as it absorbs cosmic rays that are headed towards the Earth. The shadow is displaced from the actual position of the Moon due to geomagnetic deflection, which is a function of the energy and charge of the cosmic rays. The displacement provides a natural tool for momentum/charge discrimination that can be used to study the composition of cosmic rays. Using 33 months of data comprising more than 80 billion cosmic rays measured by the High Altitude Water Cherenkov (HAWC) observatory, we have analyzed the Moon shadow to search for TeV antiprotons in cosmic rays. We present our first upper limits on the $\bar{p}/p$ fraction, which in the absence of any direct measurements, provide the tightest available constraints of $\sim1\%$ on the antiproton fraction for energies between 1 and 10 TeV.
Published: 2018
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46. A Search for Dark Matter in the Galactic Halo with HAWC

Author: E. Moreno, D. W. Fiorino, Andrea Albert, J. Pretz, Benjamin R. Safdi, Dirk Lennarz, Luis Villaseñor, R. Arceo, Chad Brisbois, Michael DuVernois, R. Luna-Garcia, A. Carraminana, Giacomo Vianello, J. A. Goodman, A. Zepeda, J. P. Harding, J. T. Linnemann, Maria Magdalena González, R. J. Lauer, A. Becerril, Fernando Garfias, Thomas Weisgarber, Juan Carlos Diaz-Velez, Karen S. Caballero-Mora, Ruben Alfaro, E. Ruiz-Velasco, Jesús Martínez-Castro, A. Hernandez-Almada, Tomás Capistrán, Nicholas L. Rodd, H. A. Ayala Solares, O. Enríquez-Rivera, I. Martinez-Castellanos, Ernesto Belmont-Moreno, Daniel Rosa-Gonzalez, Z. Ren, Filiberto Hueyotl-Zahuantitla, Miguel Mostafa, Pedro Miranda-Romagnoli, F. Salesa Greus, H. León Vargas, John Matthews, Anushka Udara Abeysekara, Umberto Cotti, C. De León, I. Taboada, Sabrina Casanova, V. Joshi, Segev BenZvi, Michael Newbold, P. W. Younk, E. De la Fuente, D. Avila Rojas, Ibrahim Torres, Jorge Cotzomi, Abel Bernal, J. C. Arteaga-Velázquez, O. Tibolla, Henrike Fleischhack, G. B. Yodh, Kelly Malone, J. D. Álvarez, Kristi Engel, A. Sandoval, Armelle Jardin-Blicq, M. Castillo, R. Noriega-Papaqui, S. Hernandez, M. J. F. Rosenberg, Michael Schneider, I. G. Wisher, A. González Muñoz, William H. Lee, Brenda Dingus, Sarah Kaufmann, James W. Wood, Arturo Iriarte, Gilgamesh Luis-Raya, Kirsten Tollefson, T. Yapici, Rodrigo Pelayo, O. Martinez, S. Westerhoff, Hao Zhou, Petra Hüntemeyer, T. N. Ukwatta, Pooja Surajbali, Gus Sinnis, Jose Andres Garcia-Gonzalez, Nissim Illich Fraija, S. S. Marinelli, R. W. Springer, E. G. Pérez-Pérez, A. J. Smith, C. Alvarez, L. Nellen, Z. Hampel-Arias, R. Diaz Hernandez, Ruben Lopez-Coto, Anna Lia Longinotti, Humberto Ibarguen Salazar, Mehr Nisa, Chang Dong Rho, and HAWC Collaboartion
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::High Energy Astrophysical Phenomena, Dark matter, Cosmic background radiation, FOS: Physical sciences, Cosmic ray, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Galactic halo, High Energy Physics - Phenomenology (hep-ph), Observatory, 0103 physical sciences, 010303 astronomy & astrophysics, Cherenkov radiation, Astrophysics::Galaxy Astrophysics, Physics, HAWC - Abteilung Hinton, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, High Energy Physics - Phenomenology, Navarro–Frenk–White profile, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a wide field-of-view observatory sensitive to 500 GeV - 100 TeV gamma rays and cosmic rays. With its observations over 2/3 of the sky every day, the HAWC observatory is sensitive to a wide variety of astrophysical sources, including possible gamma rays from dark matter. Dark matter annihilation and decay in the Milky Way Galaxy should produce gamma-ray signals across many degrees on the sky. The HAWC instantaneous field-of-view of 2 sr enables observations of extended regions on the sky, such as those from dark matter in the Galactic halo. Here we show limits on the dark matter annihilation cross-section and decay lifetime from HAWC observations of the Galactic halo with 15 months of data. These are some of the most robust limits on TeV and PeV dark matter, largely insensitive to the dark matter morphology. These limits begin to constrain models in which PeV IceCube neutrinos are explained by dark matter which primarily decays into hadrons., 24 pages, 11 figures
Published: 2017

47. Search for very-high-energy emission from Gamma-ray Bursts using the first 18 months of data from the HAWC Gamma-ray Observatory

Author: Ignacio Taboada, Daniel Rosa-Gonzalez, U. Cotti, I. Torres, Kristi Engel, C. De León, A. J. Smith, T. Capistrán, S. S. Marinelli, Michael DuVernois, G. Sinnis, Pooja Surajbali, Armelle Jardin-Blicq, K. Malone, Harm Schoorlemmer, C. Rivière, J. D. Álvarez, Edna Ruiz-Velasco, M. Castillo, A. Hernandez-Almada, Fernando Garfias, P. W. Younk, Thomas Weisgarber, A. Zepeda, S. Coutiño Deleón, D. W. Fiorino, Dirk Lennarz, R. Noriega-Papaqui, J. A. Goodman, J. P. Harding, Ernesto Belmont-Moreno, N. Bautista-Elivar, A. Carraminana, A. S. Barber, H. León Vargas, J. Martínez-Castro, F. Salesa Greus, James W. Wood, P. Hüntemeyer, A. Becerril, C. M. Hui, Z. Hampel-Arias, A. Sandoval, Lukas Nellen, T. N. Ukwatta, S. Hernandez, Hao Zhou, Rodrigo Pelayo, R. Arceo, S. Westerhoff, Binita Hona, A. González Muñoz, Chad Brisbois, N. Fraija, A. Iriarte, J. Pretz, Maria Magdalena González, Juan Carlos Diaz-Velez, R. J. Lauer, Abel Bernal, Jose Andres Garcia-Gonzalez, O. Martinez, R. W. Ellsworth, T. Yapici, Michael Schneider, Giacomo Vianello, M. J. F. Rosenberg, Sarah Kaufmann, M. Mostafá, Z. Ren, Tyce DeYoung, Humberto Ibarguen Salazar, G. Luis Raya, Brenda Dingus, Kirsten Tollefson, H. Martínez-Huerta, J. Braun, E. Moreno, R. Luna-Garcia, Karen S. Caballero-Mora, W. H. Lee, I. Martinez-Castellanos, H. A. Ayala Solares, O. Tibolla, J. Cotzomi, R. W. Springer, J.C. Arteaga-Velázquez, E. G. Pérez-Pérez, C. Alvarez, David Kieda, Pedro Miranda-Romagnoli, Chang Dong Rho, J. A. Matthews, M. Newbold, R. Diaz Hernandez, Segev BenZvi, R. Alfaro, Ruben Lopez-Coto, J. T. Linnemann, Anna Lia Longinotti, Sabrina Casanova, V. Joshi, E. De la Fuente, D. Avila Rojas, and M. Gerhardt
Subjects: HAWC - Abteilung Hinton, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Attenuation, Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Synchrotron, Redshift, law.invention, Space and Planetary Science, law, Observatory, 0103 physical sciences, Satellite, Astrophysics - High Energy Astrophysical Phenomena, Gamma-ray burst, 010303 astronomy & astrophysics, Cherenkov radiation
Abstract: The High Altitude Water Cherenkov (HAWC) Gamma-ray Observatory is an extensive air shower detector operating in central Mexico, which has recently completed its first two years of full operations. If for a burst like GRB 130427A at a redshift of 0.34 and a high-energy component following a power law with index -1.66, the high-energy component is extended to higher energies with no cut-off other than from extragalactic background light attenuation, HAWC would observe gamma rays with a peak energy of $\sim$300 GeV. This paper reports the results of HAWC observations of 64 gamma-ray bursts (GRBs) detected by $\mathit{Swift}$ and $\mathit{Fermi}$, including three GRBs that were also detected by the Large Area Telescope ($\mathit{Fermi}$-LAT). An ON/OFF analysis method is employed, searching on the time scale given by the observed light curve at keV-MeV energies and also on extended time scales. For all GRBs and time scales, no statistically significant excess of counts is found and upper limits on the number of gamma rays and the gamma-ray flux are calculated. GRB 170206A, the third brightest short GRB detected by the Gamma-ray Burst Monitor on board the $\mathit{Fermi}$ satellite ($\mathit{Fermi}$-GBM) and also detected by the LAT, occurred very close to zenith. The LAT measurements can neither exclude the presence of a synchrotron self-Compton (SSC) component nor constrain its spectrum. Instead, the HAWC upper limits constrain the expected cut-off in an additional high-energy component to be less than $100~\rm{GeV}$ for reasonable assumptions about the energetics and redshift of the burst., Comment: 19 pages, 6 figures, published in ApJ
Published: 2017
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48. Dark Matter Limits From Dwarf Spheroidal Galaxies with The HAWC Gamma-Ray Observatory

Author: A. Albert, R. Alfaro, C. Alvarez, J. D. Álvarez, R. Arceo, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A. Ayala Solares, N. Bautista-Elivar, A. Becerril, E. Belmont-Moreno, S. Y. BenZvi, A. Bernal, J. Braun, C. Brisbois, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, M. Castillo, U. Cotti, J. Cotzomi, S. Coutiño de León, C. De León, E. De la Fuente, R. Diaz Hernandez, B. L. Dingus, M. A. DuVernois, J. C. Díaz-Vélez, R. W. Ellsworth, K. Engel, D. W. Fiorino, N. Fraija, J. A. García-González, F. Garfias, M. M. González, J. A. Goodman, Z. Hampel-Arias, J. P. Harding, S. Hernandez, A. Hernandez-Almada, B. Hona, P. Hüntemeyer, A. Iriarte, A. Jardin-Blicq, V. Joshi, S. Kaufmann, D. Kieda, R. J. Lauer, D. Lennarz, H. León Vargas, J. T. Linnemann, A. L. Longinotti, M. Longo Proper, G. Luis Raya, R. Luna-García, R. López-Coto, K. Malone, S. S. Marinelli, I. Martinez-Castellanos, J. Martínez-Castro, H. Martínez-Huerta, J. A. Matthews, P. Miranda-Romagnoli, E. Moreno, M. Mostafá, L. Nellen, M. Newbold, M. U. Nisa, R. Noriega-Papaqui, R. Pelayo, J. Pretz, E. G. Pérez-Pérez, Z. Ren, C. D. Rho, C. Rivière, D. Rosa-González, M. Rosenberg, E. Ruiz-Velasco, F. Salesa Greus, A. Sandoval, M. Schneider, H. Schoorlemmer, G. Sinnis, A. J. Smith, R. W. Springer, P. Surajbali, I. Taboada, O. Tibolla, K. Tollefson, I. Torres, G. Vianello, T. Weisgarber, S. Westerhoff, J. Wood, T. Yapici, P. W. Younk, and H. Zhou
Subjects: Physics, HAWC - Abteilung Hinton, High Energy Astrophysical Phenomena (astro-ph.HE), Annihilation, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Dark matter, Gamma ray, FOS: Physical sciences, Astronomy and Astrophysics, Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Wide field, Galaxy, High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Space and Planetary Science, Observatory, 0103 physical sciences, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Cherenkov radiation
Abstract: The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a wide field of view observatory sensitive to 500 GeV - 100 TeV gamma rays and cosmic rays. It can also perform diverse indirect searches for dark matter (DM) annihilation and decay. Among the most promising targets for the indirect detection of dark matter are dwarf spheroidal galaxies. These objects are expected to have few astrophysical sources of gamma rays but high dark matter content, making them ideal candidates for an indirect dark matter detection with gamma rays. Here we present individual limits on the annihilation cross section and decay lifetime for 15 dwarf spheroidal galaxies within the HAWC field-of-view, as well as their combined limit. These are the first limits on the annihilation cross section and decay lifetime using data collected with HAWC., Comment: 18 pages, 6 figures, 2 tables
Published: 2017
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49. Searching for dark matter sub-structure with HAWC

Author: E. Moreno, I. Torres, R. W. Springer, Segev BenZvi, H. León Vargas, Maria Magdalena González, H. Salazar, C. Alvarez, S. S. Marinelli, J. P. Harding, A. Iriarte, I. Martinez-Castellanos, John Matthews, S. Dichiara, Filiberto Hueyotl-Zahuantitla, Karen S. Caballero-Mora, H. Fleischhack, J. D. Álvarez, Oscar Martinez, Arnulfo Zepeda, Nissim Fraija, J. C. Díaz-Vélez, Marvin Oliver Schneider, Carmen Espinoza, Ruben Alfaro, H. A. Ayala Solares, R. Noriega-Papaqui, K. Malone, Daniel Rosa-Gonzalez, Giacomo Vianello, R. Arceo, E. G. Pérez-Pérez, Joe Lundeen, Andrea Albert, K. Tollefson, A. Sandoval, J. Martínez-Castro, G. Luis-Raya, M. Newbold, W. H. Lee, T. Weisgarber, Lukas Nellen, J. Cotzomi, Hao Zhou, Anushka Udara Abeysekara, B. Hona, P. Hüntemeyer, C. D. Rho, C. Brisbois, James W. Wood, A. J. Smith, A. L. Longinotti, P. Miranda-Romagnoli, M. J. F. Rosenberg, T. Yapici, M. Mostafá, Jose Andres Garcia-Gonzalez, S. Coutiño de León, Brenda Dingus, Z. Ren, K. Engel, F. Salesa Greus, Alejandro Lara, E. Belmont-Moreno, C. Rivière, Amid Nayerhoda, G. Sinnis, J. T. Linnemann, Michael DuVernois, A. Carramiñana, J. A. Goodman, D. Avila Rojas, A. Galván-Gámez, Sabrina Casanova, E. De la Fuente, J.C. Arteaga-Velázquez, C. De León, and M. U. Nisa
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Milky Way, media_common.quotation_subject, Dark matter, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Galaxy, Observatory, Sky, 0103 physical sciences, Halo, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics, Cherenkov radiation, Dwarf galaxy, media_common
Abstract: Simulations of dark matter show a discrepancy between the expected number of Galactic dark matter sub-halos and how many have been optically observed. Some of these unseen satellites may exist as dark dwarf galaxies: sub-halos like dwarf galaxies with no luminous counterpart. Assuming WIMP dark matter, it may be possible to detect these unseen sub-halos from gamma-ray signals originating from dark matter annihilation. The High Altitude Water Cherenkov Observatory (HAWC) is a very high energy (500 GeV to 100 TeV) gamma ray detector with a wide field-of-view and near continuous duty cycle, making HAWC ideal for unbiased sky surveys. We perform such a search for gamma ray signals from dark dwarfs in the Milky Way halo. We perform a targeted search of HAWC gamma-ray sources which have no known association with lower-energy counterparts, based on an unbiased search of the entire sky. With no sources found to strongly prefer dark matter models, we calculate the ability of HAWC to observe dark dwarfs. We also compute the HAWC sensitivity to potential future detections for a given model of dark matter substructure., Comment: 20 pages, 10 figures. submitted to JCAP
Published: 2019
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50. Erratum: Search for dark matter gamma-ray emission from the Andromeda Galaxy with the High-Altitude Water Cherenkov Observatory

Author: A Albert, R Alfaro, C Alvarez, J.D Álvarez, R Arceo, J.C Arteaga-Velázquez, D. Avila Rojas, H.A. Ayala Solares, A Becerril, E Belmont-Moreno, S.Y BenZvi, A Bernal, C Brisbois, K.S Caballero-Mora, T Capistrán, A Carramiñana, S Casanova, M Castillo, U Cotti, J Cotzomi, S. Coutiño de León, C. De León, S Dichiara, B.L Dingus, M.A DuVernois, J.C Díaz-Vélez, C Eckner, K Engel, O Enríquez-Rivera, C Espinoza, D.W Fiorino, N Fraija, E. De la Fuente, A Galván-Gámez, J.A García-González, F Garfias, A. González Muñoz, M.M González, J.A Goodman, Z Hampel-Arias, J.P Harding, S Hernandez, A Hernandez-Almada, B Hona, P Hüntemeyer, A Iriarte, A Jardin-Blicq, V Joshi, S Kaufmann, G.J Kunde, D Lennarz, H. León Vargas, J.T Linnemann, A.L Longinotti, G. Luis Raya, R Luna-García, K Malone, S.S Marinelli, O Martinez, J Martínez-Castro, H Martínez-Huerta, J.A Matthews, P Miranda-Romagnoli, E Moreno, M Mostafá, A Nayerhoda, L Nellen, M Newbold, M.U Nisa, R Noriega-Papaqui, R Pelayo, J Pretz, E.G Pérez-Pérez, Z Ren, C.D Rho, C Riviére, D Rosa-González, M Rosenberg, E Ruiz-Velasco, H Salazar, F. Salesa Greus, A Sandoval, M Schneider, M. Seglar Arroyo, G Sinnis, A.J Smith, R.W Springer, P Surajbali, I Taboada, O Tibolla, K Tollefson, I Torres, T.N Ukwatta, L Villaseñor, T Weisgarber, S Westerhoff, J Wood, T Yapici, G Zaharijas, A Zepeda, and H Zhou
Subjects: Physics, Andromeda Galaxy, Observatory, Dark matter, Gamma ray, Astronomy, Astronomy and Astrophysics, Effects of high altitude on humans, Cherenkov radiation
Published: 2019
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