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1. HAWC Contributions to the 36th International Cosmic Ray Conference (ICRC2019)

Author: Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Álvarez, J. D., Camacho, J. R. Angeles, Arteaga-Velázquez, J. C., Arunbabu, K. P., Rojas, D. Avila, Solares, H. A. Ayala, Baghmanyan, V., Barber, A. S., Gonzalez, J. Becerra, Belmont-Moreno, E., BenZvi, S. Y., Berley, D., Braun, J., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Cotti12, U., Cotzomi, J., de León, S. Coutiño, De la Fuente, E., de León, C., Hernandez, R. Diaz, Diaz-Cruz, L., Díaz-Vélez, J. C., Dichiara, S., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Engel, K., Enríquez-Rivera, O., Espinoza, C., Alonso, M. Fernández, Fick, B., Fiorino, D. W., Fleischhack, H., Fraija, N., Galván-Gámez, A., García-González, J. A., Garcia-Luna, J. L., Garfias, F., Giacinti, G., González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hinton, J., Hona, B., Huang, D., Hueyotl-Zahuantitla, F., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kieda, D., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., López-Coto, R., Luis-Raya, G., Lundeen, J., Malone, K., Marandon, V., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A. J., McEnery, J., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Peisker, A., Araujo, Y. Pérez, Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Ryan, J., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Arroyo, M. Seglar, Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Tabachnick, E., Taboada, I., Tanner, M., Tollefson, K., Torres, I., Torres-Escobedo, R., Ukwatta, T. N., Vianello, G., Villaseñor, L., Weisgarber, T., Werner, F., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Yodh, G. B., Younk, P. W., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract: List of proceedings from the HAWC Collaboration presented at the 36th International Cosmic Ray Conference, 24 July - 1 August 2019, Madison, Wisconsin, USA., Comment: List of proceedings from the HAWC Collaboration presented at ICRC2019. Corrected typos in the index of the previous version. Follow the "HTML" link to access the list
Published: 2019

2. MAGIC and Fermi-LAT gamma-ray results on unassociated HAWC sources

Author: Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Arcaro, C., Baack, D., Babić, A., Banerjee, B., Bangale, P., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Berse, R. Ch., Berti, A., Bhattacharyya, W., Biland, A., Blanch, O., Bonnoli, G., Carosi, R., Carosi, A., Ceribella, G., Chatterjee, A., Colak, S. M., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Cumani, P., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Di Pierro, F., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Ramazani, V. Fallah, Fernández-Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Fruck, C., Galindo, D., López, R. J. García, Garczarczyk, M., Gaug, M., Giammaria, P., Godinović, N., Gora, D., Guberman, D., Hadasch, D., Hahn, A., Hassan, T., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Ishio, K., Konno, Y., Kubo, H., Kushida, J., Kuveždić, D., Lelas, D., Lindfors, E., Lombardi, S., Longo, F., López, M., Maggio, C., Majumdar, P., Makariev, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Masuda, S., Mazin, D., Mielke, K., Minev, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Moreno, V., Moretti, E., Nagayoshi, T., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nievas, Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogués, L., Paiano, S., Palacio, J., Paneque, D., Paoletti, R., Paredes, J. M., Pedaletti, G., Peresano, M., Persic, M., Moroni, P. G. Prada, Prandini, E., Puljak, I., Garcia, J. R., Reichardt, I., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saito, T., Satalecka, K., Schweizer, T., Sitarek, J., Šnidarić, I., Sobczynska, D., Stamerra, A., Strzys, M., Surić, T., Takahashi, M., Takalo, L., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Torres-Albà, N., Treves, A., Tsujimoto, S., Vanzo, G., Acosta, M. Vazquez, Vovk, I., Ward, J. E., Will, M., Zarić, D., Albert, A., Alfaro, R., Alvarez, C., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Bernal, A., Braun, J., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, De León, C., De la Fuente, E., Hernandez, R. Diaz, Dichiara, S., Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Ellsworth, R. W., Engel, K., Enriquez-Rivera, O., Fiorino, D. W., Fleischhack, H., Fraija, N., García-González, J. A., Garfias, F., González-Muñoz, A., González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hueyotl-Zahuantitla, F., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Luna-García, R., López-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Greus, F. Salesa, Sandoval, A., Schneider, M., Arroyo, M. Seglar, Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Vianello, G., Villaseñor, L., Werner, F., Westerhoff, S., Wood, J., Yapici, T., Yodh, G., Zepeda, A., Zhou, H., Álvarez, J. D., Ajello, M., Baldini, L., Barbiellini, G., Berenji, B., Bissaldi, E., Blandford, R. D., Bonino, R., Bottacini, E., Brandt, T. J., Bregeon, J., Bruel, P., Cameron, R. A., Caputo, R., Caraveo, P. A., Castro, D., Cavazzuti, E., Chiaro, G., Ciprini, S., Costantin, D., D'Ammando, F., de Palma, F., Desai, A., Di Lalla, N., Di Mauro, M., Di Venere, L., Favuzzi, C., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Giglietto, N., Giordano, F., Giroletti, M., Glanzman, T., Green, D., Grenier, I. A., Guiriec, S., Harding, A. K., Hays, E., Hewitt, J. W., Horan, D., Jóhannesson, G., Kuss, M., Larsson, S., Liodakis, I., Loparco, F., Lubrano, P., Magill, J. D., Maldera, S., Manfreda, A., Mazziotta, M. N., Mereu, I., Michelson, P. F., Mizuno, T., Monzani, M. E., Morselli, A., Moskalenko, I. V., Negro, M., Nuss, E., Omodei, N., Orienti, M., Orlando, E., Ormes, J. F., Palatiello, M., Paliya, V. S., Pesce-Rollins, M., Petrosian, V., Piron, F., Porter, T. A., Principe, G., Rainò, S., Rani, B., Razzano, M., Razzaque, S., Reimer, A., Reimer, O., Sgrò, C., Siskind, E. J., Spandre, G., Spinelli, P., Tajima, H., Thayer, J. B., Thompson, D. J., Torres, D. F., Torresi, E., Troja, E., Valverde, J., Wood, K., and Yassine, M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The HAWC Collaboration released the 2HWC catalog 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 catalog motivated follow-up studies by both the MAGIC and Fermi-LAT 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 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 degree extension (at 95% confidence level) and harder spectrum in the GeV than the one extrapolated from HAWC results are required in the case of 2HWC J1852+013*, while a simply minimum extension of 0.16 degrees (at 95% 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., Comment: 12 pages, 3 figures. Accepted for publication in MNRAS
Published: 2019
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3. All-Sky Measurement of the Anisotropy of Cosmic Rays at 10 TeV and Mapping of the Local Interstellar Magnetic Field

Author: HAWC Collaboration, Abeysekara, A. U., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. Avila, Belmont-Moreno, E., BenZvi, S. Y., Brisbois, C., Capistrán, T., Carramiñana, A., Casanova, S., Cotti, U., Cotzomi, J., Díaz-Vélez, J. C., De León, C., De la Fuente, E., Dichiara, S., DuVernois, M. A., Espinoza, C., Fiorino, D. W., Fleischhack, H., Fraija, N., Galván-Gámez, A., García-González, J. A., González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hona, B., Hueyotl-Zahuantitla, F., Iriarte, A., Jardin-Blicq, A., Joshi, V., Lara, A., Vargas, H. León, Luis-Raya, G., Malone, K., Marinelli, S. S., Martínez-Castro, J., Martinez, O., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pérez-Pérez, E. G., Pretz, J., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Sinnis, G., Smith, A. J., Surajbali, P., Taboada, I., Tollefson, K., Torres, I., Villaseño, L., Weisgarber, T., Wood, J., Zepeda, A., Zhou, H., Collaboration, IceCube, Aartsen, M. G., Ackermann, M., Adams, J., Aguilar, J. A., Ahlers, M., Ahrens, M., Altmann, D., Andeen, K., Anderson, T., Ansseau, I., Anton, G., Argüelles, C., Auffenberg, J., Axani, S., Backes, P., Bagherpour, H., Bai, X., Barbano, A., Barron, J. P., Barwick, S. W., Baum, V., Bay, R., Beatty, J. J., Becker, K. -H., Tjus, J. Becker, BenZvi, S., Berley, D., Bernardini, E., Besson, D. Z., Binder, G., Bindig, D., Blaufuss, E., Blot, S., Bohm, C., Börner, M., Bos, F., Böser, S., Botner, O., Bourbeau, E., Bourbeau, J., Bradascio, F., Braun, J., Bretz, H. -P., Bron, S., Brostean-Kaiser, J., Burgman, A., Busse, R. S., Carver, T., Chen, C., Cheung, E., Chirkin, D., Clark, K., Classen, L., Collin, G. H., Conrad, J. M., Coppin, P., Correa, P., Cowen, D. F., Cross, R., Dave, P., Day, M., de André, J. P. A. M., De Clercq, C., DeLaunay, J. J., Dembinski, H., Deoskar, K., De Ridder, S., Desiati, P., de Vries, K. D., de Wasseige, G., de With, M., DeYoung, T., Dujmovic, H., Dunkman, M., Dvorak, E., Eberhardt, B., Ehrhardt, T., Eichmann, B., Eller, P., Evenson, P. A., Fahey, S., Fazely, A. R., Felde, J., Filimonov, K., Finley, C., Franckowiak, A., Friedman, E., Fritz, A., Gaisser, T. K., Gallagher, J., Ganster, E., Garrappa, S., Gerhardt, L., Ghorbani, K., Giang, W., Glauch, T., Glüsenkamp, T., Goldschmidt, A., Gonzalez, J. G., Grant, D., Griffith, Z., Haack, C., Hallgren, A., Halve, L., Halzen, F., Hanson, K., Hebecker, D., Heereman, D., Helbing, K., Hellauer, R., Hickford, S., Hignight, J., Hill, G. C., Hoffman, K. D., Hoffmann, R., Hoinka, T., Hokanson-Fasig, B., Hoshina, K., Huang, F., Huber, M., Hultqvist, K., Hünnefeld, M., Hussain, R., In, S., Iovine, N., Ishihara, A., Jacobi, E., Japaridze, G. S., Jeong, M., Jero, K., Jones, B. J. P., Kalaczynski, P., Kang, W., Kappes, A., Kappesser, D., Karg, T., Karle, A., Katz, U., Kauer, M., Keivani, A., Kelley, J. L., Kheirandish, A., Kim, J., Kintscher, T., Kiryluk, J., Kittler, T., Klein, S. R., Koirala, R., Kolanoski, H., Köpke, L., Kopper, C., Kopper, S., Koskinen, D. J., Kowalski, M., Krings, K., Kroll, M., Krückl, G., Kunwar, S., Kurahashi, N., Kyriacou, A., Labare, M., Lanfranchi, J. L., Larson, M. J., Lauber, F., Leonard, K., Leuermann, M., Liu, Q. R., Lohfink, E., Mariscal, C. J. Lozano, Lu, L., Lünemann, J., Luszczak, W., Madsen, J., Maggi, G., Mahn, K. B. M., Makino, Y., Mancina, S., Mariş, I. C., Maruyama, R., Mase, K., Maunu, R., Meagher, K., Medici, M., Medina, A., Meier, M., Menne, T., Merino, G., Meures, T., Miarecki, S., Micallef, J., Momenté, G., Montaruli, T., Moore, R. W., Moulai, M., Nagai, R., Nahnhauer, R., Nakarmi, P., Naumann, U., Neer, G., Niederhausen, H., Nowicki, S. C., Nygren, D. R., Pollmann, A. Obertacke, Olivas, A., O'Murchadha, A., O'Sullivan, E., Palczewski, T., Pandya, H., Pankova, D. V., Peiffer, P., Heros, C. Pérez de los, Pieloth, D., Pinat, E., Pizzuto, A., Plum, M., Price, P. B., Przybylski, G. T., Raab, C., Raissi, A., Rameez, M., Rauch, L., Rawlins, K., Rea, I. C., Reimann, R., Relethford, B., Renzi, G., Resconi, E., Rhode, W., Richman, M., Robertson, S., Rongen, M., Rott, C., Ruhe, T., Ryckbosch, D., Rysewyk, D., Safa, I., Herrera, S. E. Sanchez, Sandrock, A., Sandroos, J., Santander, M., Sarkar, S., Satalecka, K., Schaufel, M., Schlunder, P., Schmidt, T., Schneider, A., Schneider, J., Schöneberg, S., Schumacher, L., Sclafani, S., Seckel, D., Seunarine, S., Soedingrekso, J., Soldin, D., Song, M., Spiczak, G. M., Spiering, C., Stachurska, J., Stamatikos, M., Stanev, T., Stasik, A., Stein, R., Stettner, J., Steuer, A., Stezelberger, T., Stokstad, R. G., Stößl, A., Strotjohann, N. L., Stuttard, T., Sullivan, G. W., Sutherland, M., Tenholt, F., Ter-Antonyan, S., Terliuk, A., Tilav, S., Tobin, M. N., Tönnis, C., Toscano, S., Tosi, D., Tselengidou, M., Tung, C. F., Turcati, A., Turcotte, R., Turley, C. F., Ty, B., Unger, E., Elorrieta, M. A. Unland, Usner, M., Vandenbroucke, J., Van Driessche, W., van Eijk, D., van Eijndhoven, N., Vanheule, S., van Santen, J., Vraeghe, M., Walck, C., Wallace, A., Wallraff, M., Wandkowsky, N., Wandler, F. D., Watson, T. B., Weaver, C., Weiss, M. J., Weldert, J., Wendt, C., Werthebach, J., Westerhoff, S., Whelan, B. J., Whitehorn, N., Wiebe, K., Wiebusch, C. H., Wille, L., Williams, D. R., Wills, L., Wolf, M., Wood, T. R., Woolsey, E., Woschnagg, K., Wrede, G., Xu, D. L., Xu, X. W., Xu, Y., Yanez, J. P., Yodh, G., Yoshida, S., and Yuan, T.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present the first full-sky analysis of the cosmic ray arrival direction distribution with data collected by the HAWC and IceCube observatories in the Northern and Southern hemispheres at the same median primary particle energy of 10 TeV. The combined sky map and angular power spectrum largely eliminate biases that result from partial sky coverage and holds a key to probe into the propagation properties of TeV cosmic rays through our local interstellar medium and the interaction between the interstellar and heliospheric magnetic fields. From the map we determine the horizontal dipole components of the anisotropy $\delta_{0h} = 9.16 \times 10^{-4}$ and $\delta_{6h} = 7.25 \times 10^{-4}~(\pm0.04 \times 10^{-4})$. In addition, we infer the direction ($229.2\pm 3.5^\circ$ RA , $11.4\pm 3.0^\circ$ Dec.) of the interstellar magnetic field from the boundary between large scale excess and deficit regions from which we estimate the missing corresponding vertical dipole component of the large scale anisotropy to be $\delta_N \sim -3.97 ^{+1.0}_{-2.0} \times 10^{-4}$., Comment: Accepted by The Astrophysical Journal
Published: 2018
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4. Very high energy particle acceleration powered by the jets of the microquasar SS 433

Author: HAWC Collaboration, Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Belmont-Moreno, E., BenZvi, S. Y., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, De León, C., De la Fuente, E., Díaz-Vélez, J. C., Dichiara, S., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Engel, K., Espinoza, C., Fang, K., Fleischhack, H., Fraija, N., Galván-Gámez, A., García-González, J. A., Garfias, F., Muñoz, A. González, González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hinton, J., Hona, B., Hueyotl-Zahuantitla, F., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kar, P., Kunde, G. J., Lauer, R. J., Lee, W. H., Vargas, H. León, Li, H., Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., López-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pérez-Pérez, E. G., Pretz, J., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Arroyo, M. Seglar, Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Vianello, G., Villaseñor, L., Weisgarber, T., Werner, F., Westerhoff, S., Wood, J., Yapici, T., Yodh, G., Zepeda, A., Zhang, H., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
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). Two jets of ionized matter with a bulk velocity of $\sim0.26c$ extend from the binary, perpendicular to the line of sight, and terminate inside W50, a supernova remnant that is being distorted by the jets. SS 433 differs from other microquasars in that the accretion is believed to be super-Eddington, and the luminosity of the system is $\sim10^{40}$ erg s$^{-1}$. The lobes of W50 in which the jets terminate, about 40 pc from the central source, are expected to accelerate charged particles, and indeed radio and X-ray emission consistent with electron synchrotron emission in a magnetic field have been observed. At higher energies (>100 GeV), the particle fluxes of $\gamma$ rays from X-ray hotspots around SS 433 have been reported as flux upper limits. In this energy regime, it has been unclear whether the emission is dominated by electrons that are interacting with photons from the cosmic microwave background through inverse-Compton scattering or by protons interacting with the ambient gas. Here we report TeV $\gamma$-ray observations of the SS 433/W50 system where the lobes are spatially resolved. The TeV emission is localized to structures in the lobes, far from the center of the system where the jets are formed. We have measured photon energies of at least 25 TeV, and these are certainly not Doppler boosted, because of the viewing geometry. We conclude that the emission from radio to TeV energies is consistent with a single population of electrons with energies extending to at least hundreds of TeV in a magnetic field of $\sim16$~micro-Gauss., Comment: Preprint version of Nature paper. Contacts: S. BenZvi, B. Dingus, K. Fang, C.D. Rho , H. Zhang, H. Zhou
Published: 2018
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5. VERITAS and Fermi-LAT observations of new HAWC sources

Author: VERITAS Collaboration, Abeysekara, A. U., Archer, A., Benbow, W., Bird, R., Brose, R., Buchovecky, M., Buckley, J. H., Bugaev, V., Chromey, A. J., Connolly, M. P., Cui, W., Daniel, M. K., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Hutten, M., Hanna, D., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Lin, T. T. Y., McArthur, S., Moriarty, P., Mukherjee, R., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pohl, M., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Sushch, I., Tyler, J., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Williamson, T. J., Zitzer, B., Collaboration, Fermi-LAT, Abdollahi, S., Ajello, M., Baldini, L., Barbiellini, G., Bastieri, D., Bellazzini, R., Berenji, B., Bissaldi, E., Blandford, R. D., Bonino, R., Bottacini, E., Brandt, T. J., Bruel, P., Buehler, R., Cameron, R. A., Caputo, R., Caraveo, P. A., Castro, D., Cavazzuti, E., Charles, E., Chiaro, G., Ciprini, S., Cohen-Tanugi, J., Costantin, D., Cutini, S., D'Ammando, F., de Palma, F., Di Lalla, N., Di Mauro, M., Di Venere, L., Dominguez, A., Favuzzi, C., Fegan, S. J., Franckowiak, A., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Giglietto, N., Giordano, F., Giroletti, M., Green, D., Grenier, I. A., Guillemot, L., Guiriec, S., Hays, E., Hewitt, J. W., Horan, D., Johannesson, G., Kensei, S., Kuss, M., Larsson, S., Latronico, L., Lemoine-Goumard, M., Li, J., Longo, F., Loparco, F., Lovellette, M. N., Lubrano, P., Magill, J. D., Maldera, S., Mazziotta, M. N., McEnery, J. E., Michelson, P. F., Mitthumsiri, W., Mizuno, T., Monzani, M. E., Morselli, A., Moskalenko, I. V., Negro, M., Nuss, E., Ojha, R., Omodei, N., Orienti, M., Orlando, E., Palatiello, M., Paliya, V. S., Paneque, D., Perkins, J. S., Persic, M., Pesce-Rollins, M., Petrosian, V., Piron, F., Porter, T. A., Principe, G., Raino, S., Rando, R., Rani, B., Razzano, M., Razzaque, S., Reimer, A., Reimer, O., Reposeur, T., Sgro, C., Siskind, E. J., Spandre, G., Spinelli, P., Suson, D. J., Tajima, H., Thayer, J. B., Thompson, D. J., Torres, D. F., Tosti, G., Troja, E., Valverde, J., Vianello, G., Vogel, M., Wood, K., Yassine, M., Collaboration, HAWC, Alfaro, R., Alvarez, C., Alvarez, J. D., Arceo, R., Arteaga-Velazquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Bernal, A., Braun, J., Brisbois, C., Caballero-Mora, K. S., Capistran, T., Carraminana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de Leon, S. Coutino, De Leon, C., De la Fuente, E., Dichiara, S., Dingus, B. L., DuVernois, M. A., Diaz-Velez, J. C., Engel, K., Enriquez-Rivera, O., Fiorino, D. W., Fleischhack, H., Fraija, N., Garcia-Gonzalez, J. A., Garfias, F., Munoz, A. Gonzalez, Gonzalez, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hernandez-Almada, A., Hona, B., Hueyotl-Zahuantitla, F., Hui, C. M., Huntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. Leon, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Luna-Garcia, R., Lopez-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martinez-Castro, J., Martinez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafa, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Perez-Perez, E. G., Ren, Z., Rho, C. D., Riviere, C., Rosa-Gonzalez, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Arroyo, M. Seglar, Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Villasenor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Yodh, G., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The HAWC (High Altitude Water Cherenkov) collaboration recently published their 2HWC catalog, listing 39 very high energy (VHE; >100~GeV) gamma-ray sources based on 507 days of observation. Among these, there are nineteen sources that are not associated with previously known TeV sources. We have studied fourteen of these sources without known counterparts with VERITAS and Fermi-LAT. VERITAS detected weak gamma-ray emission in the 1~TeV-30~TeV band in the region of DA 495, a pulsar wind nebula coinciding with 2HWC J1953+294, confirming the discovery of the source by HAWC. We did not find any counterpart for the selected fourteen new HAWC sources from our analysis of Fermi-LAT data for energies higher than 10 GeV. During the search, we detected GeV gamma-ray emission coincident with a known TeV pulsar wind nebula, SNR G54.1+0.3 (VER J1930+188), and a 2HWC source, 2HWC J1930+188. The fluxes for isolated, steady sources in the 2HWC catalog are generally in good agreement with those measured by imaging atmospheric Cherenkov telescopes. However, the VERITAS fluxes for SNR G54.1+0.3, DA 495, and TeV J2032+4130 are lower than those measured by HAWC and several new HAWC sources are not detected by VERITAS. This is likely due to a change in spectral shape, source extension, or the influence of diffuse emission in the source region., Comment: Accepted for publication in the ApJ, Corresponding author: Nahee Park (VERITAS Collaboration), John W. Hewitt (Fermi-LAT Collaboration), Ignacio Taboada (HAWC Collaboration), 30 pages, 12 figures
Published: 2018
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6. First HAWC Observations of the Sun Constrain Steady TeV Gamma-Ray Emission

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

Author: Albert, A., Alfaro, R., Alvarez, C., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Belmont-Moreno, E., BenZvi, S. Y., Brisbois, C., Caballero-Mora, K. S., Capistràn, T., Carramiñana, A., Casanova, S., Castillo, M., Cotzomi, J., de León, S. Coutiño, De León, C., De la Fuente, E., Dichiara, S., Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Engel, K., Enríquez-Rivera, O., Espinoza, C., Fleischhack, H., Fraija, N., García-González, J. A., Garfias, F., González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hona, B., Hueyotl-Zahuantitla, F., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Vargas, H. León, Luis-Raya, G., Lundeen, J., López-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pretz, J., Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Arroyo, M. Seglar, Sinnis, G., Smith, A. J., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Zepeda, A., Zhou, H., Álvarez, J. D., Beacom, J. F., Leane, R. K., Linden, T., Ng, K. C. Y., Peter, A. H. G., and Zhou, B.
Subjects: High Energy Physics - Phenomenology, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics
Abstract: We analyze the Sun as a source for the indirect detection of dark matter through a search for gamma rays from the solar disk. Capture of dark matter by elastic interactions with the solar nuclei followed by annihilation to long-lived mediators can produce a detectable gamma-ray flux. We search three years of data from the High Altitude Water Cherenkov Observatory and find no statistically significant detection of TeV gamma-ray emission from the Sun. Using this, we constrain the spin-dependent elastic scattering cross section of dark matter with protons for dark matter masses above 1 TeV, assuming an unstable mediator with a favorable lifetime. The results complement constraints obtained from Fermi-LAT observations of the Sun and together cover WIMP masses between 4 GeV and $10^6$ GeV. The cross section constraints for mediator decays to gamma rays can be as strong as $\sim10^{-45}$ cm$^{-2}$, which is more than four orders of magnitude stronger than current direct-detection experiments for 1 TeV dark matter mass. The cross-section constraints at higher masses are even better, nearly 7 orders of magnitude better than the current direct-detection constraints for 100 TeV dark matter mass. This demonstration of sensitivity encourages detailed development of theoretical models in light of these powerful new constraints., Comment: 11 pages, 4 figures. See also companion paper 1808.05620. Accepted for publication in Physical Review D
Published: 2018
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8. Observation of Anisotropy of TeV Cosmic Rays with Two Years of HAWC

Author: Abeysekara, A. U., Alfaro, R., Alvarez, C., Alvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Bernal, A., Braun, J., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., De León, C., De la Fuente, E., Hernandez, R. Diaz, Dichiara, S., Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Engel, K., Fiorino, D. W., Fraija, N., García-González, J. A., Garfias, F., Muñoz, A. González, González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hona, B., Hueyotl-Zahuantitla, F., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Lara, A., Lauer, R. J., Lee, W. H., Vargas, H. León, Longinotti, A. L., Luis-Raya, G., Luna-García, R., López-Cámara, D., López-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Arroyo, M. Seglar, Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Vianello, G., Villaseñor, L., Weisgarber, T., Werner, F., Westerhoff, S., Wood, J., Yapici, T., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: After two years of operation, the High-Altitude Water Cherenkov (HAWC) Observatory has analyzed the TeV cosmic-ray sky over an energy range between $2.0$ and $72.8$ TeV. The HAWC detector is a ground-based air-shower array located at high altitude in the state of Puebla, Mexico. Using 300 light-tight water tanks, it collects the Cherenkov light from the particles of extensive air showers from primary gamma rays and cosmic rays. This detection method allows for uninterrupted observation of the entire overhead sky (2~sr instantaneous, 8.5~sr integrated) in the energy range from a few TeV to hundreds of TeV. Like other detectors in the northern and southern hemisphere, HAWC observes an energy-dependent anisotropy in the arrival direction distribution of cosmic rays. The observed cosmic-ray anisotropy is dominated by a dipole moment with phase $\alpha\approx40^{\circ}$ and amplitude that slowly rises in relative intensity from $8\times10^{-4}$ at 2 TeV to $14\times10^{-4}$ around 30.3 TeV, above which the dipole decreases in strength. A significant large-scale ($>60^{\circ}$ in angular extent) signal is also observed in the quadrupole and octupole moments, and significant small-scale features are also present, with locations and shapes consistent with previous observations. Compared to previous measurements in this energy range, the HAWC cosmic-ray sky maps improve on the energy resolution and fit precision of the anisotropy. These data can be used in an effort to better constrain local cosmic-ray accelerators and the intervening magnetic fields., Comment: 22 pages, 14 figures, 2 tables, submission to ApJ
Published: 2018
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9. Search for Dark Matter Gamma-ray Emission from the Andromeda Galaxy with the High-Altitude Water Cherenkov Observatory

Author: Albert, A., Alfaro, R., Alvarez, C., Alvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Bernal, A., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, De León, C., Dichiara, S., Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Eckner, C., Engel, K., Enríquez-Rivera, O., Espinoza, C., Fiorino, D. W., Fraija, N., Galván-Gámez, A., García-González, J. A., Garfias, F., Muñoz, A. González, González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hernandez-Almada, A., Hona, B., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kunde, G. J., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Raya, G. Luis, Luna-García, R., Malone, K., Marinelli, S. S., Martinez, O., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Riviére, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Arroyo, M. Seglar, Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wood, J., Yapici, T., Zaharijas, G., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The Andromeda Galaxy (M31) is a nearby ($\sim$780 kpc) galaxy similar to our own Milky Way. Observational evidence suggests that it resides in a large halo of dark matter (DM), making it a good target for DM searches. We present a search for gamma rays from M31 using 1017 days of data from the High Altitude Water Cherenkov (HAWC) Observatory. With its wide field of view and constant monitoring, HAWC is well-suited to search for DM in extended targets like M31. No DM annihilation or decay signal was detected for DM masses from 1 to 100 TeV in the $b\bar{b}$, $t\bar{t}$, $\tau^{+}\tau^{-}$, $\mu^{+}\mu^{-}$, and $W^{+}W^{-}$ channels. Therefore we present limits on those processes. Our limits nicely complement the existing body of DM limits from other targets and instruments. Specifically the DM decay limits from our benchmark model are the most constraining for DM masses from 25 TeV to 100 TeV in the $b\bar{b}, t\bar{t}$ and $\mu^{+}\mu{-}$ channels. In addition to DM-specific limits, we also calculate general gamma-ray flux limits for M31 in 5 energy bins from 1 TeV to 100 TeV., Comment: published in JCAP. Figure 6 (bottom) has been corrected
Published: 2018
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10. Constraining the $\bar{p}/p$ Ratio in TeV Cosmic Rays with Observations of the Moon Shadow by HAWC

Author: Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Belmont-Moreno, E., BenZvi, S. Y., Braun, J., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, De León, C., la Fuentem, E. D, Hernandez, R. Diaz, Dichiara, S., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Engels, K., Enríquez-Rivera, O., Fleischhack, H., Fraija, N., Galván-Gámez, A., García-González, J. A., Muñoz, A. González, González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hona, B., Hueyotl-Zahuantitla, F., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Lara, A., Lee, W. H., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Luna-García, R., López-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nayerhoda, A., Nellena, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Riviére, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Arroyo, M. Seglar, Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wood, J., Yapici, T., Yodha, G. B., Zepeda, A., Zhou, H., and Alvarez, J. D.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
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., Comment: 10 pages, 5 figures. Accepted by Physical Review D
Published: 2018
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11. Estimate of the energy spectrum of the light component of cosmic rays in HAWC using the shower age and the fraction of hit PMT's

Author: Arteaga-Velázquez, J. C., Hampel-Arias, Z., and Álvarez, J. D.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The High Altitude Water Cherenkov (HAWC) observatory is a ground-based air-shower detector designed to study the TeV gamma and cosmic ray windows. The observatory is composed of a densely packed array of $300$ water Cherenkov tanks, $4.5$ m deep and $7.3$ diameter with $4$ photomultipliers (PMT) each, distributed on a $22,000 \, \mbox{m}^2$ surface. The instrument registers the number of hit PMT's as well as the timing information and the total charge seen by the photomultipliers during the shower event. From the analysis of these data, shower observables such as the arrival direction, the core position at ground, the age and the primary energy are estimated, from which the energy spectrum of cosmic rays and its composition can be studied. In this work, we will describe the methodologies of HAWC cosmic ray analyses, including the Bayesian spectral unfolding procedure used to determine the all-particle and the light component energy spectra of cosmic rays. We will see that the distribution of the shower age vs the fraction of hit PMT's contains information about the composition of cosmic rays., Comment: Presented at the 35th International Cosmic Ray Conference (ICRC2017), Bexco, Busan, Korea. See arXiv:1708.02572 for all HAWC contributions
Published: 2018

12. All-sky Measurement of the Anisotropy of Cosmic Rays at 10 TeV and Mapping of the Local Interstellar Magnetic Field

Author: Abeysekara, AU, Alfaro, R, Alvarez, C, Arceo, R, Arteaga-Velázquez, JC, Rojas, D Avila, Belmont-Moreno, E, BenZvi, SY, Brisbois, C, Capistrán, T, Carramiana, A, Casanova, S, Cotti, U, Cotzomi, J, Díaz-Vélez, JC, De León, C, De la Fuente, E, Dichiara, S, DuVernois, MA, Espinoza, C, Fiorino, DW, Fleischhack, H, Fraija, N, Galván-Gámez, A, García-González, JA, González, MM, Goodman, JA, Hampel-Arias, Z, Harding, JP, Hernandez, S, Hona, B, Hueyotl-Zahuantitla, F, Iriarte, A, Jardin-Blicq, A, Joshi, V, Lara, A, Vargas, H León, Luis-Raya, G, Malone, K, Marinelli, SS, Martínez-Castro, J, Martinez, O, Matthews, JA, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nellen, L, Newbold, M, Nisa, MU, Noriega-Papaqui, R, Pérez-Pérez, EG, Pretz, J, Ren, Z, Rho, CD, Rivière, C, Rosa-González, D, Rosenberg, M, Salazar, H, Greus, F Salesa, Sandoval, A, Schneider, M, Schoorlemmer, H, Sinnis, G, Smith, AJ, Surajbali, P, Taboada, I, Tollefson, K, Torres, I, Villaseor, L, Weisgarber, T, Wood, J, Zepeda, A, Zhou, H, Álvarez, JD, Aartsen, MG, Ackermann, M, Adams, J, Aguilar, JA, Ahlers, M, Ahrens, M, Altmann, D, Andeen, K, Anderson, T, Ansseau, I, Anton, G, Argüelles, C, Auffenberg, J, Axani, S, Backes, P, Bagherpour, H, Bai, X, Barbano, A, Barron, JP, Barwick, SW, Baum, V, Bay, R, Beatty, JJ, Tjus, J Becker, Becker, K-H, and BenZvi, S
Subjects: Particle and High Energy Physics, Astronomical Sciences, Physical Sciences, astroparticle physics, cosmic rays, ISM: magnetic fields, astro-ph.HE, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics, Astronomical sciences, Particle and high energy physics, Space sciences
Abstract: We present the first full-sky analysis of the cosmic ray arrival direction distribution with data collected by the High-Altitude Water Cherenkov and IceCube observatories in the northern and southern hemispheres at the same median primary particle energy of 10 TeV. The combined sky map and angular power spectrum largely eliminate biases that result from partial sky coverage and present a key to probe into the propagation properties of TeV cosmic rays through our local interstellar medium and the interaction between the interstellar and heliospheric magnetic fields. From the map, we determine the horizontal dipole components of the anisotropy δ 0h = 9.16 ×10-4 and δ 6h = 7.25 ×10-4 (±0.04 × 10-4). In addition, we infer the direction (229.°2 ± 3.°5 R.A., 11.°4 ± 3.°0 decl.) of the interstellar magnetic field from the boundary between large-scale excess and deficit regions from which we estimate the missing corresponding vertical dipole component of the large-scale anisotropy to be δN ∼ -3.97+1.0-2.0 × 10-4.
Published: 2019

13. All-sky Measurement of the Anisotropy of Cosmic Rays at 10 TeV and Mapping of the Local Interstellar Magnetic Field

Author: Collaboration, H, Collaboration, I, Abeysekara, AU, Alfaro, R, Alvarez, C, Arceo, R, Arteaga-Velázquez, JC, Rojas, DA, Belmont-Moreno, E, Benzvi, SY, Brisbois, C, Capistrán, T, Carramiana, A, Casanova, S, Cotti, U, Cotzomi, J, Diaz-Vélez, JC, De León, C, Fuente, EDL, Dichiara, S, Duvernois, MA, Espinoza, C, Fiorino, DW, Fleischhack, H, Fraija, N, Galván-Gámez, A, Garcia-González, JA, González, MM, Goodman, JA, Hampel-Arias, Z, Harding, JP, Hernandez, S, Hona, B, Hueyotl-Zahuantitla, F, Iriarte, A, Jardin-Blicq, A, Joshi, V, Lara, A, Vargas, HL, Luis-Raya, G, Malone, K, Marinelli, SS, Martinez-Castro, J, Martinez, O, Matthews, JA, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nellen, L, Newbold, M, Nisa, MU, Noriega-Papaqui, R, Pérez-Pérez, EG, Pretz, J, Ren, Z, Rho, CD, Riviere, C, Rosa-González, D, Rosenberg, M, Salazar, H, Greus, FS, Sandoval, A, Schneider, M, Schoorlemmer, H, Sinnis, G, Smith, AJ, Surajbali, P, Taboada, I, Tollefson, K, Torres, I, Villaseor, L, Weisgarber, T, Wood, J, Zepeda, A, Zhou, H, Alvarez, JD, Aartsen, MG, Ackermann, M, Adams, J, Aguilar, JA, Ahlers, M, Ahrens, M, Altmann, D, Andeen, K, Anderson, T, Ansseau, I, Anton, G, Argüelles, C, Auffenberg, J, Axani, S, Backes, P, Bagherpour, H, Bai, X, Barbano, A, Barron, JP, Barwick, SW, Baum, V, Bay, R, Beatty, JJ, and Tjus, JB
Subjects: astroparticle physics, cosmic rays, ISM: magnetic fields, astro-ph.HE, Astronomy & Astrophysics, Astronomical and Space Sciences, Organic Chemistry, Physical Chemistry, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural)
Abstract: We present the first full-sky analysis of the cosmic ray arrival direction distribution with data collected by the High-Altitude Water Cherenkov and IceCube observatories in the northern and southern hemispheres at the same median primary particle energy of 10 TeV. The combined sky map and angular power spectrum largely eliminate biases that result from partial sky coverage and present a key to probe into the propagation properties of TeV cosmic rays through our local interstellar medium and the interaction between the interstellar and heliospheric magnetic fields. From the map, we determine the horizontal dipole components of the anisotropy δ 0h = 9.16 ×10 -4 and δ 6h = 7.25 ×10 -4 (±0.04 × 10 -4 ). In addition, we infer the direction (229.°2 ± 3.°5 R.A., 11.°4 ± 3.°0 decl.) of the interstellar magnetic field from the boundary between large-scale excess and deficit regions from which we estimate the missing corresponding vertical dipole component of the large-scale anisotropy to be δN ∼ -3.97 +1.0-2.0 × 10 -4 .
Published: 2019

14. Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth

Author: Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Barber, A. S., Bautista-Elivar, N., Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Berley, D., Bernal, A., Braun, J., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, De León, C., De la Fuente, E., Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Ellsworth, R. W., Engel, K., Enríquez-Rivera, O., Fiorino, D. W., Fraija, N., García-González, J. A., Garfias, F., Gerhardt, M., Muñoz, A. González, González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernández, S., Hernández-Almada, A., Hinton, J., Hona, B., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kieda, D., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Raya, G. Luis, Luna-García, R., López-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Vianello, G., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Yodh, G., Younk, P. W., Zepeda, A., Zhou, H., Guo, F., Hahn, J., Li, H., and Zhang, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The unexpectedly high flux of cosmic ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the HighAltitude Water Cherenkov Observatory (HAWC), of extended tera-electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera-electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed. We demonstrate that the leptons emitted by these objects are therefore unlikely to be the origin of the excess positrons, which may have a more exotic origin., Comment: 16 pages (including supplementary material), 5 figures
Published: 2017
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15. A Search for Dark Matter in the Galactic Halo with HAWC

Author: Abeysekara, A. U., Albert, A. M., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Bernal, A., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., De León, C., De la Fuente, E., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Engel, K., Enríquez-Rivera, O., Fiorino, D. W., Fleischhack, H., Fraija, N., García-González, J. A., Garfias, F., Muñoz, A. González, González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hernandez-Almada, A., Hueyotl-Zahuantitla, F., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Luna-García, R., López-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Rodd, N. L., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Safdi, B. R., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Vianello, G., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Yodh, G. B., Younk, P. W., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, High Energy Physics - Phenomenology
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., Comment: 24 pages, 11 figures
Published: 2017
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16. All-particle cosmic ray energy spectrum measured by the HAWC experiment from 10 to 500 TeV

Author: HAWC Collaboration, Alfaro, R., Alvarez, C., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Barber, A. S., Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, De León, C., De la Fuente, E., Hernandez, R. Diaz, Dichiara, S., Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Ellsworth, R. W., Enriquez-Rivera, O., Fiorino, D. W., Fleischhack, H., Fraija, N., García-González, J. A., Muñoz, A. González, González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez-Almada, A., Hinton, J., Hueyotl-Zahuantitla, F., Hui, C. M., Huntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Lara, A., Lauer, R. J., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Raya, G. Luis, Luna-García, R., López-Cámara, D., López-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wood, J., Yapici, T., Zepeda, A., Zhou, H., and Álvarez, J. D.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on the measurement of the all-particle cosmic ray energy spectrum with the High Altitude Water Cherenkov (HAWC) Observatory in the energy range 10 to 500 TeV. HAWC is a ground based air-shower array deployed on the slopes of Volcan Sierra Negra in the state of Puebla, Mexico, and is sensitive to gamma rays and cosmic rays at TeV energies. The data used in this work were taken from 234 days between June 2016 to February 2017. The primary cosmic-ray energy is determined with a maximum likelihood approach using the particle density as a function of distance to the shower core. Introducing quality cuts to isolate events with shower cores landing on the array, the reconstructed energy distribution is unfolded iteratively. The measured all-particle spectrum is consistent with a broken power law with an index of $-2.49\pm0.01$ prior to a break at $(45.7\pm0.1$) TeV, followed by an index of $-2.71\pm0.01$. The spectrum also respresents a single measurement that spans the energy range between direct detection and ground based experiments. As a verification of the detector response, the energy scale and angular resolution are validated by observation of the cosmic ray Moon shadow's dependence on energy., Comment: 16 pages, 11 figures, 4 tables, submission to Physical Review D
Published: 2017
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17. Data Acquisition Architecture and Online Processing System for the HAWC gamma-ray observatory

Author: HAWC collaboration, Abeysekara, A. U., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Barber, A. S., Baughman, B. M., Bautista-Elivar, N., Gonzalez, J. Becerra, Belmont-Moreno, E., BenZvi, S. Y., Berley, D., Rosales, M. Bonilla, Braun, J., Caballero-Lopez, R. A., Caballero-Mora, K. S., Carramiñana, A., Castillo, M., Cotti, U., Cotzomi, J., de la Fuente, E., De León, C., DeYoung, T., Diaz-Cruz, J., Hernandez, R. Diaz, Díaz-Vélez, J. C., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Fiorino, D. W., Fraija, N., Galindo, A., Garfias, F., González, M. M., Goodman, J. A., Grabski, V., Gussert, M., Hampel-Arias, Z., Harding, J. P., Hui, C. M., Hüntemeyer, P., Imran, A., Iriarte, A., Karn, P., Kieda, D., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linares, E. C., Linnemann, J. T., Proper, M. Longo, Luna-García, R., Malone, K., Marinelli, A., Marinelli, S. S., Martinez, O., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A. J., McEnery, J., Torres, E. Mendoza, Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Noriega-Papaqui, R., Oceguera-Becerra, T., Patricelli, B., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Rivière, C., Rosa-González, D., Ruiz-Velasco, E., Ryan, J., Salazar, H., Greus, F. Salesa, Sanchez, F. E., Sandoval, A., Schneider, M., Silich, S., Sinni, G., Smith, A. J., Woodle, K. Sparks, Springer, R. W., Taboada, I., Toale, P. A., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Yodh, G. B., Younk, P. W., Zaborov, D., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: The High Altitude Water Cherenkov observatory (HAWC) is an air shower array devised for TeV gamma-ray astronomy. HAWC is located at an altitude of 4100 m a.s.l. in Sierra Negra, Mexico. HAWC consists of 300 Water Cherenkov Detectors, each instrumented with 4 photomultiplier tubes (PMTs). HAWC re-uses the Front-End Boards from the Milagro experiment to receive the PMT signals. These boards are used in combination with Time to Digital Converters (TDCs) to record the time and the amount of light in each PMT hit (light flash). A set of VME TDC modules (128 channels each) is operated in a continuous (dead time free) mode. The TDCs are read out via the VME bus by Single-Board Computers (SBCs), which in turn are connected to a gigabit Ethernet network. The complete system produces ~ 500 MB/s of raw data. A high-throughput data processing system has been designed and built to enable real-time data analysis. The system relies on off-the-shelf hardware components, an open-source software technology for data transfers (ZeroMQ) and a custom software framework for data analysis (AERIE). Multiple trigger and reconstruction algorithms can be combined and run on blocks of data in a parallel fashion, producing a set of output data streams which can be analyzed in real time with minimal latency (< 5 s). This paper provides an overview of the hardware set-up and an in-depth description of the software design, covering both the TDC data acquisition system and the real-time data processing system. The performance of these systems is also discussed., Comment: 14 pages, 3 figures, submitted to Nucl. Instrum. Meth. A
Published: 2017
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18. HAWC Contributions to the 35th International Cosmic Ray Conference (ICRC2017)

Author: Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Barber, A. S., Gonzalez, J. Becerra, Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Berley, D., Bernal, A., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, De la Fuente, E., De León, C., DeYoung, T., Hernandez, R. Diaz, Diaz-Cruz, L., Díaz-Vélez, J. C., Dichiara, S., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Engel, K., Enriquez-Rivera, O., Fick, B., Fiorino, D. W., Fleischhack, H., Flores, J. L., Fraija, N., García-González, J. A., Garcia-Luna, J. L., Garcia-Torales, G., Garfias, F., Gerhardt, M., González, M. M., Muñoz, A. González, Goodman, J. A., Gussert, M., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hernandez-Almada, A., Hinton, J., Hona, B., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kieda, D., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Proper, M. Longo, López-Coto, R., Raya, G. Luis, Luna-García, R., Malone, K., Marandon, V., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A. J., McEnery, J., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Ryan, J., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Sinnis, G., Smith, A. J., Smith, A. W., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Vianello, G., Weisgarber, T., Westerhoff, S., Wood, J., Yapici, T., Yodh, G. B., Younk, P. W., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract: List of proceedings from the HAWC Collaboration presented at the 35th International Cosmic Ray Conference, 12 July - 20 July 2017, Bexco, Busan, Korea., Comment: List of proceedings from the HAWC Collaboration presented at ICRC2017. Corrected typos in the index of the previous version. Follow the "HTML" link to access the list
Published: 2017

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

Author: The HAWC collaboration, Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Barber, A. S., Bautista-Elivar, N., Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Bernal, A., Braun, J., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, de la Fuente, E., De León, C., DeYoung, T., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Ellsworth, R. W., Engel, K., Fiorino, D. W., Fraija, N., García-González, J. A., Garfias, F., Gerhardt, M., Muñoz, A. González, González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez-Almada, A., Hernandez, S., Hona, B., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kieda, D., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Raya, G. Luis, Luna-García, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Noriega-Papaqui, R., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Vianello, G., Weisgarber, T., Westerhoff, S., Wood, J., Yapici, T., Younk, P. W., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
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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20. The HAWC real-time flare monitor for rapid detection of transient events

Author: Abeysekara, A. U., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Barber, A. S., Bautista-Elivar, N., Gonzalez, J. Becerra, Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Bernal, A., Braun, J., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, De la Fuente, E., De León, C., Díaz-Vélez, J. C., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Engel, K., Fiorino, D. W., Fraija, N., García-González, J. A., Garfias, F., Gerhardt, M., González, M. M., Muñoz, A. González, Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hernandez-Almada, A., Hona, B., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kieda, D., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., López-Cámara, D., López-Coto, R., Raya, G. Luis, Luna-García, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Vianello, G., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Younk, P. W., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present the development of a real-time flare monitor for the High Altitude Water Cherenkov (HAWC) observatory. The flare monitor has been fully operational since 2017 January and is designed to detect very high energy (VHE; $E\gtrsim100$ GeV) transient events from blazars on time scales lasting from 2 minutes to 10 hours in order to facilitate multiwavelength and multimessenger studies. These flares provide information for investigations into the mechanisms that power the blazars' relativistic jets and accelerate particles within them, and they may also serve as probes of the populations of particles and fields in intergalactic space. To date, the detection of blazar flares in the VHE range has relied primarily on pointed observations by imaging atmospheric Cherenkov telescopes. The recently completed HAWC observatory offers the opportunity to study VHE flares in survey mode, scanning 2/3 of the entire sky every day with a field of view of $\sim$1.8 steradians. In this work, we report on the sensitivity of the HAWC real-time flare monitor and demonstrate its capabilities via the detection of three high-confidence VHE events in the blazars Markarian 421 and Markarian 501., Comment: 19 pages, 14 figures, revised version submitted to The Astrophysical Journal on 1 June 2017
Published: 2017
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21. Daily monitoring of TeV gamma-ray emission from Mrk 421, Mrk 501, and the Crab Nebula with HAWC

Author: Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. Avila, Solares, H. A. Ayala, Barber, A. S., Bautista-Elivar, N., Gonzalez, J. Becerra, Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Bernal, A., Braun, J., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, De León, C., De la Fuente, E., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Ellsworth, R. W., Engel, K., Fiorino, D. W., Fraija, N., García-González, J. A., Garfias, F., Gerhardt, M., Muñoz, A. González, González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hernandez-Almada, A., Hona, B., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kieda, D., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Raya, G. Luis, Luna-García, R., López-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pretz, J., Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Vianello, G., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Younk, P. W., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present results from daily monitoring of gamma rays in the energy range $\sim0.5$ to $\sim100$ TeV with the first 17 months of data from the High Altitude Water Cherenkov (HAWC) Observatory. Its wide field of view of 2 steradians and duty cycle of $>95$% are unique features compared to other TeV observatories that allow us to observe every source that transits over HAWC for up to $\sim6$ hours each sidereal day. This regular sampling yields unprecedented light curves from unbiased measurements that are independent of seasons or weather conditions. For the Crab Nebula as a reference source we find no variability in the TeV band. Our main focus is the study of the TeV blazars Markarian (Mrk) 421 and Mrk 501. A spectral fit for Mrk 421 yields a power law index $\Gamma=2.21 \pm0.14_{\mathrm{stat}}\pm0.20_{\mathrm{sys}}$ and an exponential cut-off $E_0=5.4 \pm 1.1_{\mathrm{stat}}\pm 1.0_{\mathrm{sys}}$ TeV. For Mrk 501, we find an index $\Gamma=1.60\pm 0.30_{\mathrm{stat}} \pm 0.20_{\mathrm{sys}}$ and exponential cut-off $E_0=5.7\pm 1.6_{\mathrm{stat}} \pm 1.0_{\mathrm{sys}}$ TeV. The light curves for both sources show clear variability and a Bayesian analysis is applied to identify changes between flux states. The highest per-transit fluxes observed from Mrk 421 exceed the Crab Nebula flux by a factor of approximately five. For Mrk 501, several transits show fluxes in excess of three times the Crab Nebula flux. In a comparison to lower energy gamma-ray and X-ray monitoring data with comparable sampling we cannot identify clear counterparts for the most significant flaring features observed by HAWC., Comment: 18 pages, 10 figures, accepted for publication in The Astrophysical Journal
Published: 2017
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22. Search for Very High Energy Gamma Rays from the Northern $\textit{Fermi}$ Bubble Region with HAWC

Author: Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Barber, A. S., Bautista-Elivar, N., Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Berley, D., Braun, J., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, De León, C., De la Fuente, E., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Ellsworth, R. W., Engel, K., Fick, B., Fiorino, D. W., Fleischhack, H., Fraija, N., García-González, J. A., Garfias, F., Gerhardt, M., Muñoz, A. González, González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hernandez-Almada, A., Hinton, J., Hona, B., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kieda, D., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Raya, G. Luis, Luna-García, R., López-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Vianello, G., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Yodh, G. B., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present a search of very high energy gamma-ray emission from the Northern $\textit{Fermi}$ Bubble region using data collected with the High Altitude Water Cherenkov (HAWC) gamma-ray observatory. The size of the data set is 290 days. No significant excess is observed in the Northern $\textit{Fermi}$ Bubble region, hence upper limits above $1\,\text{TeV}$ are calculated. The upper limits are between $3\times 10^{-7}\,\text{GeV}\, \text{cm}^{-2}\, \text{s}^{-1}\,\text{sr}^{-1}$ and $4\times 10^{-8}\,\text{GeV}\,\text{cm}^{-2}\,\text{s}^{-1}\,\text{sr}^{-1}$. The upper limits disfavor a proton injection spectrum that extends beyond $100\,\text{TeV}$ without being suppressed. They also disfavor a hadronic injection spectrum derived from neutrino measurements.
Published: 2017
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23. Multiwavelength follow-up of a rare IceCube neutrino multiplet

Author: Aartsen, M. G., Ackermann, M., Adams, J., Aguilar, J. A., Ahlers, M., Ahrens, M., Samarai, I. Al, Altmann, D., Andeen, K., Anderson, T., Ansseau, I., Anton, G., Archinger, M., Argüelles, C., Auffenberg, J., Axani, S., Bai, X., Barwick, S. W., Baum, V., Bay, R., Beatty, J. J., Tjus, J. Becker, Becker, K. -H., BenZvi, S., Berley, D., Bernardini, E., Bernhard, A., Besson, D. Z., Binder, G., Bindig, D., Blaufuss, E., Blot, S., Bohm, C., Börner, M., Bos, F., Bose, D., Böser, S., Botner, O., Braun, J., Brayeur, L., Bretz, H. -P., Bron, S., Burgman, A., Carver, T., Casier, M., Cheung, E., Chirkin, D., Christov, A., Clark, K., Classen, L., Coenders, S., Collin, G. H., Conrad, J. M., Cowen, D. F., Cross, R., Day, M., de, J. P. A. M., ré, De Clercq, C., Rosendo, E. del Pino, Dembinski, H., De Ridder, S., Desiati, P., de Vries, K. D., de Wasseige, G., de With, M., DeYoung, T., di Lorenzo, V., Dujmovic, H., Dumm, J. P., Dunkman, M., Eberhardt, B., Ehrhardt, T., Eichmann, B., Eller, P., Euler, S., Evenson, P. A., Fahey, S., Fazely, A. R., Feintzeig, J., Felde, J., Filimonov, K., Finley, C., Flis, S., Fösig, C. -C., Franckowiak, A., Friedman, E., Fuchs, T., Gaisser, T. K., Gallagher, J., Gerhardt, L., Ghorbani, K., Giang, W., Gladstone, L., Glauch, T., Glüsenkamp, T., Goldschmidt, A., Gonzalez, J. G., Grant, D., Griffith, Z., Haack, C., Hallgren, A., Halzen, F., Hansen, E., Hansmann, T., Hanson, K., Hebecker, D., Heereman, D., Helbing, K., Hellauer, R., Hickford, S., Hignight, J., Hill, G. C., Hoffman, K. D., Hoffmann, R., Hoshina, K., Huang, F., Huber, M., Hultqvist, K., In, S., Ishihara, A., Jacobi, E., Japaridze, G. S., Jeong, M., Jero, K., Jones, B. J. P., Kang, W., Kappes, A., Karg, T., Karle, A., Katz, U., Kauer, M., Keivani, A., Kelley, J. L., Kheirandish, A., Kim, J., Kim, M., Kintscher, T., Kiryluk, J., Kittler, T., Klein, S. R., Kohnen, G., Koirala, R., Kolanoski, H., Konietz, R., Köpke, L., Kopper, C., Kopper, S., Koskinen, D. J., Kowalski, M., Krings, K., Kroll, M., Krückl, G., Krüger, C., Kunnen, J., Kunwar, S., Kurahashi, N., Kuwabara, T., Kyriacou, A., Labare, M., Lanfranchi, J. L., Larson, M. J., Lauber, F., Lesiak-Bzdak, M., Leuermann, M., Lu, L., Lünemann, J., Madsen, J., Maggi, G., Mahn, K. B. M., Mancina, S., Mandelartz, M., Maruyama, R., Mase, K., Maunu, R., McNally, F., Meagher, K., Medici, M., Meier, M., Menne, T., Merino, G., Meures, T., Miarecki, S., Micallef, J., Momenté, G., Montaruli, T., Moulai, M., Nahnhauer, R., Naumann, U., Neer, G., Niederhausen, H., Nowicki, S. C., Nygren, D. R., Pollmann, A. Obertacke, Olivas, A., O'Murchadha, A., Palczewski, T., Pandya, H., Pankova, D. V., Peiffer, P., Penek, Ö., Pepper, J. A., Heros, C. Pérez de los, Pieloth, D., Pinat, E., Price, P. B., Przybylski, G. T., Quinnan, M., Raab, C., Rädel, L., Rameez, M., Rawlins, K., Reimann, R., Relethford, B., Relich, M., Resconi, E., Rhode, W., Richman, M., Riedel, B., Robertson, S., Rongen, M., Rott, C., Ruhe, T., Ryckbosch, D., Rysewyk, D., Sabbatini, L., Herrera, S. E. Sanchez, Sandrock, A., Sandroos, J., Sarkar, S., Satalecka, K., Schlunder, P., Schmidt, T., Schoenen, S., Schöneberg, S., Schumacher, L., Seckel, D., Seunarine, S., Soldin, D., Song, M., Spiczak, G. M., Spiering, C., Stachurska, J., Stanev, T., Stasik, A., Stettner, J., Steuer, A., Stezelberger, T., Stokstad, R. G., Stößl, A., Ström, R., Strotjohann, N. L., Sullivan, G. W., Sutherland, M., Taavola, H., Taboada, I., Tatar, J., Tenholt, F., Ter-Antonyan, S., Terliuk, A., Tešić, G., Tilav, S., Toale, P. A., Tobin, M. N., Toscano, S., Tosi, D., Tselengidou, M., Tung, C. F., Turcati, A., Unger, E., Usner, M., Vandenbroucke, J., van Eijndhoven, N., Vanheule, S., van Rossem, M., van Santen, J., Vehring, M., Voge, M., Vogel, E., Vraeghe, M., Walck, C., Wallace, A., Wallraff, M., Wandkowsky, N., Waza, A., Weaver, Ch., Weiss, M. J., Wendt, C., Westerhoff, S., Whelan, B. J., Wickmann, S., Wiebe, K., Wiebusch, C. H., Wille, L., Williams, D. R., Wills, L., Wolf, M., Wood, T. R., Woolsey, E., Woschnagg, K., Xu, D. L., Xu, X. W., Xu, Y., Yanez, J. P., Yodh, G., Yoshida, S., Zoll, M., Stanek, K. Z., Shappee, B. J., Kochanek, C. S., Holoien, T. W. -S., Prieto, J. L., Fox, D. B., DeLaunay, J. J., Turley, C. F., Barthelmy, S. D., Lien, A. Y., Mészáros, P., Murase, K., Kocevski, D., Buehler, R., Giomi, M., Racusin, J. L., Albert, A., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Barber, A. S., Becerril, N. Baustista-Elivar A., Belmont-Moreno, E., Bernal, A., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., de León, S. Coutiño, de la Fuente, E., De León, C., Hernandez, R. Diaz, Díaz-Vélez, J. C., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Engel, K., Fiorino, D. W., Fraija, N., García-González, J. A., Gerhardt, M., Muñoz, A. González, González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Raya, G. Luis, Luna-García, R., López-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Weisgarber, T., Wisher, I. G., Wood, J., Yapici, T., Zepeda, A., Zhou, H., Arcavi, I., Hosseinzadeh, G., Howell, D. A., Valenti, S., McCully, C., Lipunov, V. M., Gorbovskoy, E. S., Tiurina, N. V., Balanutsa, P. V., Kuznetsov, A. S., Kornilov, V. G., Chazov, V., Budnev, N. M., Gress, O. A., Ivanov, K. I., Tlatov, A. G., Lopez, R. Rebolo, Serra-Ricart, M., Evans, P. A., Kennea, J. A., Gehrels, N., Osborne, J. P., Page, K. L., Abeysekara, A. U., Archer, A., Benbow, W., Bird, R., Brantseg, T., Bugaev, V., Cardenzana, J. V, Connolly, M. P., Cui, W., Falcone, A., Feng, Q., Finley, J. P., Fleischhack, H., Fortson, L., Furniss, A., Griffin, S., Grube, J., Hütten, M., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Krause, M., Kumar, S., Lang, M. J., Lin, T. T. Y., McArthur, S., Moriarty, P., Mukherjee, R., Nieto, D., Ong, R. A., Otte, A. N., Pohl, M., Popkow, A., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Staszak, D., Trépanier, S., Tyler, J., Wakely, S. P., Weinstein, A., Wilcox, P., Wilhelm, A., Williams, D. A., Zitzer, B., Bellm, E., Cano, Z., Gal-Yam, A., Kann, D. A., Ofek, E. O., Rigault, M., and Soumagnac, M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: On February 17 2016, the IceCube real-time neutrino search identified, for the first time, three muon neutrino candidates arriving within 100 s of one another, consistent with coming from the same point in the sky. Such a triplet is expected once every 13.7 years as a random coincidence of background events. However, considering the lifetime of the follow-up program the probability of detecting at least one triplet from atmospheric background is 32%. Follow-up observatories were notified in order to search for an electromagnetic counterpart. Observations were obtained by Swift's X-ray telescope, by ASAS-SN, LCO and MASTER at optical wavelengths, and by VERITAS in the very-high-energy gamma-ray regime. Moreover, the Swift BAT serendipitously observed the location 100 s after the first neutrino was detected, and data from the Fermi LAT and HAWC observatory were analyzed. We present details of the neutrino triplet and the follow-up observations. No likely electromagnetic counterpart was detected, and we discuss the implications of these constraints on candidate neutrino sources such as gamma-ray bursts, core-collapse supernovae and active galactic nucleus flares. This study illustrates the potential of and challenges for future follow-up campaigns., Comment: 23 pages, 13 figures, accepted by A&A on July 30 2017
Published: 2017
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24. The 2HWC HAWC Observatory Gamma Ray Catalog

Author: Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Barber, A. S., Bautista-Elivar, N., Gonzalez, J. Becerra, Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Berley, D., Bernal, A., Braun, J., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, de la Fuente, E., De León, C., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Ellsworth, R. W., Engel, K., Fiorino, D. W., Fraija, N., García-González, J. A., Garfias, F., Gerhardt, M., Muñoz, A. González, González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hernandez-Almada, A., Hinton, J., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kieda, D., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Raya, G. Luis, Luna-García, R., López-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Vianello, G., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Younk, P. W., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present the first catalog of TeV gamma-ray sources realized with the recently completed High Altitude Water Cherenkov Observatory (HAWC). It is the most sensitive wide field-of-view TeV telescope currently in operation, with a 1-year survey sensitivity of ~5-10% of the flux of the Crab Nebula. With an instantaneous field of view >1.5 sr and >90% duty cycle, it continuously surveys and monitors the sky for gamma ray energies between hundreds GeV and tens of TeV. HAWC is located in Mexico at a latitude of 19 degree North and was completed in March 2015. Here, we present the 2HWC catalog, which is the result of the first source search realized with the complete HAWC detector. Realized with 507 days of data and represents the most sensitive TeV survey to date for such a large fraction of the sky. A total of 39 sources were detected, with an expected contamination of 0.5 due to background fluctuation. Out of these sources, 16 are more than one degree away from any previously reported TeV source. The source list, including the position measurement, spectrum measurement, and uncertainties, is reported. Seven of the detected sources may be associated with pulsar wind nebulae, two with supernova remnants, two with blazars, and the remaining 23 have no firm identification yet., Comment: Submitted 2017/02/09 to the Astrophysical Journal
Published: 2017
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25. Observation of the Crab Nebula with the HAWC Gamma-Ray Observatory

Author: Abeysekara, A. U., Albert, A., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Barber, A. S., Bautista-Elivar, N., Becerril, A., Belmont-Moreno, E., BenZvi, S. Y., Berley, D., Braun, J., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, de la Fuente, E., De León, C., DeYoung, T., Dingus, B. L., DuVernois, M. A., Díaz-Vélez, J. C., Ellsworth, R. W., Fiorino, D. W., Fraija, N., García-González, J. A., Gerhardt, M., Munoz, A. González, González, M. M., Goodman, J. A., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hernandez-Almada, A., Hinton, J., Hui, C. M., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kaufmann, S., Kieda, D., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Raya, G. Luis, Luna-García, R., López-Coto, R., Malone, K., Marinelli, S. S., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J. A., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Pelayo, R., Pretz, J., Pérez-Pérez, E. G., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Rosenberg, M., Ruiz-Velasco, E., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Sinnis, G., Smith, A. J., Springer, R. W., Surajbali, P., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Yodh, G. B., Younk, P. W., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The Crab Nebula is the brightest TeV gamma-ray source in the sky and has been used for the past 25 years as a reference source in TeV astronomy, for calibration and verification of new TeV instruments. The High Altitude Water Cherenkov Observatory (HAWC), completed in early 2015, has been used to observe the Crab Nebula at high significance across nearly the full spectrum of energies to which HAWC is sensitive. HAWC is unique for its wide field-of-view, nearly 2 sr at any instant, and its high-energy reach, up to 100 TeV. HAWC's sensitivity improves with the gamma-ray energy. Above $\sim$1 TeV the sensitivity is driven by the best background rejection and angular resolution ever achieved for a wide-field ground array. We present a time-integrated analysis of the Crab using 507 live days of HAWC data from 2014 November to 2016 June. The spectrum of the Crab is fit to a function of the form $\phi(E) = \phi_0 (E/E_{0})^{-\alpha -\beta\cdot{\rm{ln}}(E/E_{0})}$. The data is well-fit with values of $\alpha=2.63\pm0.03$, $\beta=0.15\pm0.03$, and log$_{10}(\phi_0~{\rm{cm}^2}~{\rm{s}}~{\rm{TeV}})=-12.60\pm0.02$ when $E_{0}$ is fixed at 7 TeV and the fit applies between 1 and 37 TeV. Study of the systematic errors in this HAWC measurement is discussed and estimated to be $\pm$50\% in the photon flux between 1 and 37 TeV. Confirmation of the Crab flux serves to establish the HAWC instrument's sensitivity for surveys of the sky. The HAWC survey will exceed sensitivity of current-generation observatories and open a new view of 2/3 of the sky above 10 TeV., Comment: Submitted 2017/01/06 to the Astrophysical Journal
Published: 2017
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26. Observation of the Crab Nebula with the HAWC Gamma-Ray Observatory

Author: Abeysekara, AU, Albert, A, Alfaro, R, Alvarez, C, Álvarez, JD, Arceo, R, Arteaga-Velázquez, JC, Solares, HA Ayala, Barber, AS, Bautista-Elivar, N, Becerril, A, Belmont-Moreno, E, BenZvi, SY, Berley, D, Braun, J, Brisbois, C, Caballero-Mora, KS, Capistrán, T, Carramiñana, A, Casanova, S, Castillo, M, Cotti, U, Cotzomi, J, de León, S Coutiño, de la Fuente, E, De León, C, DeYoung, T, Dingus, BL, DuVernois, MA, Díaz-Vélez, JC, Ellsworth, RW, Fiorino, DW, Fraija, N, García-González, JA, Gerhardt, M, Munöz, A González, González, MM, Goodman, JA, Hampel-Arias, Z, Harding, JP, Hernandez, S, Hernandez-Almada, A, Hinton, J, Hui, CM, Hüntemeyer, P, Iriarte, A, Jardin-Blicq, A, Joshi, V, Kaufmann, S, Kieda, D, Lara, A, Lauer, RJ, Lee, WH, Lennarz, D, Vargas, H León, Linnemann, JT, Longinotti, AL, Raya, G Luis, Luna-García, R, López-Coto, R, Malone, K, Marinelli, SS, Martinez, O, Martinez-Castellanos, I, Martínez-Castro, J, Martínez-Huerta, H, Matthews, JA, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nellen, L, Newbold, M, Nisa, MU, Noriega-Papaqui, R, Pelayo, R, Pretz, J, Pérez-Pérez, EG, Ren, Z, Rho, CD, Rivière, C, Rosa-González, D, Rosenberg, M, Ruiz-Velasco, E, Salazar, H, Greus, F Salesa, Sandoval, A, Schneider, M, Schoorlemmer, H, Sinnis, G, Smith, AJ, Springer, RW, Surajbali, P, Taboada, I, Tibolla, O, Tollefson, K, Torres, I, Ukwatta, TN, Villaseñor, L, Weisgarber, T, and Westerhoff, S
Subjects: acceleration of particles, gamma rays: general, ISM: individual objects, astro-ph.HE, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics
Abstract: The Crab Nebula is the brightest TeV gamma-ray source in the sky and has been used for the past 25 years as a reference source in TeV astronomy, for calibration and verification of new TeV instruments. The High Altitude Water Cherenkov Observatory (HAWC), completed in early 2015, has been used to observe the Crab Nebula at high significance across nearly the full spectrum of energies to which HAWC is sensitive. HAWC is unique for its wide field of view, nearly 2 sr at any instant, and its high-energy reach, up to 100 TeV. HAWC's sensitivity improves with the gamma-ray energy. Above ∼1 TeV the sensitivity is driven by the best background rejection and angular resolution ever achieved for a wide-field ground array. We present a time-integrated analysis of the Crab using 507 live days of HAWC data from 2014 November to 2016 June. The spectrum of the Crab is fit to a function of the form φ(E)= φ0(E/E0)-α-β In(E/E0). The data is well fitted with values of α = 2.63 ±0.03, β = 0.15 ±0.03, and log10(φ0cm2s TeV)=-12.60±0.02 when E 0 is fixed at 7 TeV and the fit applies between 1 and 37 TeV. Study of the systematic errors in this HAWC measurement is discussed and estimated to be ±50% in the photon flux between 1 and 37 TeV. Confirmation of the Crab flux serves to establish the HAWC instrument's sensitivity for surveys of the sky. The HAWC all-sky survey will be the deepest survey of the northern sky ever conducted in the multi-TeV band.
Published: 2017

27. Search for Very High-energy Gamma Rays from the Northern Fermi Bubble Region with HAWC

Author: Abeysekara, AU, Albert, A, Alfaro, R, Alvarez, C, Álvarez, JD, Arceo, R, Arteaga-Velázquez, JC, Solares, HA Ayala, Barber, AS, Bautista-Elivar, N, Becerril, A, Belmont-Moreno, E, BenZvi, SY, Berley, D, Braun, J, Brisbois, C, Caballero-Mora, KS, Capistrán, T, Carramiñana, A, Casanova, S, Castillo, M, Cotti, U, Cotzomi, J, de León, S Coutiño, De León, C, De la Fuente, E, Hernandez, R Diaz, Dingus, BL, DuVernois, MA, Díaz-Vélez, JC, Ellsworth, RW, Engel, K, Fick, B, Fiorino, DW, Fleischhack, H, Fraija, N, García-González, JA, Garfias, F, Gerhardt, M, Muñoz, A González, González, MM, Goodman, JA, Hampel-Arias, Z, Harding, JP, Hernandez, S, Hernandez-Almada, A, Hinton, J, Hona, B, Hui, CM, Hüntemeyer, P, Iriarte, A, Jardin-Blicq, A, Joshi, V, Kaufmann, S, Kieda, D, Lara, A, Lauer, RJ, Lee, WH, Lennarz, D, Vargas, H León, Linnemann, JT, Longinotti, AL, Raya, G Luis, Luna-García, R, López-Coto, R, Malone, K, Marinelli, SS, Martinez, O, Martinez-Castellanos, I, Martínez-Castro, J, Martínez-Huerta, H, Matthews, JA, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nellen, L, Newbold, M, Nisa, MU, Noriega-Papaqui, R, Pelayo, R, Pretz, J, Pérez-Pérez, EG, Ren, Z, Rho, CD, Rivière, C, Rosa-González, D, Rosenberg, M, Ruiz-Velasco, E, Salazar, H, Greus, F Salesa, Sandoval, A, Schneider, M, Schoorlemmer, H, Sinnis, G, Smith, AJ, Springer, RW, Surajbali, P, Taboada, I, Tibolla, O, and Tollefson, K
Subjects: astroparticle physics, Galaxy: general, Galaxy: structure, gamma rays: diffuse background, astro-ph.HE, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics
Abstract: We present a search for very high-energy gamma-ray emission from the Northern Fermi Bubble region using data collected with the High Altitude Water Cherenkov gamma-ray observatory. The size of the data set is 290 days. No significant excess is observed in the Northern Fermi Bubble region, so upper limits above 1 TeV are calculated. The upper limits are between and . The upper limits disfavor a proton injection spectrum that extends beyond 100 TeV without being suppressed. They also disfavor a hadronic injection spectrum derived from neutrino measurements.
Published: 2017

28. Search for TeV Gamma-Ray Emission from Point-like Sources in the Inner Galactic Plane with a Partial Configuration of the HAWC Observatory

Author: Abeysekara, A. U., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Barber, A. S., Baughman, B. M., Bautista-Elivar, N., Reyes, A. D. Becerril, Belmont, E., BenZvi, S. Y., Bernal, A., Braun, J., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, de la Fuente, E., De León, C., DeYoung, T., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Enriquez-Rivera, O., Fiorino, D. W., Fraija, N., Garfias, F., González, M. M., Goodman, J. A., Gussert, M., Hampel-Arias, Z., Harding, J. P., Hernandez, S., Hüntemeyer, P., Hui, C. M., Imran, A., Iriarte, A., Karn, P., Kieda, D., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longo, M., Raya, G. Luis, Malone, K., Marinelli, A., Marinelli, S. S., Martinez, H., Martinez, O., Martínez-Castro, J., Matthews, J. A. J., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Noriega-Papaqui, R., Patricelli, B., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Ren, Z., Rivière, C., Rosa-González, D., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Sinnis, G., Smith, A. J., Woodle, K. Sparks, Springer, R. W., Taboada, I., Tibolla, O., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Vrabel, K., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Yodh, G. B., Younk, P. W., Zaborov, D., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: A survey of the inner Galaxy region of Galactic longitude l in [+15, +50] degree and latitude b in [-4,+4] degree is performed using one-third of the High Altitude Water Cherenkov (HAWC) Observatory operated during its construction phase. To address the ambiguities arising from unresolved sources in the data, we use a maximum likelihood technique to identify point source candidates. Ten sources and candidate sources are identified in this analysis. Eight of these are associated with known TeV sources but not all have differential fluxes compatible with previous measurements. Three sources are detected with significances $>5\,\sigma$ after accounting for statistical trials, and are associated with known TeV sources., Comment: Submitted to ApJ, 34 pages, 6 figures. Contact authors: Hao Zhou and C. Michelle Hui
Published: 2015
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29. HAWC Contributions to the 34th International Cosmic Ray Conference (ICRC2015)

Author: HAWC Collaboration, Abeysekara, A. U., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Barber, A. S., Baughman, B. M., Bautista-Elivar, N., Gonzalez, J. Becerra, Becerril, A., Belmont, E., BenZvi, S. Y., Berley, D., Bernal, A., Braun, J., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Castillo, M., Cotti, U., Cotzomi, J., de León, S. Coutiño, de la Fuente, E., De León, C., DeYoung, T., Hernandez, R. Diaz, Diaz-Cruz, L., Díaz-Vélez, J. C., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Engel, K., Enriquez-Rivera, O., Fick, B., Fiorino, D. W., Flores, J. L., Fraija, N., Garcia-Torales, G., Garfias, F., González, M. M., Goodman, J. A., Gussert, M., Hampel-Arias, Z., Hansen, P., Harding, J. Patrick, Hernandez, S., Hui, C. M., Hüntemeyer, P., Imran, A., Iriarte, A., Karn, P., Kieda, D., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Proper, M. Longo, Raya, G. Luis, Luna-García, R., Malone, K., Marinelli, A., Marinelli, S. S., Martinez, H., Martinez, O., Martínez-Castro, J., Matthews, J. A. J., McEnery, J., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Nisa, M. Un, Noriega-Papaqui, R., Oceguera-Becerra, T., Patricelli, B., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Ren, Z., Rho, C. D., Rivière, C., Rosa-González, D., Ryan, J., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Sinnis, G., Smith, A. J., Smith, A. W., Woodle, K. Sparks, Springer, R. W., Taboada, I., Tibolla, O., Toale, P. A., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yapici, T., Yodh, G. B., Younk, P. W., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract: List of proceedings from the HAWC Collaboration presented at the 34th International Cosmic Ray Conference, 30 July - 6 August 2015, The Hague, The Netherlands., Comment: List of proceedings from the HAWC Collaboration presented at ICRC2015. Follow the "HTML" link to access the list
Published: 2015

30. SEARCH FOR TeV GAMMA-RAY EMISSION FROM POINT-LIKE SOURCES IN THE INNER GALACTIC PLANE WITH A PARTIAL CONFIGURATION OF THE HAWC OBSERVATORY

Author: Abeysekara, AU, Alfaro, R, Alvarez, C, Álvarez, JD, Arceo, R, Arteaga-Velázquez, JC, Solares, HA Ayala, Barber, AS, Baughman, BM, Bautista-Elivar, N, Reyes, AD Becerril, Belmont, E, BenZvi, SY, Bernal, A, Braun, J, Caballero-Mora, KS, Capistrán, T, Carramiñana, A, Casanova, S, Castillo, M, Cotti, U, Cotzomi, J, de León, S Coutińo, de la Fuente, E, De León, C, DeYoung, T, Hernandez, R Diaz, Dingus, BL, DuVernois, MA, Ellsworth, RW, Enriquez-Rivera, O, Fiorino, DW, Fraija, N, Garfias, F, González, MM, Goodman, JA, Gussert, M, Hampel-Arias, Z, Harding, JP, Hernandez, S, Hüntemeyer, P, Hui, CM, Imran, A, Iriarte, A, Karn, P, Kieda, D, Lara, A, Lauer, RJ, Lee, WH, Lennarz, D, Vargas, H León, Linnemann, JT, Longo, M, Raya, G Luis, Malone, K, Marinelli, A, Marinelli, SS, Martinez, H, Martinez, O, Martínez-Castro, J, Matthews, JA, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nellen, L, Newbold, M, Noriega-Papaqui, R, Patricelli, B, Pelayo, R, Pérez-Pérez, EG, Pretz, J, Ren, Z, Rivière, C, Rosa-González, D, Salazar, H, Greus, F Salesa, Sandoval, A, Schneider, M, Sinnis, G, Smith, AJ, Woodle, K Sparks, Springer, RW, Taboada, I, Tibolla, O, Tollefson, K, Torres, I, Ukwatta, TN, Villaseñor, L, Vrabel, K, Weisgarber, T, Westerhoff, S, Wisher, IG, Wood, J, Yapici, T, Yodh, GB, Younk, PW, Zaborov, D, Zepeda, A, and Zhou, H
Subjects: astroparticle physics, gamma rays: diffuse background, gamma rays: general, astro-ph.HE, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics
Abstract: A survey of the inner Galaxy region of Galactic longitude l ∈[+15,+50] and latitude b ∈ [-4, +4] is performed using one-third of the High Altitude Water Cherenkov Observatory, operated during ts construction phase. To address the ambiguities arising from unresolved sources in the data, we use a maximum likelihood technique to identify point source candidates. Ten sources and candidate sources are identified in this analysis. Eight of these are associated with known TeV sources but not all have ifferential fluxes that are compatible with previous measurements. Three sources are detected with significances >5 sigma; after accounting for statistical trials, and are associated with known TeV sources.
Published: 2016

31. Search for gamma-rays from the unusually bright GRB 130427A with the HAWC Gamma-ray Observatory

Author: The HAWC collaboration, Abeysekara, A. U., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Barber, A. S., Baughman, B. M., Bautista-Elivar, N., BenZvi, S. Y., Rosales, M. Bonilla, Braun, J., Caballero-Mora, K. S., Carramiñana, A., Castillo, M., Cotti, U., Cotzomi, J., de la Fuente, E., De León, C., DeYoung, T., Hernandez, R. Diaz, Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Fiorino, D. W., Fraija, N., Galindo, A., Garfias, F., González, M. M., Goodman, J. A., Gussert, M., Hampel-Arias, Z., Harding, J. P., Hüntemeyer, P., Hui, C. M., Imran, A., Iriarte, A., Karn, P., Kieda, D., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longo, M., Luna-García, R., Malone, K., Marinelli, A., Marinelli, S. S., Martinez, H., Martinez, O., Martínez-Castro, J., Matthews, J. A., Torres, E. Mendoza, Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Noriega-Papaqui, R., Oceguera-Becerra, T. O., Patricelli, B., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Rivière, C., Rosa-González, D., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Sinnis, G., Smith, A. J., Woodle, K. Sparks, Springer, R. W., Taboada, I., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yodh, G. B., Younk, P. W., Zaborov, D., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The first limits on the prompt emission from the long gamma-ray burst (GRB) 130427A in the $>100\nobreakspace\rm{GeV}$ energy band are reported. GRB 130427A was the most powerful burst ever detected with a redshift $z\lesssim0.5$ and featured the longest lasting emission above $100\nobreakspace\rm{MeV}$. The energy spectrum extends at least up to $95\nobreakspace\rm{GeV}$, clearly in the range observable by the High Altitude Water Cherenkov (HAWC) Gamma-ray Observatory, a new extensive air shower detector currently under construction in central Mexico. The burst occurred under unfavourable observation conditions, low in the sky and when HAWC was running 10% of the final detector. Based on the observed light curve at MeV-GeV energies, eight different time periods have been searched for prompt and delayed emission from this GRB. In all cases, no statistically significant excess of counts has been found and upper limits have been placed. It is shown that a similar GRB close to zenith would be easily detected by the full HAWC detector, which will be completed soon. The detection rate of the full HAWC detector may be as high as one to two GRBs per year. A detection could provide important information regarding the high energy processes at work and the observation of a possible cut-off beyond the $\mathit{Fermi}$-LAT energy range could be the signature of gamma-ray absorption, either in the GRB or along the line of sight due to the extragalactic background light., Comment: 10 pages, 4 figures, published in ApJ
Published: 2014
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32. Observation of Small-scale Anisotropy in the Arrival Direction Distribution of TeV Cosmic Rays with HAWC

Author: Abeysekara, A. U., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Barber, A. S., Baughman, B. M., Bautista-Elivar, N., Belmont, E., BenZvi, S. Y., Berley, D., Rosales, M. Bonilla, Braun, J., Caballero-Mora, K. S., Carramiñana, A., Castillo, M., Cotti, U., Cotzomi, J., de la Fuente, E., De León, C., DeYoung, T., Hernandez, R. Diaz, Díaz-Vélez, J. C., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Fiorino, D. W., Fraija, N., Galindo, A., Garfias, F., González, M. M., Goodman, J. A., Gussert, M., Hampel-Arias, Z., Harding, J. P., Hüntemeyer, P., Hui, C. M., Imran, A., Iriarte, A., Karn, P., Kieda, D., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linnemann, J. T., Longo, M., Luna-García, R., Malone, K., Marinelli, A., Marinelli, S. S., Martinez, H., Martinez, O., Martínez-Castro, J., Matthews, J. A. J., McEnery, J., Torres, E. Mendoza, Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Noriega-Papaqui, R., Oceguera-Becerra, T., Patricelli, B., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Rivière, C., Rosa-González, D., Ruiz-Velasco, E., Ryan, J., Salazar, H., Greus, F. Salesa, Sandoval, A., Schneider, M., Sinnis, G., Smith, A. J., Woodle, K. Sparks, Springer, R. W., Taboada, I., Toale, P. A., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yodh, G. B., Younk, P. W., Zaborov, D., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The High-Altitude Water Cherenkov (HAWC) Observatory is sensitive to gamma rays and charged cosmic rays at TeV energies. The detector is still under construction, but data acquisition with the partially deployed detector started in 2013. An analysis of the cosmic-ray arrival direction distribution based on $4.9\times 10^{10}$ events recorded between June 2013 and February 2014 shows anisotropy at the $10^{-4}$ level on angular scales of about $10^\circ$. The HAWC cosmic-ray sky map exhibits three regions of significantly enhanced cosmic-ray flux; two of these regions were first reported by the Milagro experiment. A third region coincides with an excess recently reported by the ARGO-YBJ experiment. An angular power spectrum analysis of the sky shows that all terms up to $\ell=15$ contribute significantly to the excesses., Comment: 12 pages, 11 figures. Accepted by The Astrophysical Journal
Published: 2014
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33. VAMOS: a Pathfinder for the HAWC Gamma-Ray Observatory

Author: Abeysekara, A. U., Alfaro, R., Alvarez, C., Álvarez, J. D., Ángeles, F., Arceo, R., Arteaga-Velázquez, J. C., Avila-Aroche, A., Solares, H. A. Ayala, Badillo, C., Barber, A. S., Baughman, B. M., Bautista-Elivar, N., Gonzalez, J. Becerra, Belmont, E., Benítez, E., BenZvi, S. Y., Berley, D., Bernal, A., Rosales, M. Bonilla, Braun, J., Caballero-Lopez, R. A., Caballero-Mora, K. S., Cabrera, I., Carramiñana, A., Castañeda-Martínez, L., Castillo, M., Cotti, U., Cotzomi, J., de la Fuente, E., De León, C., DeYoung, T., Diaz-Azuara, A., Diaz-Cruz, L., Hernandez, R. Diaz, Díaz-Vélez, J. C., Dingus, B. L., Dultzin, D., DuVernois, M. A., Ellsworth, R. W., Fernandez, A., Fiorino, D. W., Fraija, N., Galindo, A., García-Torales, G., Garfias, F., González, A., González, L. X., González, M. M., Goodman, J. A., Grabski, V., Gussert, M., Guzmán-Cerón, C., Hampel-Arias, Z., Harding, J. P., Hernández-Cervantes, L., Hui, C. M., Hüntemeyer, P., Imran, A., Iriarte, A., Karn, P., Kieda, D., Kunde, G. J., Langarica, R., Lara, A., Lara, G., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linares, E. C., Linnemann, J. T., Longo, M., Luna-Garcia, R., Marinelli, A., Martínez, L. A., Martínez, H., Martínez, O., Martínez-Castro, J., Martos, M., Matthews, J. A. J., McEnery, J., Torres, E. Mendoza, Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nava, J., Nellen, L., Newbold, M., Noriega-Papaqui, R., Oceguera-Becerra, T., Page, D. P., Patricelli, B., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Ramírez, I., Renter, A., Rivière, C., Rosa-González, D., Ruiz-Sala, F., Ruiz-Velasco, E. L., Ryan, J., Sacahui, J. R., Salazar, H., Salesa, F., Sandoval, A., Santos, E., Schneider, M., Silich, S., Sinnis, G., Smith, A. J., Woodle, K. Sparks, Springer, R. W., Suarez, F., Taboada, I., Tepe, A., Toale, P. A., Tollefson, K., Torres, I., Tinoco, S., Ukwatta, T. N., Galicia, J. F. Valdés, Vanegas, P., Vázquez, A., Villaseñor, L., Wall, W., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yodh, G. B., Younk, P. W., Zaborov, D., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: VAMOS was a prototype detector built in 2011 at an altitude of 4100m a.s.l. in the state of Puebla, Mexico. The aim of VAMOS was to finalize the design, construction techniques and data acquisition system of the HAWC observatory. HAWC is an air-shower array currently under construction at the same site of VAMOS with the purpose to study the TeV sky. The VAMOS setup included six water Cherenkov detectors and two different data acquisition systems. It was in operation between October 2011 and May 2012 with an average live time of 30%. Besides the scientific verification purposes, the eight months of data were used to obtain the results presented in this paper: the detector response to the Forbush decrease of March 2012, and the analysis of possible emission, at energies above 30 GeV, for long gamma-ray bursts GRB111016B and GRB120328B., Comment: Accepted for pubblication in Astroparticle Physics Journal (20 pages, 10 figures). Corresponding authors: A.Marinelli and D.Zaborov
Published: 2014
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34. Milagro Limits and HAWC Sensitivity for the Rate-Density of Evaporating Primordial Black Holes

Author: Abdo, A. A., Abeysekara, A. U., Alfaro, R., Allen, B. T., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Aune, T., Solares, H. A. Ayala, Barber, A. S., Baughman, B. M., Bautista-Elivar, N., Gonzalez, J. Becerra, Belmont, E., BenZvi, S. Y., Berley, D., Rosales, M. Bonilla, Braun, J., Caballero-Lopez, R. A., Caballero-Mora, K. S., Carramiñana, A., Castillo, M., Chen, C., Christopher, G. E., Cotti, U., Cotzomi, J., de la Fuente, E., De León, C., DeYoung, T., Hernandez, R. Diaz, Diaz-Cruz, L., Díaz-Vélez, J. C., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Fiorino, D. W., Fraija, N., Galindo, A., Garfias, F., González, M. M., Goodman, J. A., Grabski, V., Gussert, M., Hampel-Arias, Z., Harding, J. P., Hays, E., Hoffman, C. M., Hui, C. M., Hüntemeyer, P., Imran, A., Iriarte, A., Karn, P., Kieda, D., Kolterman, B. E., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linares, E. C., Linnemann, J. T., Longo, M., Luna-GarcIa, R., MacGibbon, J. H., Marinelli, A., Marinelli, S. S., Martinez, H., Martinez, O., Martínez-Castro, J., Matthews, J. A. J., McEnery, J., Torres, E. Mendoza, Mincer, A. I., Miranda-Romagnoli, P., Moreno, E., Morgan, T., Mostafá, M., Nellen, L., Nemethy, P., Newbold, M., Noriega-Papaqui, R., Oceguera-Becerra, T., Patricelli, B., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Rivière, C., Rosa-González, D., Ryan, J., Salazar, H., Salesa, F., Sandoval, A., Parkinson, P. M. Saz, Schneider, M., Shoup, A., Silich, S., Sinnis, G., Smith, A. J., Stump, D., Woodle, K. Sparks, Springer, R. W., Taboada, I., Toale, P. A., Tollefson, K., Torres, I., Ukwatta, T. N., Vasileiou, V., Villaseñor, L., Walker, G. P., Weisgarber, T., Westerhoff, S., Williams, D. A., Wisher, I. G., Wood, J., Yodh, G. B., Younk, P. W., Zaborov, D., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of ~5.0 x 10^14 g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV - TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events., Comment: Accepted to Astroparticle Physics Journal (25 Pages, 3 figures and 7 tables). Corresponding author: T. N. Ukwatta
Published: 2014
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35. The Sensitivity of HAWC to High-Mass Dark Matter Annihilations

Author: Abeysekara, A. U., Alfaro, R., Alvarez, C., Alvarez, J. D., Arceo, R., Arteaga-Velazquez, J. C., Solares, H. A. Ayala, Barber, A. S., Baughman, B. M., Bautista-Elivar, N., Gonzalez, J. Becerra, Belmont, E., BenZvi, S. Y., Berley, D., Rosales, M. Bonilla, Braun, J., Caballero-Lopez, R. A., Caballero-Mora, K. S., Carraminana, A., Castillo, M., Cotti, U., Cotzomi, J., de la Fuente, E., De Leon, C., DeYoung, T., Hernandez, R. Diaz, Diaz-Cruz, L., Diaz-Velez, J. C., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., E., S. F., Fiorino, D. W., Fraija, N., Galindo, A., Garfias, F., Gonzalez, M. M., Goodman, J. A., Grabski, V., Gussert, M., Hampel-Arias, Z., Harding, J. P., Hui, C. M., Huentemeyer, P., Imran, A., Iriarte, A., Karn, P., Kieda, D., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. Leon, Linares, E. C., Linnemann, J. T., Longo, M., Luna-Garcia, R., Marinelli, A., Martinez, H., Martinez, O., Martinez-Castro, J., Matthews, J. A. J., McEnery, J., Torres, E. Mendoza, Miranda-Romagnoli, P., Moreno, E., Mostafa, M., Nellen, L., Newbold, M., Noriega-Papaqui, R., Oceguera-Becerra, T., Patricelli, B., Pelayo, R., Perez-Perez, E. G., Pretz, J., Riviere, C., Rosa-Gonzalez, D., Ryan, J., Salazar, H., Salesa, F., Sandoval, A., Schneider, M., Silich, S., Sinnis, G., Smith, A. J., Woodle, K. Sparks, Springer, R. W., Taboada, I., Toale, P. A., Tollefson, K., Torres, I., Ukwatta, T. N., Villasenor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yodh, G. B., Younk, P. W., Zaborov, D., Zepeda, A., Zhou, H., and Abazajian, K. N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, High Energy Physics - Phenomenology
Abstract: The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view detector sensitive to gamma rays of 100 GeV to a few hundred TeV. Located in central Mexico at 19 degrees North latitude and 4100 m above sea level, HAWC will observe gamma rays and cosmic rays with an array of water Cherenkov detectors. The full HAWC array is scheduled to be operational in Spring 2015. In this paper, we study the HAWC sensitivity to the gamma-ray signatures of high-mass (multi- TeV) dark matter annihilation. The HAWC observatory will be sensitive to diverse searches for dark matter annihilation, including annihilation from extended dark matter sources, the diffuse gamma-ray emission from dark matter annihilation, and gamma-ray emission from non-luminous dark matter subhalos. Here we consider the HAWC sensitivity to a subset of these sources, including dwarf galaxies, the M31 galaxy, the Virgo cluster, and the Galactic center. We simulate the HAWC response to gamma rays from these sources in several well-motivated dark matter annihilation channels. If no gamma-ray excess is observed, we show the limits HAWC can place on the dark matter cross-section from these sources. In particular, in the case of dark matter annihilation into gauge bosons, HAWC will be able to detect a narrow range of dark matter masses to cross-sections below thermal. HAWC should also be sensitive to non-thermal cross-sections for masses up to nearly 1000 TeV. The constraints placed by HAWC on the dark matter cross-section from known sources should be competitive with current limits in the mass range where HAWC has similar sensitivity. HAWC can additionally explore higher dark matter masses than are currently constrained., Comment: 15 pages, 4 figures, version to be published in PRD
Published: 2014
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36. HAWC Contributions to the 34th International Cosmic Ray Conference (ICRC2015)

Author: Collaboration, HAWC, Abeysekara, AU, Alfaro, R, Alvarez, C, Álvarez, JD, Arceo, R, Arteaga-Velázquez, JC, Solares, HA Ayala, Barber, AS, Baughman, BM, Bautista-Elivar, N, Gonzalez, J Becerra, Becerril, A, Belmont, E, BenZvi, SY, Berley, D, Bernal, A, Braun, J, Caballero-Mora, KS, Capistrán, T, Carramiñana, A, Castillo, M, Cotti, U, Cotzomi, J, León, S Coutiño de, Fuente, E de la, León, C De, DeYoung, T, Hernandez, R Diaz, Diaz-Cruz, L, Díaz-Vélez, JC, Dingus, BL, DuVernois, MA, Ellsworth, RW, Engel, K, Enriquez-Rivera, O, Fick, B, Fiorino, DW, Flores, JL, Fraija, N, Garcia-Torales, G, Garfias, F, González, MM, Goodman, JA, Gussert, M, Hampel-Arias, Z, Hansen, P, Harding, J Patrick, Hernandez, S, Hui, CM, Hüntemeyer, P, Imran, A, Iriarte, A, Karn, P, Kieda, D, Kunde, GJ, Lara, A, Lauer, RJ, Lee, WH, Lennarz, D, Vargas, H León, Linnemann, JT, Proper, M Longo, Raya, G Luis, Luna-García, R, Malone, K, Marinelli, A, Marinelli, SS, Martinez, H, Martinez, O, Martínez-Castro, J, Matthews, JAJ, McEnery, J, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nellen, L, Newbold, M, Nisa, M Un, Noriega-Papaqui, R, Oceguera-Becerra, T, Patricelli, B, Pelayo, R, Pérez-Pérez, EG, Pretz, J, Ren, Z, Rho, CD, Rivière, C, Rosa-González, D, Ryan, J, Salazar, H, Greus, F Salesa, Sandoval, A, Schneider, M, Sinnis, G, Smith, AJ, Smith, AW, Woodle, K Sparks, Springer, RW, and Taboada, I
Subjects: astro-ph.HE, hep-ex
Abstract: List of proceedings from the HAWC Collaboration presented at the 34thInternational Cosmic Ray Conference, 30 July - 6 August 2015, The Hague, TheNetherlands.
Published: 2015

37. Milagro limits and HAWC sensitivity for the rate-density of evaporating Primordial Black Holes

Author: Abdo, AA, Abeysekara, AU, Alfaro, R, Allen, BT, Alvarez, C, Álvarez, JD, Arceo, R, Arteaga-Velázquez, JC, Aune, T, Solares, HA Ayala, Barber, AS, Baughman, BM, Bautista-Elivar, N, Gonzalez, J Becerra, Belmont, E, BenZvi, SY, Berley, D, Rosales, M Bonilla, Braun, J, Caballero-Lopez, RA, Caballero-Mora, KS, Carramiñana, A, Castillo, M, Christopher, GE, Cotti, U, Cotzomi, J, de la Fuente, E, De León, C, DeYoung, T, Hernandez, R Diaz, Diaz-Cruz, L, Díaz-Vélez, JC, Dingus, BL, DuVernois, MA, Ellsworth, RW, Fiorino, DW, Fraija, N, Galindo, A, Garfias, F, González, MM, Goodman, JA, Grabski, V, Gussert, M, Hampel-Arias, Z, Harding, JP, Hays, E, Hoffman, CM, Hui, CM, Hüntemeyer, P, Imran, A, Iriarte, A, Karn, P, Kieda, D, Kolterman, BE, Kunde, GJ, Lara, A, Lauer, RJ, Lee, WH, Lennarz, D, Vargas, H León, Linares, EC, Linnemann, JT, Longo, M, Luna-GarcIa, R, MacGibbon, JH, Marinelli, A, Marinelli, SS, Martinez, H, Martinez, O, Martínez-Castro, J, Matthews, JAJ, McEnery, J, Torres, E Mendoza, Mincer, AI, Miranda-Romagnoli, P, Moreno, E, Morgan, T, Mostafá, M, Nellen, L, Nemethy, P, Newbold, M, Noriega-Papaqui, R, Oceguera-Becerra, T, Patricelli, B, Pelayo, R, Pérez-Pérez, EG, Pretz, J, Rivière, C, Rosa-González, D, Ruiz-Velasco, E, Ryan, J, Salazar, H, Salesa, F, Sandoval, A, Parkinson, PM Saz, Schneider, M, Silich, S, Sinnis, G, Smith, AJ, and Stump, D
Subjects: Primordial Black Holes, HAWC, Milagro, Very High Energy Bursts, astro-ph.HE, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of ∼5.0 × 1014 g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV-TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events.
Published: 2015

38. VAMOS: A pathfinder for the HAWC gamma-ray observatory

Author: Abeysekara, AU, Alfaro, R, Alvarez, C, Álvarez, JD, Ángeles, F, Arceo, R, Arteaga-Velázquez, JC, Avila-Aroche, A, Solares, HA Ayala, Badillo, C, Barber, AS, Baughman, BM, Bautista-Elivar, N, Gonzalez, J Becerra, Belmont, E, Benítez, E, BenZvi, SY, Berley, D, Bernal, A, Rosales, M Bonilla, Braun, J, Caballero-Lopez, RA, Caballero-Mora, KS, Cabrera, I, Carramiñana, A, Castañeda-Martínez, L, Castillo, M, Cotti, U, Cotzomi, J, de la Fuente, E, De León, C, DeYoung, T, Diaz-Azuara, A, Diaz-Cruz, L, Hernandez, R Diaz, Díaz-Vélez, JC, Dingus, BL, Dultzin, D, DuVernois, MA, Ellsworth, RW, Fernandez, A, Fiorino, DW, Fraija, N, Galindo, A, García-Torales, G, Garfias, F, González, A, González, LX, González, MM, Goodman, JA, Grabski, V, Gussert, M, Guzmán-Cerón, C, Hampel-Arias, Z, Harding, JP, Hernández-Cervantes, L, Hui, CM, Hüntemeyer, P, Imran, A, Iriarte, A, Karn, P, Kieda, D, Kunde, GJ, Langarica, R, Lara, A, Lara, G, Lauer, RJ, Lee, WH, Lennarz, D, Vargas, H León, Linares, EC, Linnemann, JT, Longo, M, Luna-Garcia, R, Marinelli, A, Martínez, LA, Martínez, H, Martínez, O, Martínez-Castro, J, Martos, M, Matthews, JAJ, McEnery, J, Torres, E Mendoza, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nava, J, Nellen, L, Newbold, M, Noriega-Papaqui, R, Oceguera-Becerra, T, Page, DP, Patricelli, B, Pelayo, R, Pérez-Pérez, EG, Pretz, J, Ramírez, I, Rentería, A, Rivière, C, and Rosa-González, D
Subjects: Detector prototype, Scientific verification, TeV cosmic rays, astro-ph.IM, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: VAMOS1 was a prototype detector built in 2011 at an altitude of 4100 m a.s.l. in the state of Puebla, Mexico. The aim of VAMOS was to finalize the design, construction techniques and data acquisition system of the HAWC observatory. HAWC is an air-shower array currently under construction at the same site of VAMOS with the purpose to study the TeV sky. The VAMOS setup included six water Cherenkov detectors and two different data acquisition systems. It was in operation between October 2011 and May 2012 with an average live time of 30%. Besides the scientific verification purposes, the eight months of data were used to obtain the results presented in this paper: the detector response to the Forbush decrease of March 2012, and the analysis of possible emission, at energies above 30 GeV, for long gamma-ray bursts GRB111016B and GRB120328B.
Published: 2015

39. SEARCH FOR GAMMA-RAYS FROM THE UNUSUALLY BRIGHT GRB 130427A WITH THE HAWC GAMMA-RAY OBSERVATORY

Author: Abeysekara, AU, Alfaro, R, Alvarez, C, Álvarez, JD, Arceo, R, Arteaga-Velázquez, JC, Solares, HA Ayala, Barber, AS, Baughman, BM, Bautista-Elivar, N, BenZvi, SY, Rosales, M Bonilla, Braun, J, Caballero-Mora, KS, Carramiñana, A, Castillo, M, Cotti, U, Cotzomi, J, de la Fuente, E, De León, C, DeYoung, T, Hernandez, R Diaz, Dingus, BL, DuVernois, MA, Ellsworth, RW, Fiorino, DW, Fraija, N, Galindo, A, Garfias, F, González, MM, Goodman, JA, Gussert, M, Hampel-Arias, Z, Harding, JP, Hüntemeyer, P, Hui, CM, Imran, A, Iriarte, A, Karn, P, Kieda, D, Kunde, GJ, Lara, A, Lauer, RJ, Lee, WH, Lennarz, D, Vargas, H León, Linnemann, JT, Longo, M, Luna-García, R, Malone, K, Marinelli, A, Marinelli, SS, Martinez, H, Martinez, O, Martínez-Castro, J, Matthews, JAJ, Torres, E Mendoza, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nellen, L, Newbold, M, Noriega-Papaqui, R, Oceguera-Becerra, TO, Patricelli, B, Pelayo, R, Pérez-Pérez, EG, Pretz, J, Rivière, C, Rosa-González, D, Salazar, H, Greus, F Salesa, Sandoval, A, Schneider, M, Sinnis, G, Smith, AJ, Woodle, K Sparks, Springer, RW, Taboada, I, Tollefson, K, Torres, I, Ukwatta, TN, Villaseñor, L, Weisgarber, T, Westerhoff, S, Wisher, IG, Wood, J, Yodh, GB, Younk, PW, Zaborov, D, Zepeda, A, and Zhou, and H
Subjects: gamma-ray burst: individual, gamma rays: general, astro-ph.HE, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics
Abstract: The first limits on the prompt emission from the long gamma-ray burst (GRB) 130427A in the >100 GeV energy band are reported. GRB 130427A was the most powerful burst ever detected with a redshift z ≲ 0.5 and featured the longest lasting emission above 100 MeV. The energy spectrum extends at least up to 95 GeV, clearly in the range observable by the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory, a new extensive air shower detector currently under construction in central Mexico. The burst occurred under unfavorable observation conditions, low in the sky and when HAWC was running 10% of the final detector. Based on the observed light curve at MeV-GeV energies, eight different time periods have been searched for prompt and delayed emission from this GRB. In all cases, no statistically significant excess of counts has been found and upper limits have been placed. It is shown that a similar GRB close to zenith would be easily detected by the full HAWC detector, which will be completed soon. The detection rate of the full HAWC detector may be as high as one to two GRBs per year. A detection could provide important information regarding the high energy processes at work and the observation of a possible cut-off beyond the Fermi Large Area Telescope energy range could be the signature of gamma-ray absorption, either in the GRB or along the line of sight due to the extragalactic background light.
Published: 2015

40. The HAWC Gamma-Ray Observatory: Observations of Cosmic Rays

Author: HAWC Collaboration, Abeysekara, A. U., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Barber, A. S., Baughman, B. M., Bautista-Elivar, N., Belmont, E., BenZvi, S. Y., Berley, D., Rosales, M. Bonilla, Braun, J., Caballero-Lopez, R. A., Caballero-Mora, K. S., Carramiñana, A., Castillo, M., Cotti, U., Cotzomi, J., de la Fuente, E., De León, C., DeYoung, T., Hernandez, R. Diaz, Díaz-Vélez, J. C., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Fernandez, A., Fiorino, D. W., Fraija, N., Galindo, A., Garfias, F., González, L. X., González, M. M., Goodman, J. A., Grabski, V., Gussert, M., Hampel-Arias, Z., Hui, C. M., Hüntemeyer, P., Imran, A., Iriarte, A., Karn, P., Kieda, D., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linares, E. C., Linnemann, J. T., Longo, M., Luna-GarcIa, R., Marinelli, A., Martinez, H., Martinez, O., Martínez-Castro, J., Matthews, J. A. J., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nava, J., Nellen, L., Newbold, M., Noriega-Papaqui, R., Oceguera-Becerra, T., Patricelli, B., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Rivière, C., Rosa-González, D., Salazar, H., Salesa, F., Sanchez, F. E., Sandoval, A., Santos, E., Schneider, M., Silich, S., Sinnis, G., Smith, A. J., Sparks, K., Springer, R. W., Taboada, I., Toale, P. A., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yodh, G. B., Younk, P. W., Zaborov, D., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We describe measurements of GeV and TeV cosmic rays with the High-Altitude Water Cherenkov Gamma-Ray Observatory, or HAWC. The measurements include the observation of the shadow of the moon; the observation of small-scale and large-scale angular clustering of the TeV cosmic rays; the prospects for measurement of transient solar events with HAWC; and the observation of Forbush decreases with the HAWC engineering array and HAWC-30., Comment: Contributions to the 33rd International Cosmic Ray Conference, Rio de Janeiro, Brazil, July 2013
Published: 2013

41. The HAWC Gamma-Ray Observatory: Dark Matter, Cosmology, and Fundamental Physics

Author: HAWC Collaboration, Abeysekara, A. U., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Barber, A. S., Baughman, B. M., Bautista-Elivar, N., Belmont, E., BenZvi, S. Y., Berley, D., Rosales, M. Bonilla, Braun, J., Caballero-Lopez, R. A., Caballero-Mora, K. S., Carramiñana, A., Castillo, M., Cotti, U., Cotzomi, J., de la Fuente, E., De León, C., DeYoung, T., Hernandez, R. Diaz, Díaz-Vélez, J. C., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Fernandez, A., Fiorino, D. W., Fraija, N., Galindo, A., Garfias, F., González, L. X., González, M. M., Goodman, J. A., Grabski, V., Gussert, M., Hampel-Arias, Z., Hui, C. M., Hüntemeyer, P., Imran, A., Iriarte, A., Karn, P., Kieda, D., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linares, E. C., Linnemann, J. T., Longo, M., Luna-GarcIa, R., Marinelli, A., Martinez, H., Martinez, O., Martínez-Castro, J., Matthews, J. A. J., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nava, J., Nellen, L., Newbold, M., Noriega-Papaqui, R., Oceguera-Becerra, T., Patricelli, B., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Rivière, C., Rosa-González, D., Salazar, H., Salesa, F., Sanchez, F. E., Sandoval, A., Santos, E., Schneider, M., Silich, S., Sinnis, G., Smith, A. J., Sparks, K., Springer, R. W., Taboada, I., Toale, P. A., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yodh, G. B., Younk, P. W., Zaborov, D., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The High-Altitude Water Cherenkov Gamma Ray Observatory (HAWC) is designed to perform a synoptic survey of the TeV sky. The high energy coverage of the experiment will enable studies of fundamental physics beyond the Standard Model, and the large field of view of the detector will enable detailed studies of cosmologically significant backgrounds and magnetic fields. We describe the sensitivity of the full HAWC array to these phenomena in five contributions shown at the 33rd International Cosmic Ray Conference in Rio de Janeiro, Brazil (July 2013)., Comment: Contributions to the 33rd International Cosmic Ray Conference, Rio de Janeiro, Brazil, July 2013
Published: 2013

42. The HAWC Gamma-Ray Observatory: Design, Calibration, and Operation

Author: HAWC Collaboration, Abeysekara, A. U., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Barber, A. S., Baughman, B. M., Bautista-Elivar, N., Belmont, E., BenZvi, S. Y., Berley, D., Rosales, M. Bonilla, Braun, J., Caballero-Lopez, R. A., Caballero-Mora, K. S., Carramiñana, A., Castillo, M., Cotti, U., Cotzomi, J., de la Fuente, E., De León, C., DeYoung, T., Hernandez, R. Diaz, Díaz-Vélez, J. C., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Fernandez, A., Fiorino, D. W., Fraija, N., Galindo, A., Garfias, F., González, L. X., González, M. M., Goodman, J. A., Grabski, V., Gussert, M., Hampel-Arias, Z., Hui, C. M., Hüntemeyer, P., Imran, A., Iriarte, A., Karn, P., Kieda, D., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linares, E. C., Linnemann, J. T., Longo, M., Luna-GarcIa, R., Marinelli, A., Martinez, H., Martinez, O., Martínez-Castro, J., Matthews, J. A. J., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nava, J., Nellen, L., Newbold, M., Noriega-Papaqui, R., Oceguera-Becerra, T., Patricelli, B., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Rivière, C., Rosa-González, D., Salazar, H., Salesa, F., Sanchez, F. E., Sandoval, A., Santos, E., Schneider, M., Silich, S., Sinnis, G., Smith, A. J., Sparks, K., Springer, R. W., Taboada, I., Toale, P. A., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yodh, G. B., Younk, P. W., Zaborov, D., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: The High-Altitude Water Cherenkov Gamma Ray Observatory (HAWC) is under construction 4100 meters above sea level at Sierra Negra, Mexico. We describe the design and cabling of the detector, the characterization of the photomultipliers, and the timing calibration system. We also outline a next-generation detector based on the water Cherenkov technique., Comment: Contributions to the 33rd International Cosmic Ray Conference, Rio de Janeiro, Brazil, July 2013
Published: 2013

43. The HAWC Gamma-Ray Observatory: Sensitivity to Steady and Transient Sources of Gamma Rays

Author: HAWC Collaboration, Abeysekara, A. U., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Barber, A. S., Baughman, B. M., Bautista-Elivar, N., Belmont, E., BenZvi, S. Y., Berley, D., Rosales, M. Bonilla, Braun, J., Caballero-Lopez, R. A., Caballero-Mora, K. S., Carramiñana, A., Castillo, M., Cotti, U., Cotzomi, J., de la Fuente, E., De León, C., DeYoung, T., Hernandez, R. Diaz, Díaz-Vélez, J. C., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Fernandez, A., Fiorino, D. W., Fraija, N., Galindo, A., Garfias, F., González, L. X., González, M. M., Goodman, J. A., Grabski, V., Gussert, M., Hampel-Arias, Z., Hui, C. M., Hüntemeyer, P., Imran, A., Iriarte, A., Karn, P., Kieda, D., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linares, E. C., Linnemann, J. T., Longo, M., Luna-GarcIa, R., Marinelli, A., Martinez, H., Martinez, O., Martínez-Castro, J., Matthews, J. A. J., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nava, J., Nellen, L., Newbold, M., Noriega-Papaqui, R., Oceguera-Becerra, T., Patricelli, B., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Rivière, C., Rosa-González, D., Salazar, H., Salesa, F., Sanchez, F. E., Sandoval, A., Santos, E., Schneider, M., Silich, S., Sinnis, G., Smith, A. J., Sparks, K., Springer, R. W., Taboada, I., Toale, P. A., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yodh, G. B., Younk, P. W., Zaborov, D., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The High-Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory is designed to record air showers produced by cosmic rays and gamma rays between 100 GeV and 100 TeV. Because of its large field of view and high livetime, HAWC is well-suited to measure gamma rays from extended sources, diffuse emission, and transient sources. We describe the sensitivity of HAWC to emission from the extended Cygnus region as well as other types of galactic diffuse emission; searches for flares from gamma-ray bursts and active galactic nuclei; and the first measurement of the Crab Nebula with HAWC-30., Comment: Contributions to the 33rd International Cosmic Ray Conference, Rio de Janeiro, Brazil, July 2013
Published: 2013

44. Sensitivity of the High Altitude Water Cherenkov Detector to Sources of Multi-TeV Gamma Rays

Author: Abeysekara, A. U., Alfaro, R., Alvarez, C., Álvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Solares, H. A. Ayala, Barber, A. S., Baughman, B. M., Bautista-Elivar, N., Belmont, E., BenZvi, S. Y., Berley, D., Rosales, M. Bonilla, Braun, J., Caballero-Lopez, R. A., Carramiñana, A., Castillo, M., Cotti, U., Cotzomi, J., de la Fuente, E., De León, C., DeYoung, T., Hernandez, R. Diaz, Diaz-Velez, J. C., Dingus, B. L., DuVernois, M. A., Ellsworth, R. W., Fernandez, A., Fiorino, D. W., Fraija, N., Galindo, A., Garcia-Luna, J. L., Garcia-Torales, G., Garfias, F., González, L. X., González, M. M., Goodman, J. A., Grabski, V., Gussert, M., Hampel-Arias, Z., Hui, C. M., Hüntemeyer, P., Imran, A., Iriarte, A., Karn, P., Kieda, D., Kunde, G. J., Lara, A., Lauer, R. J., Lee, W. H., Lennarz, D., Vargas, H. León, Linares, E. C., Linnemann, J. T., Longo, M., Luna-García, R., Marinelli, A., Martinez, O., Martínez-Castro, J., Matthews, J. A. J., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nava, J., Nellen, L., Newbold, M., Noriega-Papaqui, R., Oceguera-Becerra, T., Patricelli, B., Pelayo, R., Pérez-Pérez, E. G., Pretz, J., Rivière, C., Rosa-González, D., Salazar, H., Salesa, F., Sandoval, A., Santos, E., Schneider, M., Silich, S., Sinnis, G., Smith, A. J., Sparks, K., Springer, R. W., Taboada, I., Toale, P. A., Tollefson, K., Torres, I., Ukwatta, T. N., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I. G., Wood, J., Yodh, G. B., Younk, P. W., Zaborov, D., Zepeda, A., and Zhou, H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The High Altitude Water Cherenkov (HAWC) observatory is an array of large water Cherenkov detectors sensitive to gamma rays and hadronic cosmic rays in the energy band between 100 GeV and 100 TeV. The observatory will be used to measure high-energy protons and cosmic rays via detection of the energetic secondary particles reaching the ground when one of these particles interacts in the atmosphere above the detector. HAWC is under construction at a site 4100 meters above sea level on the northern slope of the volcano Sierra Negra, which is located in central Mexico at 19 degrees N latitude. It is scheduled for completion in 2014. In this paper we estimate the sensitivity of the HAWC instrument to point-like and extended sources of gamma rays. The source fluxes are modeled using both unbroken power laws and power laws with exponential cutoffs. HAWC, in one year, is sensitive to point sources with integral power-law spectra as low as 5x10^-13 cm^-2 sec^-1 above 2 TeV (approximately 50 mCrab) over 5 sr of the sky. This is a conservative estimate based on simple event parameters and is expected to improve as the data analysis techniques are refined. We discuss known TeV sources and the scientific contributions that HAWC can make to our understanding of particle acceleration in these sources.
Published: 2013
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45. Sensitivity of HAWC to high-mass dark matter annihilations

Author: Abeysekara, AU, Alfaro, R, Alvarez, C, Álvarez, JD, Arceo, R, Arteaga-Velázquez, JC, Solares, HA Ayala, Barber, AS, Baughman, BM, Bautista-Elivar, N, Gonzalez, J Becerra, Belmont, E, BenZvi, SY, Berley, D, Rosales, M Bonilla, Braun, J, Caballero-Lopez, RA, Caballero-Mora, KS, Carramiñana, A, Castillo, M, Cotti, U, Cotzomi, J, de la Fuente, E, De León, C, DeYoung, T, Hernandez, R Diaz, Diaz-Cruz, L, Díaz-Vélez, JC, Dingus, BL, DuVernois, MA, Ellsworth, RW, Fiorino, DW, Fraija, N, Galindo, A, Garfias, F, González, MM, Goodman, JA, Grabski, V, Gussert, M, Hampel-Arias, Z, Harding, JP, Hui, CM, Hüntemeyer, P, Imran, A, Iriarte, A, Karn, P, Kieda, D, Kunde, GJ, Lara, A, Lauer, RJ, Lee, WH, Lennarz, D, Vargas, H León, Linares, EC, Linnemann, JT, Longo, M, Luna-Garcia, R, Marinelli, A, Martinez, H, Martinez, O, Martínez-Castro, J, Matthews, JAJ, McEnery, J, Torres, E Mendoza, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nellen, L, Newbold, M, Noriega-Papaqui, R, Oceguera-Becerra, T, Patricelli, B, Pelayo, R, Pérez-Pérez, EG, Pretz, J, Rivière, C, Rosa-González, D, Ryan, J, Salazar, H, Salesa, F, Sanchez, FE, Sandoval, A, Schneider, M, Silich, S, Sinnis, G, Smith, AJ, Woodle, K Sparks, Springer, RW, Taboada, I, Toale, PA, Tollefson, K, Torres, I, Ukwatta, TN, Villaseñor, L, Weisgarber, T, Westerhoff, S, Wisher, IG, Wood, J, Yodh, GB, and Younk, PW
Subjects: astro-ph.HE, astro-ph.CO, hep-ph, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics
Abstract: The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view detector sensitive to gamma rays of 100 GeV to a few hundred TeV. Located in central Mexico at 19° North latitude and 4100 m above sea level, HAWC will observe gamma rays and cosmic rays with an array of water Cherenkov detectors. The full HAWC array is scheduled to be operational in Spring 2015. In this paper, we study the HAWC sensitivity to the gamma-ray signatures of high-mass (multi-TeV) dark matter annihilation. The HAWC observatory will be sensitive to diverse searches for dark matter annihilation, including annihilation from extended dark matter sources, the diffuse gamma-ray emission from dark matter annihilation, and gamma-ray emission from nonluminous dark matter subhalos. Here we consider the HAWC sensitivity to a subset of these sources, including dwarf galaxies, the M31 galaxy, the Virgo cluster, and the Galactic center. We simulate the HAWC response to gamma rays from these sources in several well-motivated dark matter annihilation channels. If no gamma-ray excess is observed, we show the limits HAWC can place on the dark matter cross section from these sources. In particular, in the case of dark matter annihilation into gauge bosons, HAWC will be able to detect a narrow range of dark matter masses to cross sections below thermal. HAWC should also be sensitive to nonthermal cross sections for masses up to nearly 1000 TeV. The constraints placed by HAWC on the dark matter cross section from known sources should be competitive with current limits in the mass range where HAWC has similar sensitivity. HAWC can additionally explore higher dark matter masses than are currently constrained.
Published: 2014

46. OBSERVATION OF SMALL-SCALE ANISOTROPY IN THE ARRIVAL DIRECTION DISTRIBUTION OF TeV COSMIC RAYS WITH HAWC

Author: Abeysekara, AU, Alfaro, R, Alvarez, C, Álvarez, JD, Arceo, R, Arteaga-Velázquez, JC, Solares, HA Ayala, Barber, AS, Baughman, BM, Bautista-Elivar, N, Belmont, E, BenZvi, SY, Berley, D, Rosales, M Bonilla, Braun, J, Caballero-Mora, KS, Carramiñana, A, Castillo, M, Cotti, U, Cotzomi, J, de la Fuente, E, De León, C, DeYoung, T, Hernandez, R Diaz, Díaz-Vélez, JC, Dingus, BL, DuVernois, MA, Ellsworth, RW, Fiorino, DW, Fraija, N, Galindo, A, Garfias, F, González, MM, Goodman, JA, Gussert, M, Hampel-Arias, Z, Harding, JP, Hüntemeyer, P, Hui, CM, Imran, A, Iriarte, A, Karn, P, Kieda, D, Kunde, GJ, Lara, A, Lauer, RJ, Lee, WH, Lennarz, D, Vargas, H León, Linnemann, JT, Longo, M, Luna-García, R, Malone, K, Marinelli, A, Marinelli, SS, Martinez, H, Martinez, O, Martínez-Castro, J, Matthews, JAJ, McEnery, J, Torres, E Mendoza, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nellen, L, Newbold, M, Noriega-Papaqui, R, Oceguera-Becerra, T, Patricelli, B, Pelayo, R, Pérez-Pérez, EG, Pretz, J, Rivière, C, Rosa-González, D, Ruiz-Velasco, E, Ryan, J, Salazar, H, Greus, F Salesa, Sandoval, A, Schneider, M, Sinnis, G, Smith, AJ, Woodle, K Sparks, Springer, RW, Taboada, I, Toale, PA, Tollefson, K, Torres, I, Ukwatta, TN, Villaseñor, L, Weisgarber, T, Westerhoff, S, Wisher, IG, Wood, J, Yodh, GB, Younk, PW, Zaborov, D, Zepeda, A, and Zhou, and H
Subjects: Astroparticle physics, Cosmic rays, astroparticle physics, cosmic rays, astro-ph.HE, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics
Abstract: The High-Altitude Water Cherenkov (HAWC) Observatory is sensitive to gamma rays and charged cosmic rays at TeV energies. The detector is still under construction, but data acquisition with the partially deployed detector started in 2013. An analysis of the cosmic-ray arrival direction distribution based on 4.9 × 1010 events recorded between 2013 June and 2014 February shows anisotropy at the 10-4 level on angular scales of about 10°. The HAWC cosmic-ray sky map exhibits three regions of significantly enhanced cosmic-ray flux; two of these regions were first reported by the Milagro experiment. A third region coincides with an excess recently reported by the ARGO-YBJ experiment. An angular power spectrum analysis of the sky shows that all terms up to l = 15 contribute significantly to the excesses.
Published: 2014

47. On the sensitivity of the HAWC observatory to gamma-ray bursts

Author: HAWC collaboration, Abeysekara, A. U., Aguilar, J. A., Aguilar, S., Alfaro, R., Almaraz, E., Álvarez, C., Álvarez-Romero, J. de D., Álvarez, M., Arceo, R., Arteaga-Velázquez, J. C., Badillo, C., Barber, A., Baughman, B. M., Bautista-Elivar, N., Belmont, E., Benítez, E., BenZvi, S. Y., Berley, D., Bernal, A., Bonamente, E., Braun, J., Caballero-Lopez, R., Cabrera, I., Carramiñana, A., Carrasco, L., Castillo, M., Chambers, L., Conde, R., Condreay, P., Cotti, U., Cotzomi, J., D'Olivo, J. C., de la Fuente, E., De León, C., Delay, S., Delepine, D., DeYoung, T., Diaz, L., Diaz-Cruz, L., Dingus, B. L., Duvernois, M. A., Edmunds, D., Ellsworth, R. W., Fick, B., Fiorino, D. W., Flandes, A., Fraija, N. I., Galindo, A., García-Luna, J. L., García-Torales, G., Garfias, F., González, L. X., González, M. M., Goodman, J. A., Grabski, V., Gussert, M., Guzmán-Ceron, C., Hampel-Arias, Z., Harris, T., Hays, E., Hernandez-Cervantes, L., Hüntemeyer, P. H., Imran, A., Iriarte, A., Jimenez, J. J., Karn, P., Kelley-Hoskins, N., Kieda, D., Langarica, R., Lara, A., Lauer, R., Lee, W. H., Linares, E. C., Linnemann, J. T., Longo, M., Luna-García, R., Martínez, H., Martínez, J., Martínez, L. A., Martínez, O., Martínez-Castro, J., Martos, M., Matthews, J., McEnery, J. E., Medina-Tanco, G., Mendoza-Torres, J. E., Miranda-Romagnoli, P. A., Montaruli, T., Moreno, E., Mostafa, M., Napsuciale, M., Nava, J., Nellen, L., Newbold, M., Noriega-Papaqui, R., Oceguera-Becerra, T., Tapia, A. Olmos, Orozco, V., Pérez, V., Pérez-Pérez, E. G., Perkins, J. S., Pretz, J., Ramirez, C., Ramírez, I., Rebello, D., Rentería, A., Reyes, J., Rosa-González, D., Rosado, A., Ryan, J. M., Sacahui, J. R., Salazar, H., Salesa, F., Sandoval, A., Santos, E., Schneider, M., Shoup, A., Silich, S., Sinnis, G., Smith, A. J., Sparks, K., Springer, W., Suárez, F., Suarez, N., Taboada, I., Tellez, A. F., Tenorio-Tagle, G., Tepe, A., Toale, P. A., Tollefson, K., Torres, I., Ukwatta, T. N., Valdes-Galicia, J., Vanegas, P., Vasileiou, V., Vázquez, O., Vázquez, X., Villaseñor, L., Wall, W., Walters, J. S., Warner, D., Westerhoff, S., Wisher, I. G., Wood, J., Yodh, G. B., Zaborov, D., and Zepeda, A.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present the sensitivity of HAWC to Gamma Ray Bursts (GRBs). HAWC is a very high-energy gamma-ray observatory currently under construction in Mexico at an altitude of 4100 m. It will observe atmospheric air showers via the water Cherenkov method. HAWC will consist of 300 large water tanks instrumented with 4 photomultipliers each. HAWC has two data acquisition (DAQ) systems. The main DAQ system reads out coincident signals in the tanks and reconstructs the direction and energy of individual atmospheric showers. The scaler DAQ counts the hits in each photomultiplier tube (PMT) in the detector and searches for a statistical excess over the noise of all PMTs. We show that HAWC has a realistic opportunity to observe the high-energy power law components of GRBs that extend at least up to 30 GeV, as it has been observed by Fermi LAT. The two DAQ systems have an energy threshold that is low enough to observe events similar to GRB 090510 and GRB 090902b with the characteristics observed by Fermi LAT. HAWC will provide information about the high-energy spectra of GRBs which in turn could help to understanding about e-pair attenuation in GRB jets, extragalactic background light absorption, as well as establishing the highest energy to which GRBs accelerate particles.
Published: 2011
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48. Sensitivity of the high altitude water Cherenkov detector to sources of multi-TeV gamma rays

Author: Abeysekara, AU, Alfaro, R, Alvarez, C, Álvarez, JD, Arceo, R, Arteaga-Velázquez, JC, Solares, HA Ayala, Barber, AS, Baughman, BM, Bautista-Elivar, N, Belmont, E, BenZvi, SY, Berley, D, Rosales, M Bonilla, Braun, J, Caballero-Lopez, RA, Carramiñana, A, Castillo, M, Cotti, U, Cotzomi, J, de la Fuente, E, De León, C, DeYoung, T, Hernandez, R Diaz, Diaz-Velez, JC, Dingus, BL, DuVernois, MA, Ellsworth, RW, Fernandez, A, Fiorino, DW, Fraija, N, Galindo, A, Garcia-Luna, JL, Garcia-Torales, G, Garfias, F, González, LX, González, MM, Goodman, JA, Grabski, V, Gussert, M, Hampel-Arias, Z, Hui, CM, Hüntemeyer, P, Imran, A, Iriarte, A, Karn, P, Kieda, D, Kunde, GJ, Lara, A, Lauer, RJ, Lee, WH, Lennarz, D, Vargas, H León, Linares, EC, Linnemann, JT, Longo, M, Luna-García, R, Marinelli, A, Martinez, O, Martínez-Castro, J, Matthews, JAJ, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nava, J, Nellen, L, Newbold, M, Noriega-Papaqui, R, Oceguera-Becerra, T, Patricelli, B, Pelayo, R, Pérez-Pérez, EG, Pretz, J, Rivière, C, Ryan, J, Rosa-González, D, Salazar, H, Salesa, F, Sandoval, A, Santos, E, Schneider, M, Silich, S, Sinnis, G, Smith, AJ, Sparks, K, Springer, RW, Taboada, I, Toale, PA, Tollefson, K, Torres, I, Ukwatta, TN, Villaseñor, L, Weisgarber, T, Westerhoff, S, Wisher, IG, Wood, J, Yodh, GB, Younk, PW, Zaborov, D, and Zepeda, A
Subjects: TeV gamma-ray astronomy, Water cherenkov, Cosmic ray, astro-ph.HE, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: The High Altitude Water Cherenkov (HAWC) observatory is an array of large water Cherenkov detectors sensitive to gamma rays and hadronic cosmic rays in the energy band between 100 GeV and 100 TeV. The observatory will be used to measure high-energy protons and cosmic rays via detection of the energetic secondary particles reaching the ground when one of these particles interacts in the atmosphere above the detector. HAWC is under construction at a site 4100 meters above sea level on the northern slope of the volcano Sierra Negra, which is located in central Mexico at 19 N latitude. It is scheduled for completion in 2014. In this paper we estimate the sensitivity of the HAWC instrument to point-like and extended sources of gamma rays. The source fluxes are modeled using both unbroken power laws and power laws with exponential cutoffs. HAWC, in one year, is sensitive to point sources with integral power-law spectra as low as 5×10-13 cm-2sec-1 above 2 TeV (approximately 50 mCrab) over 5 sr of the sky. This is a conservative estimate based on simple event parameters and is expected to improve as the data analysis techniques are refined. We discuss known TeV sources and the scientific contributions that HAWC can make to our understanding of particle acceleration in these sources. © 2013 Elsevier B.V. All rights reserved.
Published: 2013

49. Data acquisition architecture and online processing system for the HAWC gamma-ray observatory

Author: Abeysekara, A.U., Alfaro, R., Alvarez, C., Álvarez, J.D., Arceo, R., Arteaga-Velázquez, J.C., Ayala Solares, H.A., Barber, A.S., Baughman, B.M., Bautista-Elivar, N., Becerra Gonzalez, J., Belmont-Moreno, E., BenZvi, S.Y., Berley, D., Bonilla Rosales, M., Braun, J., Caballero-Lopez, R.A., Caballero-Mora, K.S., Carramiñana, A., Castillo, M., Cotti, U., Cotzomi, J., de la Fuente, E., De León, C., DeYoung, T., Diaz-Cruz, J., Diaz Hernandez, R., Díaz-Vélez, J.C., Dingus, B.L., DuVernois, M.A., Ellsworth, R.W., Fiorino, D.W., Fraija, N., Galindo, A., Garfias, F., González, M.M., Goodman, J.A., Grabski, V., Gussert, M., Hampel-Arias, Z., Harding, J.P., Hui, C.M., Hüntemeyer, P., Imran, A., Iriarte, A., Karn, P., Kieda, D., Kunde, G.J., Lara, A., Lauer, R.J., Lee, W.H., Lennarz, D., León Vargas, H., Linares, E.C., Linnemann, J.T., Longo Proper, M., Luna-García, R., Malone, K., Marinelli, A., Marinelli, S.S., Martinez, O., Martínez-Castro, J., Martínez-Huerta, H., Matthews, J.A.J., McEnery, J., Mendoza Torres, E., Miranda-Romagnoli, P., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Noriega-Papaqui, R., Oceguera-Becerra, T., Patricelli, B., Pelayo, R., Pérez-Pérez, E.G., Pretz, J., Rivière, C., Rosa-González, D., Ruiz-Velasco, E., Ryan, J., Salazar, H., Salesa Greus, F., Sanchez, F.E., Sandoval, A., Schneider, M., Silich, S., Sinnis, G., Smith, A.J., Sparks Woodle, K., Springer, R.W., Taboada, I., Toale, P.A., Tollefson, K., Torres, I., Ukwatta, T.N., Villaseñor, L., Weisgarber, T., Westerhoff, S., Wisher, I.G., Wood, J., Yapici, T., Yodh, G.B., Younk, P.W., Zaborov, D., Zepeda, A., and Zhou, H.
Published: 2018
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50. The HAWC Gamma-Ray Observatory: Sensitivity to Steady and Transient Sources of Gamma Rays

Author: Collaboration, HAWC, Abeysekara, AU, Alfaro, R, Alvarez, C, Álvarez, JD, Arceo, R, Arteaga-Velázquez, JC, Solares, HA Ayala, Barber, AS, Baughman, BM, Bautista-Elivar, N, Belmont, E, BenZvi, SY, Berley, D, Rosales, M Bonilla, Braun, J, Caballero-Lopez, RA, Caballero-Mora, KS, Carramiñana, A, Castillo, M, Cotti, U, Cotzomi, J, Fuente, E de la, León, C De, DeYoung, T, Hernandez, R Diaz, Díaz-Vélez, JC, Dingus, BL, DuVernois, MA, Ellsworth, RW, Fernandez, A, Fiorino, DW, Fraija, N, Galindo, A, Garfias, F, González, LX, González, MM, Goodman, JA, Grabski, V, Gussert, M, Hampel-Arias, Z, Hui, CM, Hüntemeyer, P, Imran, A, Iriarte, A, Karn, P, Kieda, D, Kunde, GJ, Lara, A, Lauer, RJ, Lee, WH, Lennarz, D, Vargas, H León, Linares, EC, Linnemann, JT, Longo, M, Luna-GarcIa, R, Marinelli, A, Martinez, H, Martinez, O, Martínez-Castro, J, Matthews, JAJ, Miranda-Romagnoli, P, Moreno, E, Mostafá, M, Nava, J, Nellen, L, Newbold, M, Noriega-Papaqui, R, Oceguera-Becerra, T, Patricelli, B, Pelayo, R, Pérez-Pérez, EG, Pretz, J, Rivière, C, Rosa-González, D, Salazar, H, Salesa, F, Sanchez, FE, Sandoval, A, Santos, E, Schneider, M, Silich, S, Sinnis, G, Smith, AJ, Sparks, K, Springer, RW, Taboada, I, Toale, PA, Tollefson, K, Torres, I, Ukwatta, TN, Villaseñor, L, Weisgarber, T, Westerhoff, S, Wisher, IG, Wood, J, Yodh, GB, Younk, PW, and Zaborov, D
Subjects: astro-ph.HE
Abstract: The High-Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory is designed torecord air showers produced by cosmic rays and gamma rays between 100 GeV and100 TeV. Because of its large field of view and high livetime, HAWC iswell-suited to measure gamma rays from extended sources, diffuse emission, andtransient sources. We describe the sensitivity of HAWC to emission from theextended Cygnus region as well as other types of galactic diffuse emission;searches for flares from gamma-ray bursts and active galactic nuclei; and thefirst measurement of the Crab Nebula with HAWC-30.
Published: 2013

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