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A search for enhanced very high energy GAMMA-RAY emission from the 2013 march crab nebula flare
(2014)
Aliu, E. ; Archambault, S. ; Aune, T. ; Benbow, W. ; Berger, K. ; Bird, R. ; Bouvier, A. ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cerruti, M. ; Chen, Xuhui ; Ciupik, L. ; Connolly, M. P. ; Cui, W. ; Dumm, J. ; Errando, M. ; Falcone, A. ; Federici, Simone ; Feng, Q. ; Finley, J. P. ; Fortin, P. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gillanders, G. H. ; Griffin, S. ; Griffiths, S. T. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Kaaret, P. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krennrich, F. ; Kumar, S. ; Lang, M. J. ; Lyutikov, M. ; Maier, G. ; McArthur, S. ; McCann, A. ; Meagher, K. ; Millis, J. ; Moriarty, P. ; Mukherjee, R. ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Perkins, J. S. ; Pohl, M. ; Popkow, A. ; Quinn, J. ; Ragan, K. ; Rajotte, J. ; Reyes, L. C. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Sembroski, G. H. ; Sheidaei, F. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Theiling, M. ; Tucci, J. V. ; Tyler, J. ; Varlotta, A. ; Wakely, S. P. ; Weekes, T. C. ; Weinstein, A. ; Welsing, R. ; Williams, D. A. ; Zajczyk, A. ; Zitzer, B.
In 2013 March, a flaring episode from the Crab Nebula lasting similar to 2 weeks was detected by Fermi-LAT (Large Area Telescope on board the Fermi Gamma-ray Space Telescope). The Very Energetic Radiation Imaging Telescope Array System (VERITAS) provides simultaneous observations throughout this period. During the flare, Fermi-LAT detected a 20 fold increase in flux above the average synchrotron flux >100 MeV seen from the Crab Nebula. Simultaneous measurements with VERITAS are consistent with the non-variable long-term average Crab Nebula flux at TeV energies. Assuming a linear correlation between the very high energy flux change >1 TeV and the flux change seen in the Fermi-LAT band >100 MeV during the period of simultaneous observations, the linear correlation factor can be constrained to be at most 8.6 x 10(-3) with 95% confidence.
Aliu, E. ; Archambault, S. ; Arlen, T. ; Aune, T. ; Behera, B. ; Beilicke, M. ; Benbow, W. ; Berger, K. ; Bird, R. ; Bouvier, A. ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cerruti, M. ; Chen, Xuhui ; Ciupik, L. ; Connolly, M. P. ; Cui, W. ; Duke, C. ; Dumm, J. ; Errando, M. ; Falcone, A. ; Federici, S. ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Fortin, P. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gillanders, G. H. ; Griffin, S. ; Griffiths, S. T. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Johnson, C. A. ; Kaaret, P. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Madhavan, A. S. ; Maier, G. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; Meagher, K. ; Millis, J. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Perkins, J. S. ; Pohl, M. ; Popkow, A. ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Sembroski, G. H. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Theiling, M. ; Varlotta, A. ; Vassiliev, V. V. ; Vincent, S. ; Wakely, S. P. ; Weekes, T. C. ; Weinstein, A. ; Welsing, R. ; Williams, D. A. ; Zajczyk, A. ; Zitzer, B.
Arlen, T. ; Aune, T. ; Beilicke, M. ; Benbow, W. ; Bouvier, A. ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cannon, A. ; Cesarini, A. ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Cui, W. ; Dickherber, R. ; Dumm, J. ; Falcone, A. ; Federici, S. ; Feng, Q. ; Finley, J. P. ; Finnegan, G. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gall, D. ; Godambe, S. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Holder, J. ; Huan, H. ; Hughes, G. ; Humensky, T. B. ; Imran, A. ; Kaaret, P. ; Karlsson, N. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lee, K. ; Madhavan, A. S. ; Maier, G. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; Moriarty, P. ; Mukherjee, R. ; Nelson, T. ; de Bhroithe, A. O'Faolain ; Ong, R. A. ; Orr, M. ; Otte, A. N. ; Park, N. ; Perkins, J. S. ; Pohl, Martin ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Roache, E. ; Ruppel, J. ; Saxon, D. B. ; Schroedter, M. ; Sembroski, G. H. ; Skole, C. ; Smith, A. W. ; Telezhinsky, Igor O. ; Tesic, G. ; Theiling, M. ; Thibadeau, S. ; Tsurusaki, K. ; Varlotta, A. ; Vivier, M. ; Wakely, S. P. ; Ward, J. E. ; Weinstein, A. ; Welsing, R. ; Williams, D. A. ; Zitzer, B. ; Pfrommer, C. ; Pinzke, A.
Observations of radio halos and relics in galaxy clusters indicate efficient electron acceleration. Protons should likewise be accelerated and, on account of weak energy losses, can accumulate, suggesting that clusters may also be sources of very high energy (VHE; E > 100 GeV) gamma-ray emission. We report here on VHE gamma-ray observations of the Coma galaxy cluster with the VERITAS array of imaging Cerenkov telescopes, with complementing Fermi Large Area Telescope observations at GeV energies. No significant gamma-ray emission from the Coma Cluster was detected. Integral flux upper limits at the 99% confidence level were measured to be on the order of (2-5) x 10(-8) photonsm(-2) s(-1) (VERITAS, >220 GeV) and similar to 2 x 10(-6) photonsm(-2) s(-1) (Fermi, 1-3GeV), respectively. We use the gamma-ray upper limits to constrain cosmic rays (CRs) and magnetic fields in Coma. Using an analytical approach, the CR-to-thermal pressure ratio is constrained to be < 16% from VERITAS data and <1.7% from Fermi data (averaged within the virial radius). These upper limits are starting to constrain the CR physics in self-consistent cosmological cluster simulations and cap the maximum CR acceleration efficiency at structure formation shocks to be <50%. Alternatively, this may argue for non-negligible CR transport processes such as CR streaming and diffusion into the outer cluster regions. Assuming that the radio-emitting electrons of the Coma halo result from hadronic CR interactions, the observations imply a lower limit on the central magnetic field in Coma of similar to(2-5.5) mu G, depending on the radial magnetic field profile and on the gamma-ray spectral index. Since these values are below those inferred by Faraday rotation measurements in Coma (for most of the parameter space), this renders the hadronic model a very plausible explanation of the Coma radio halo. Finally, since galaxy clusters are dark matter (DM) dominated, the VERITAS upper limits have been used to place constraints on the thermally averaged product of the total self-annihilation cross section and the relative velocity of the DM particles, <sigma nu >.
Actis, M. ; Agnetta, G. ; Aharonian, Felix A. ; Akhperjanian, A. G. ; Aleksic, J. ; Aliu, E. ; Allan, D. ; Allekotte, I. ; Antico, F. ; Antonelli, L. A. ; Antoranz, P. ; Aravantinos, A. ; Arlen, T. ; Arnaldi, H. ; Artmann, S. ; Asano, K. ; Asorey, H. G. ; Baehr, J. ; Bais, A. ; Baixeras, C. ; Bajtlik, S. ; Balis, D. ; Bamba, A. ; Barbier, C. ; Barcelo, M. ; Barnacka, Anna ; Barnstedt, Jürgen ; de Almeida, U. Barres ; Barrio, J. A. ; Basso, S. ; Bastieri, D. ; Bauer, C. ; Becerra Gonzalez, J. ; Becherini, Yvonne ; Bechtol, K. C. ; Becker, J. ; Beckmann, Volker ; Bednarek, W. ; Behera, B. ; Beilicke, M. ; Belluso, M. ; Benallou, M. ; Benbow, W. ; Berdugo, J. ; Berger, K. ; Bernardino, T. ; Bernlöhr, K. ; Biland, A. ; Billotta, S. ; Bird, T. ; Birsin, E. ; Bissaldi, E. ; Blake, S. ; Blanch Bigas, O. ; Bobkov, A. A. ; Bogacz, L. ; Bogdan, M. ; Boisson, Catherine ; Boix Gargallo, J. ; Bolmont, J. ; Bonanno, G. ; Bonardi, A. ; Bonev, T. ; Borkowski, Janett ; Botner, O. ; Bottani, A. ; Bourgeat, M. ; Boutonnet, C. ; Bouvier, A. ; Brau-Nogue, S. ; Braun, I. ; Bretz, T. ; Briggs, M. S. ; Brun, Pierre ; Brunetti, L. ; Buckley, H. ; Bugaev, V. ; Buehler, R. ; Bulik, Tomasz ; Busetto, G. ; Buson, S. ; Byrum, K. ; Cailles, M. ; Cameron, R. A. ; Canestrari, R. ; Cantu, S. ; Carmona, E. ; Carosi, A. ; Carr, John ; Carton, P. H. ; Casiraghi, M. ; Castarede, H. ; Catalano, O. ; Cavazzani, S. ; Cazaux, S. ; Cerruti, B. ; Cerruti, M. ; Chadwick, M. ; Chiang, J. ; Chikawa, M. ; Cieslar, M. ; Ciesielska, M. ; Cillis, A. N. ; Clerc, C. ; Colin, P. ; Colome, J. ; Compin, M. ; Conconi, P. ; Connaughton, V. ; Conrad, Jan ; Contreras, J. L. ; Coppi, P. ; Corlier, M. ; Corona, P. ; Corpace, O. ; Corti, D. ; Cortina, J. ; Costantini, H. ; Cotter, G. ; Courty, B. ; Couturier, S. ; Covino, S. ; Croston, J. ; Cusumano, G. ; Daniel, M. K. ; Dazzi, F. ; Deangelis, A. ; de Cea del Pozo, E. ; Dal Pino, E. M. de Gouveia ; de Jager, O. ; de la Calle Perez, I. ; De La Vega, G. ; De Lotto, B. ; de Naurois, M. ; Wilhelmi, E. de Ona ; de Souza, V. ; Decerprit, B. ; Deil, C. ; Delagnes, E. ; Deleglise, G. ; Delgado, C. ; Dettlaff, T. ; Di Paolo, A. ; Di Pierro, F. ; Diaz, C. ; Dick, J. ; Dickinson, H. ; Digel, S. W. ; Dimitrov, D. ; Disset, G. ; Djannati-Ataï, A. ; Doert, M. ; Domainko, W. ; Dorner, D. ; Doro, M. ; Dournaux, J. -L. ; Dravins, D. ; Drury, L. ; Dubois, F. ; Dubois, R. ; Dubus, G. ; Dufour, C. ; Durand, D. ; Dyks, J. ; Dyrda, M. ; Edy, E. ; Egberts, Kathrin ; Eleftheriadis, C. ; Elles, S. ; Emmanoulopoulos, D. ; Enomoto, R. ; Ernenwein, J. -P. ; Errando, M. ; Etchegoyen, A. ; Falcone, A. D. ; Farakos, K. ; Farnier, C. ; Federici, S. ; Feinstein, F. ; Ferenc, D. ; Fillin-Martino, E. ; Fink, D. ; Finley, C. ; Finley, J. P. ; Firpo, R. ; Florin, D. ; Foehr, C. ; Fokitis, E. ; Font, Ll. ; Fontaine, G. ; Fontana, A. ; Foerster, A. ; Fortson, L. ; Fouque, N. ; Fransson, C. ; Fraser, G. W. ; Fresnillo, L. ; Fruck, C. ; Fujita, Y. ; Fukazawa, Y. ; Funk, S. ; Gaebele, W. ; Gabici, S. ; Gadola, A. ; Galante, N. ; Gallant, Y. ; Garcia, B. ; Garcia Lopez, R. J. ; Garrido, D. ; Garrido, L. ; Gascon, D. ; Gasq, C. ; Gaug, M. ; Gaweda, J. ; Geffroy, N. ; Ghag, C. ; Ghedina, A. ; Ghigo, M. ; Gianakaki, E. ; Giarrusso, S. ; Giavitto, G. ; Giebels, B. ; Giro, E. ; Giubilato, P. ; Glanzman, T. ; Glicenstein, J. -F. ; Gochna, M. ; Golev, V. ; Gomez Berisso, M. ; Gonzalez, A. ; Gonzalez, F. ; Granena, F. ; Graciani, R. ; Granot, J. ; Gredig, R. ; Green, A. ; Greenshaw, T. ; Grimm, O. ; Grube, J. ; Grudzinska, M. ; Grygorczuk, J. ; Guarino, V. ; Guglielmi, L. ; Guilloux, F. ; Gunji, S. ; Gyuk, G. ; Hadasch, D. ; Haefner, D. ; Hagiwara, R. ; Hahn, J. ; Hallgren, A. ; Hara, S. ; Hardcastle, M. J. ; Hassan, T. ; Haubold, T. ; Hauser, M. ; Hayashida, M. ; Heller, R. ; Henri, G. ; Hermann, G. ; Herrero, A. ; Hinton, James Anthony ; Hoffmann, D. ; Hofmann, W. ; Hofverberg, P. ; Horns, D. ; Hrupec, D. ; Huan, H. ; Huber, B. ; Huet, J. -M. ; Hughes, G. ; Hultquist, K. ; Humensky, T. B. ; Huppert, J. -F. ; Ibarra, A. ; Illa, J. M. ; Ingjald, J. ; Inoue, S. ; Inoue, Y. ; Ioka, K. ; Jablonski, C. ; Jacholkowska, A. ; Janiak, M. ; Jean, P. ; Jensen, H. ; Jogler, T. ; Jung, I. ; Kaaret, P. ; Kabuki, S. ; Kakuwa, J. ; Kalkuhl, C. ; Kankanyan, R. ; Kapala, M. ; Karastergiou, A. ; Karczewski, M. ; Karkar, S. ; Karlsson, N. ; Kasperek, J. ; Katagiri, H. ; Katarzynski, K. ; Kawanaka, N. ; Kedziora, B. ; Kendziorra, E. ; Khelifi, B. ; Kieda, D. ; Kifune, T. ; Kihm, T. ; Klepser, S. ; Kluzniak, W. ; Knapp, J. ; Knappy, A. R. ; Kneiske, T. ; Knoedlseder, J. ; Koeck, F. ; Kodani, K. ; Kohri, K. ; Kokkotas, K. ; Komin, N. ; Konopelko, A. ; Kosack, K. ; Kossakowski, R. ; Kostka, P. ; Kotula, J. ; Kowal, G. ; Koziol, J. ; Kraehenbuehl, T. ; Krause, J. ; Krawczynski, H. ; Krennrich, F. ; Kretzschmann, A. ; Kubo, H. ; Kudryavtsev, V. A. ; Kushida, J. ; La Barbera, N. ; La Parola, V. ; La Rosa, G. ; Lopez, A. ; Lamanna, G. ; Laporte, P. ; Lavalley, C. ; Le Flour, T. ; Le Padellec, A. ; Lenain, J. -P. ; Lessio, L. ; Lieunard, B. ; Lindfors, E. ; Liolios, A. ; Lohse, T. ; Lombardi, S. ; Lopatin, A. ; Lorenz, E. ; Lubinski, P. ; Luz, O. ; Lyard, E. ; Maccarone, M. C. ; Maccarone, T. ; Maier, G. ; Majumdar, P. ; Maltezos, S. ; Malkiewicz, P. ; Mana, C. ; Manalaysay, A. ; Maneva, G. ; Mangano, A. ; Manigot, P. ; Marin, J. ; Mariotti, M. ; Markoff, S. ; Martinez, G. ; Martinez, M. ; Mastichiadis, A. ; Matsumoto, H. ; Mattiazzo, S. ; Mazin, D. ; McComb, T. J. L. ; McCubbin, N. ; McHardy, I. ; Medina, C. ; Melkumyan, D. ; Mendes, A. ; Mertsch, P. ; Meucci, M. ; Michalowski, J. ; Micolon, P. ; Mineo, T. ; Mirabal, N. ; Mirabel, F. ; Miranda, J. M. ; Mirzoyan, R. ; Mizuno, T. ; Moal, B. ; Moderski, R. ; Molinari, E. ; Monteiro, I. ; Moralejo, A. ; Morello, C. ; Mori, K. ; Motta, G. ; Mottez, F. ; Moulin, E. ; Mukherjee, R. ; Munar, P. ; Muraishi, H. ; Murase, K. ; Murphy, A. Stj. ; Nagataki, S. ; Naito, T. ; Nakamori, T. ; Nakayama, K. ; Naumann, C. L. ; Naumann, D. ; Nayman, P. ; Nedbal, D. ; Niedzwiecki, A. ; Niemiec, J. ; Nikolaidis, A. ; Nishijima, K. ; Nolan, S. J. ; Nowak, N. ; O'Brien, P. T. ; Ochoa, I. ; Ohira, Y. ; Ohishi, M. ; Ohka, H. ; Okumura, A. ; Olivetto, C. ; Ong, R. A. ; Orito, R. ; Orr, M. ; Osborne, J. P. ; Ostrowski, M. ; Otero, L. ; Otte, A. N. ; Ovcharov, E. ; Oya, I. ; Ozieblo, A. ; Paiano, S. ; Pallota, J. ; Panazol, J. L. ; Paneque, D. ; Panter, M. ; Paoletti, R. ; Papyan, G. ; Paredes, J. M. ; Pareschi, G. ; Parsons, R. D. ; Arribas, M. Paz ; Pedaletti, G. ; Pepato, A. ; Persic, M. ; Petrucci, P. O. ; Peyaud, B. ; Piechocki, W. ; Pita, S. ; Pivato, G. ; Platos, L. ; Platzer, R. ; Pogosyan, L. ; Pohl, Martin ; Pojmanski, G. ; Ponz, J. D. ; Potter, W. ; Prandini, E. ; Preece, R. ; Prokoph, H. ; Puehlhofer, G. ; Punch, M. ; Quel, E. ; Quirrenbach, A. ; Rajda, P. ; Rando, R. ; Rataj, M. ; Raue, M. ; Reimann, C. ; Reimann, O. ; Reimer, A. ; Reimer, O. ; Renaud, M. ; Renner, S. ; Reymond, J. -M. ; Rhode, W. ; Ribo, M. ; Ribordy, M. ; Rico, J. ; Rieger, F. ; Ringegni, P. ; Ripken, J. ; Ristori, P. ; Rivoire, S. ; Rob, L. ; Rodriguez, S. ; Roeser, U. ; Romano, Patrizia ; Romero, G. E. ; Rosier-Lees, S. ; Rovero, A. C. ; Roy, F. ; Royer, S. ; Rudak, B. ; Rulten, C. B. ; Ruppel, J. ; Russo, F. ; Ryde, F. ; Sacco, B. ; Saggion, A. ; Sahakian, V. ; Saito, K. ; Saito, T. ; Sakaki, N. ; Salazar, E. ; Salini, A. ; Sanchez, F. ; Sanchez Conde, M. A. ; Santangelo, A. ; Santos, E. M. ; Sanuy, A. ; Sapozhnikov, L. ; Sarkar, S. ; Scalzotto, V. ; Scapin, V. ; Scarcioffolo, M. ; Schanz, T. ; Schlenstedt, S. ; Schlickeiser, R. ; Schmidt, T. ; Schmoll, J. ; Schroedter, M. ; Schultz, C. ; Schultze, J. ; Schulz, A. ; Schwanke, U. ; Schwarzburg, S. ; Schweizer, T. ; Seiradakis, J. ; Selmane, S. ; Seweryn, K. ; Shayduk, M. ; Shellard, R. C. ; Shibata, T. ; Sikora, M. ; Silk, J. ; Sillanpaa, A. ; Sitarek, J. ; Skole, C. ; Smith, N. ; Sobczynska, D. ; Sofo Haro, M. ; Sol, H. ; Spanier, F. ; Spiga, D. ; Spyrou, S. ; Stamatescu, V. ; Stamerra, A. ; Starling, R. L. C. ; Stawarz, L. ; Steenkamp, R. ; Stegmann, Christian ; Steiner, S. ; Stergioulas, N. ; Sternberger, R. ; Stinzing, F. ; Stodulski, M. ; Straumann, U. ; Suarez, A. ; Suchenek, M. ; Sugawara, R. ; Sulanke, K. H. ; Sun, S. ; Supanitsky, A. D. ; Sutcliffe, P. ; Szanecki, M. ; Szepieniec, T. ; Szostek, A. ; Szymkowiak, A. ; Tagliaferri, G. ; Tajima, H. ; Takahashi, H. ; Takahashi, K. ; Takalo, L. ; Takami, H. ; Talbot, R. G. ; Tam, P. H. ; Tanaka, M. ; Tanimori, T. ; Tavani, M. ; Tavernet, J. -P. ; Tchernin, C. ; Tejedor, L. A. ; Telezhinsky, Igor O. ; Temnikov, P. ; Tenzer, C. ; Terada, Y. ; Terrier, R. ; Teshima, M. ; Testa, V. ; Tibaldo, L. ; Tibolla, O. ; Tluczykont, M. ; Peixoto, C. J. Todero ; Tokanai, F. ; Tokarz, M. ; Toma, K. ; Torres, D. F. ; Tosti, G. ; Totani, T. ; Toussenel, F. ; Vallania, P. ; Vallejo, G. ; van der Walt, J. ; van Eldik, C. ; Vandenbroucke, J. ; Vankov, H. ; Vasileiadis, G. ; Vassiliev, V. V. ; Vegas, I. ; Venter, L. ; Vercellone, S. ; Veyssiere, C. ; Vialle, J. P. ; Videla, M. ; Vincent, P. ; Vink, J. ; Vlahakis, N. ; Vlahos, L. ; Vogler, P. ; Vollhardt, A. ; Volpe, F. ; Von Gunten, H. P. ; Vorobiov, S. ; Wagner, S. ; Wagner, R. M. ; Wagner, B. ; Wakely, S. P. ; Walter, P. ; Walter, R. ; Warwick, R. ; Wawer, P. ; Wawrzaszek, R. ; Webb, N. ; Wegner, P. ; Weinstein, A. ; Weitzel, Q. ; Welsing, R. ; Wetteskind, H. ; White, R. ; Wierzcholska, A. ; Wilkinson, M. I. ; Williams, D. A. ; Winde, M. ; Wischnewski, R. ; Wisniewski, L. ; Wolczko, A. ; Wood, M. ; Xiong, Q. ; Yamamoto, T. ; Yamaoka, K. ; Yamazaki, R. ; Yanagita, S. ; Yoffo, B. ; Yonetani, M. ; Yoshida, A. ; Yoshida, T. ; Yoshikoshi, T. ; Zabalza, V. ; Zagdanski, A. ; Zajczyk, A. ; Zdziarski, A. ; Zech, Alraune ; Zietara, K. ; Ziolkowski, P. ; Zitelli, V. ; Zychowski, P.
Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.
Aliu, E. ; Arlen, T. ; Aune, T. ; Beilicke, M. ; Benbow, W. ; Bouvier, A. ; Bradbury, S. M. ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cannon, A. ; Cesarini, A. ; Christiansen, J. L. ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Cui, W. ; Dickherber, R. ; Duke, C. ; Errando, M. ; Falcone, A. ; Finley, J. P. ; Finnegan, G. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gall, D. ; Gibbs, K. ; Gillanders, G. H. ; Godambe, S. ; Griffin, S. ; Grube, J. ; Guenette, R. ; Gyuk, G. ; Hanna, D. ; Holder, J. ; Huan, H. ; Hughes, G. ; Hui, C. M. ; Humensky, T. B. ; Imran, A. ; Kaaret, P. ; Karlsson, N. ; Kertzman, M. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Lyutikov, M. ; Madhavan, A. S. ; Maier, G. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; McCutcheon, M. ; Moriarty, P. ; Mukherjee, R. ; Nunez, P. ; Ong, R. A. ; Orr, M. ; Otte, A. N. ; Park, N. ; Perkins, J. S. ; Pizlo, F. ; Pohl, Martin ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Roache, E. ; Rose, H. J. ; Ruppel, J. ; Saxon, D. B. ; Schroedter, M. ; Sembroski, G. H. ; Sentuerk, G. D. ; Smith, A. W. ; Staszak, D. ; Tesic, G. ; Theiling, M. ; Thibadeau, S. ; Tsurusaki, K. ; Tyler, J. ; Varlotta, A. ; Vassiliev, V. V. ; Vincent, S. ; Vivier, M. ; Wakely, S. P. ; Ward, J. E. ; Weekes, T. C. ; Weinstein, A. ; Weisgarber, T. ; Williams, D. A. ; Zitzer, B.
We report the detection of pulsed gamma rays from the Crab pulsar at energies above 100 giga-electron volts (GeV) with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) array of atmospheric Cherenkov telescopes. The detection cannot be explained on the basis of current pulsar models. The photon spectrum of pulsed emission between 100 mega-electron volts and 400 GeV is described by a broken power law that is statistically preferred over a power law with an exponential cutoff. It is unlikely that the observation can be explained by invoking curvature radiation as the origin of the observed gamma rays above 100 GeV. Our findings require that these gamma rays be produced more than 10 stellar radii from the neutron star.
Archambault, S. ; Arlen, T. ; Aune, T. ; Behera, B. ; Beilicke, M. ; Benbow, W. ; Bird, R. ; Bouvier, A. ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cesarini, A. ; Ciupik, L. ; Connolly, M. P. ; Cui, W. ; Errando, M. ; Falcone, A. ; Federici, Simone ; Feng, Q. ; Finley, J. P. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gall, D. ; Gillanders, G. H. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Kaaret, P. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Kumar, S. ; Lang, M. J. ; Madhavan, A. S. ; Maier, G. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; Millis, J. ; Moriarty, P. ; Mukherjee, R. ; de Bhroithe, A. O'Faolain ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Perkins, J. S. ; Pohl, Martin ; Popkow, A. ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Saxon, D. B. ; Sembroski, G. H. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Theiling, M. ; Varlotta, A. ; Vassiliev, V. V. ; Vincent, S. ; Wakely, S. P. ; Weekes, T. C. ; Weinstein, A. ; Welsing, R. ; Williams, D. A. ; Zitzer, B. ; Boettcher, Markus ; Fegan, S. J. ; Fortin, P. ; Halpern, J. P. ; Kovalev, Y. Y. ; Lister, M. L. ; Liu, J. ; Pushkarev, A. B. ; Smith, P. S.
We report the detection of a new TeV gamma-ray source, VER J0521+211, based on observations made with the VERITAS imaging atmospheric Cherenkov Telescope Array. These observations were motivated by the discovery of a cluster of >30 GeV photons in the first year of Fermi Large Area Telescope observations. VER J0521+211 is relatively bright at TeV energies, with a mean photon flux of (1.93 +/- 0.13(stat) +/- 0.78(sys)) x 10(-11) cm(-2) s(-1) above 0.2 TeV during the period of the VERITAS observations. The source is strongly variable on a daily timescale across all wavebands, from optical to TeV, with a peak flux corresponding to similar to 0.3 times the steady Crab Nebula flux at TeV energies. Follow-up observations in the optical and X-ray bands classify the newly discovered TeV source as a BL Lac-type blazar with uncertain redshift, although recent measurements suggest z = 0.108. VER J0521+211 exhibits all the defining properties of blazars in radio, optical, X-ray, and gamma-ray wavelengths.
Aliu, E. ; Archambault, S. ; Arlen, T. ; Aune, T. ; Beilicke, M. ; Benbow, W. ; Bouvier, A. ; Buckley, J. H. ; Bugaev, V. ; Cesarini, A. ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Cui, W. ; Dickherber, R. ; Duke, C. ; Dumm, J. ; Dwarkadas, Vikram V. ; Errando, M. ; Falcone, A. ; Federici, S. ; Feng, Q. ; Finley, J. P. ; Finnegan, G. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gall, D. ; Gillanders, G. H. ; Godambe, S. ; Gotthelf, E. V. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Kaaret, P. ; Kargaltsev, O. ; Karlsson, N. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Lee, K. ; Madhavan, A. S. ; Maier, G. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; Moriarty, P. ; Mukherjee, R. ; Nelson, T. ; de Bhroithe, A. O&rsquo ; Faolain ; Ong, R. A. ; Orr, M. ; Otte, A. N. ; Park, N. ; Perkins, J. S. ; Pohl, M. ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Roache, E. ; Roberts, M. ; Saxon, D. B. ; Schroedter, M. ; Sembroski, G. H. ; Slane, P. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Tesic, G. ; Theiling, M. ; Thibadeau, S. ; Tsurusaki, K. ; Tyler, J. ; Varlotta, A. ; Vassiliev, V. V. ; Vincent, S. ; Vivier, M. ; Wakely, S. P. ; Weekes, T. C. ; Weinstein, A. ; Welsing, R. ; Williams, D. A. ; Zitzer, B.
We report the discovery of TeV gamma-ray emission coincident with the shell-type radio supernova remnant (SNR) CTA 1 using the VERITAS gamma-ray observatory. The source, VER J0006+729, was detected as a 6.5 standard deviation excess over background and shows an extended morphology, approximated by a two-dimensional Gaussian of semimajor (semiminor) axis 0.degrees 30 (0.degrees 24) and a centroid 5’ from the Fermi gamma-ray pulsar PSR J0007+7303 and its X-ray pulsar wind nebula (PWN). The photon spectrum is well described by a power-law dN/dE = N-0(E/3 TeV)(-Gamma), with a differential spectral index of Gamma = 2.2 +/- 0.2(stat) +/- 0.3(sys), and normalization N-0 = (9.1 +/- 1.3(stat) +/- 1.7(sys)) x 10(-14) cm(-2) s(-1) TeV-1. The integral flux, F-gamma = 4.0 x 10(-12) erg cm(-2) s(-1) above 1 TeV, corresponds to 0.2% of the pulsar spin-down power at 1.4 kpc. The energetics, colocation with the SNR, and the relatively small extent of the TeV emission strongly argue for the PWN origin of the TeV photons. We consider the origin of the TeV emission in CTA 1.
tAliu, E. ; Archambault, S. ; Arlen, T. ; Aune, T. ; Beilicke, M. ; Benbow, W. ; Bird, R. ; Bouvier, A. ; Bradbury, S. M. ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cannon, A. ; Cesarini, A. ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Cui, W. ; Dickherber, R. ; Duke, C. ; Dumm, J. ; Dwarkadas, Vikram V. ; Errando, M. ; Falcone, A. ; Federici, Simone ; Feng, Q. ; Finley, J. P. ; Finnegan, G. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gall, D. ; Gillanders, G. H. ; Godambe, S. ; Gotthelf, E. V. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Holder, J. ; Huan, H. ; Hughes, G. ; Humensky, T. B. ; Kaaret, P. ; Karlsson, N. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Lee, K. ; Madhavan, A. S. ; Maier, G. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; Millis, J. ; Moriarty, P. ; Mukherjee, R. ; Nelson, T. ; de Bhroithe, A. O'Faolain ; Ong, R. A. ; Orr, M. ; Otte, A. N. ; Pandel, D. ; Park, N. ; Perkins, J. S. ; Pohl, Martin ; Popkow, A. ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Roache, E. ; Rose, H. J. ; Ruppel, Jens ; Saxon, D. B. ; Schroedter, M. ; Sembroski, G. H. ; Sentuerk, G. D. ; Skole, C. ; Telezhinsky, Igor O. ; Tesic, G. ; Theiling, M. ; Thibadeau, S. ; Tsurusaki, K. ; Tyler, J. ; Varlotta, A. ; Vassiliev, V. V. ; Vincent, S. ; Wakely, S. P. ; Ward, J. E. ; Weekes, T. C. ; Weinstein, A. ; Weisgarber, T. ; Welsing, R. ; Williams, D. A. ; Zitzer, B.
We report the discovery of an unidentified, extended source of very-high-energy gamma-ray emission, VER J2019+407, within the radio shell of the supernova remnant SNR G78.2+2.1, using 21.4 hr of data taken by the VERITAS gamma-ray observatory in 2009. These data confirm the preliminary indications of gamma-ray emission previously seen in a two-year (2007-2009) blind survey of the Cygnus region by VERITAS. VER J2019+407, which is detected at a post-trials significance of 7.5 standard deviations in the 2009 data, is localized to the northwestern rim of the remnant in a region of enhanced radio and X-ray emission. It has an intrinsic extent of 0 degrees.23 +/- 0 degrees.03(stat-0 degrees.02sys)(+0 degrees.04) and its spectrum is well-characterized by a differential power law (dN/dE = N-0 x (E/TeV)-Gamma) with a photon index of Gamma = 2.37 +/- 0.14(stat) +/- 0.20(sys) and a flux normalization of N-0 = 1.5 +/- 0.2(stat) +/- 0.4(sys) x 10(-12) photon TeV-1 cm(-2) s(-1). This yields an integral flux of 5.2 +/- 0.8(stat) +/- 1.4(sys) x 10(-12) photon cm(-2) s(-1) above 320 GeV, corresponding to 3.7% of the Crab Nebula flux. We consider the relationship of the TeV gamma-ray emission with the GeV gamma-ray emission seen from SNR G78.2+2.1 as well as that seen from a nearby cocoon of freshly accelerated cosmic rays. Multiple scenarios are considered as possible origins for the TeV gamma-ray emission, including hadronic particle acceleration at the SNR shock.
Aliu, E. ; Archambault, S. ; Arlen, T. ; Aune, T. ; Beilicke, M. ; Benbow, W. ; Boettcher, Markus ; Bouvier, A. ; Bradbury, S. M. ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cannon, A. ; Cesarini, A. ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Coppi, P. ; Cui, W. ; Decerprit, G. ; Dickherber, R. ; Dumm, J. ; Errando, Manel ; Falcone, A. ; Feng, Q. ; Finley, J. P. ; Finnegan, G. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gall, D. ; Godambe, S. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Hawkins, K. ; Holder, J. ; Huan, H. ; Hughes, G. ; Humensky, T. B. ; Kaaret, P. ; Karlsson, N. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Lee, K. ; Madhavan, A. S. ; Maier, G. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; Moriarty, P. ; Mukherjee, Reshmi ; Ong, R. A. ; Orr, M. ; Otte, A. N. ; Palma, N. ; Park, N. ; Perkins, J. S. ; Pichel, A. ; Pohl, Martin ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Roache, E. ; Rose, H. J. ; Ruppel, J. ; Saxon, D. B. ; Schroedter, M. ; Sembroski, G. H. ; Sentuerk, G. D. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Tesic, G. ; Theiling, M. ; Thibadeau, S. ; Tsurusaki, K. ; Varlotta, A. ; Vivier, M. ; Wakely, S. P. ; Ward, J. E. ; Weekes, T. C. ; Weinstein, A. ; Weisgarber, T. ; Williams, D. A. ; Zitzer, B. ; Fortin, P. ; Horan, D.
We report on the discovery of high-energy (HE; E > 0.1 GeV) and very high energy (VHE; E > 100 GeV) gamma-ray emission from the high-frequency-peaked BL Lac object RBS 0413. VERITAS, a ground-based gamma-ray observatory, detected VHE. rays from RBS 0413 with a statistical significance of 5.5 standard deviations (sigma) and a gamma-ray flux of (1.5 +/- 0.6(stat) +/- 0.7(syst)) x 10(-8) photons m(-2) s(-1) (similar to 1% of the Crab Nebula flux) above 250 GeV. The observed spectrum can be described by a power law with a photon index of 3.18 +/- 0.68(stat) +/- 0.30(syst). Contemporaneous observations with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope detected HE gamma rays from RBS 0413 with a (stat)istical significance of more than 9 sigma, a power-law photon index of 1.57 +/- 0.12(stat-0.12sys')(+0.11) and a gamma-ray flux between 300 MeV and 300 GeV of (1.64 +/- 0.43(stat-0.22sys)(+ 0.31)) x 10(-5) photons m(-2) s(-1). We present the results from Fermi-LAT and VERITAS, including a spectral energy distribution modeling of the gamma-ray, quasi-simultaneous X-ray (Swift-XRT), ultraviolet (Swift-UVOT), and R-band optical (MDM) data. We find that, if conditions close to equipartition are required, both the combined synchrotron self-Compton/external-Compton and the lepto-hadronic models are preferred over a pure synchrotron self-Compton model.
Archambault, S. ; Archer, A. ; Benbow, W. ; Bird, Ralph ; Bourbeau, E. ; Bouvier, A. ; Buchovecky, M. ; Bugaev, V. ; Cardenzana, J. V. ; Cerruti, M. ; Ciupik, L. ; Connolly, M. P. ; Cui, W. ; Daniel, M. K. ; Errando, M. ; Falcone, A. ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Fortson, L. ; Furniss, A. ; Gillanders, G. H. ; Griffin, S. ; Hanna, D. ; Hervet, O. ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Hutten, M. ; Johnson, C. A. ; Kaaret, P. ; Kar, P. ; Kertzman, M. ; Kieda, D. ; Krause, M. ; Lang, M. J. ; Lin, T. T. Y. ; Maier, G. ; McArthur, S. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Pohl, Martin ; Popkow, A. ; Pueschel, Elisa ; Quinn, J. ; Ragan, K. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Rulten, C. ; Sadeh, I. ; Sembroski, G. H. ; Shahinyan, K. ; Staszak, D. ; Telezhinsky, Igor O. ; Trepanier, S. ; Wakely, S. P. ; Weinstein, A. ; Wilcox, P. ; Williams, D. A. ; Zitzer, B.
Imaging atmospheric Cherenkov telescopes (IACTs) are equipped with sensitive photomultiplier tube (PMT) cameras. Exposure to high levels of background illumination degrades the efficiency of and potentially destroys these photo-detectors over time, so IACTs cannot be operated in the same configuration in the presence of bright moonlight as under dark skies. Since September 2012, observations have been carried out with the VERITAS IACTs under bright moonlight (defined as about three times the night-sky-background (NSB) of a dark extragalactic field, typically occurring when Moon illumination > 35%) in two observing modes, firstly by reducing the voltage applied to the PMTs and, secondly, with the addition of ultra-violet (UV) bandpass filters to the cameras. This has allowed observations at up to about 30 times previous NSB levels (around 80% Moon illumination), resulting in 30% more observing time between the two modes over the course of a year. These additional observations have already allowed for the detection of a flare from the 1ES 1727 + 502 and for an observing program targeting a measurement of the cosmic-ray positron fraction. We provide details of these new observing modes and their performance relative to the standard VERITAS observations. (C) 2017 Elsevier B.V. All rights reserved.