@article{ArchambaultArcherBenbowetal.2017,
  author    = {Archambault, S. and Archer, A. and Benbow, W. and Buchovecky, M. and Bugaev, V. and Cerruti, M. and Connolly, M. P. and Cui, W. and Falcone, A. and Alonso, M. Fernandez and Finley, J. P. and Fleischhack, H. and Fortson, L. and Furniss, A. and Griffin, S. and Hutten, M. and Hervet, O. and Holder, J. and Humensky, T. B. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kieda, D. and Krause, M. and Krennrich, F. and Lang, M. J. and Lin, T. T. Y. and Maier, G. and McArthur, S. and Moriarty, P. and Nieto, D. and Ong, R. A. and Otte, A. N. and Pohl, M. and Popkow, A. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Rovero, A. C. and Sadeh, I. and Shahinyan, K. and Staszak, D. and Telezhinsky, Igor O. and Tyler, J. and Wakely, S. P. and Weinstein, A. and Weisgarber, T. and Wilcox, P. and Wilhelm, Alina and Williams, D. A. and Zitzer, B.},
  title     = {Search for Magnetically Broadened Cascade Emission from Blazars with VERITAS},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {835},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.3847/1538-4357/835/2/288},
  pages     = {12},
  year      = {2017},
  abstract  = {We present a search for magnetically broadened gamma-ray emission around active galactic nuclei (AGNs), using VERITAS observations of seven hard-spectrum blazars. A cascade process occurs when multi-TeV gamma-rays from an AGN interact with extragalactic background light (EBL) photons to produce electron-positron pairs, which then interact with cosmic microwave background photons via inverse-Compton scattering to produce gamma-rays. Due to the deflection of the electron- positron pairs, a non-zero intergalactic magnetic field (IGMF) would potentially produce detectable effects on the angular distribution of the cascade emission. In particular, an angular broadening compared to the unscattered emission could occur. Through non-detection of angularly broadened emission from 1ES 1218 vertical bar 304, the source with the largest predicted cascade fraction, we exclude a range of IGMF strengths around 10(-14) G at the 95\% confidence level. The extent of the exclusion range varies with the assumptions made about the intrinsic spectrum of 1ES. 1218+304 and the EBL model used in the simulation of the cascade process. All of the sources are used to set limits on the flux due to extended emission.},
  language  = {en}
}
@article{ArchambaultArcherBenbowetal.2017,
  author    = {Archambault, S. and Archer, A. and Benbow, Wystan and Bird, Ralph and Bourbeau, E. and Buchovecky, M. and Buckley, J. H. and Bugaev, V. and Cerruti, M. and Connolly, M. P. and Cui, W. and Dwarkadas, Vikram V. and Errando, M. and Falcone, A. and Feng, Q. and Finley, J. P. and Fleischhack, H. and Fortson, L. and Furniss, A. and Griffin, S. and Huetten, M. and Hanna, D. and Holder, J. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kelley-Hoskins, N. and Kertzman, M. and Kieda, D. and Krause, M. and Kumar, S. and Lang, M. J. and Maier, G. and McArthur, S. and McCann, A. and Moriarty, P. and Mukherjee, R. and Nieto, D. and Ong, R. A. and Otte, A. N. and Park, Nahee and Pohl, Martin and Popkow, A. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Sadeh, I. and Santander, M. and Sembroski, G. H. and Shahinyan, K. and Slane, P. and Staszak, D. and Telezhinsky, Igor O. and Trepanier, S. and Tyler, J. and Wakely, S. P. and Weinstein, A. and Weisgarber, T. and Wilcox, P. and Wilhelm, Alina and Williams, D. A. and Zitzer, B.},
  title     = {Gamma-ray Observations of Tycho's Supernova Remnant with VERITAS and Fermi},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {836},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {1},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.3847/1538-4357/836/1/23},
  pages     = {8},
  year      = {2017},
  language  = {en}
}
@article{AbeysekaraArchambaultArcheretal.2017,
  author    = {Abeysekara, A. U. and Archambault, S. and Archer, A. and Benbow, Wystan and Bird, Ralph and Buchovecky, M. and Buckley, J. H. and Bugaev, V. and Byrum, K. and Cerruti, M. and Chen, X. and Ciupik, L. and Cui, W. and Dickinson, H. J. and Eisch, J. D. and Errando, M. and Falcone, A. and Feng, Q. and Finley, J. P. and Fleischhack, H. and Fortson, L. and Furniss, A. and Gillanders, G. H. and Griffin, S. and Grube, J. and Hutten, M. and Hakansson, N. and Hanna, D. and Holder, J. and Humensky, T. B. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kertzman, M. and Kieda, D. and Krause, M. and Krennrich, F. and Kumar, S. and Lang, M. J. and Maier, G. and McArthur, S. and McCann, A. and Meagher, K. and Moriarty, P. and Mukherjee, R. and Nguyen, T. and Nieto, D. and Ong, R. A. and Otte, A. N. and Park, N. and Pelassa, V. and Pohl, Martin and Popkow, A. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Rulten, C. and Santander, M. and Sembroski, G. H. and Shahinyan, K. and Staszak, D. and Telezhinsky, Igor O. and Tucci, J. V. and Tyler, J. and Wakely, S. P. and Weiner, O. M. and Weinstein, A. and Wilhelm, Alina and Williams, D. A. and Fegan, S. and Giebels, B. and Horan, D. and Berdyugin, A. and Kuan, J. and Lindfors, E. and Nilsson, K. and Oksanen, A. and Prokoph, H. and Reinthal, R. and Takalo, L. and Zefi, F.},
  title     = {A Luminous and Isolated Gamma-Ray Flare from the Blazar B2 1215+30},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {836},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  organization    = {VERITAS Collaboration;Fermi-LAT Collaboration},
  issn      = {0004-637X},
  doi       = {10.3847/1538-4357/836/2/205},
  pages     = {6},
  year      = {2017},
  abstract  = {B2 1215+30 is a BL-Lac-type blazar that was first detected at TeV energies by the MAGIC atmospheric Cherenkov telescopes and subsequently confirmed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory with data collected between 2009 and 2012. In 2014 February 08, VERITAS detected a large-amplitude flare from B2. 1215+30 during routine monitoring observations of the blazar 1ES. 1218+304, located in the same field of view. The TeV flux reached 2.4 times the Crab Nebula flux with a variability timescale of <3.6 hr. Multiwavelength observations with Fermi-LAT, Swift, and the Tuorla Observatory revealed a correlated high GeV flux state and no significant optical counterpart to the flare, with a spectral energy distribution where the gamma-ray luminosity exceeds the synchrotron luminosity. When interpreted in the framework of a onezone leptonic model, the observed emission implies a high degree of beaming, with Doppler factor delta > 10, and an electron population with spectral index p < 2.3.},
  language  = {en}
}
@article{ArchambaultArcherBenbowetal.2017,
  author    = {Archambault, S. and Archer, A. and Benbow, W. and Bird, Ralph and Bourbeau, E. and Bouvier, A. and Buchovecky, M. and Bugaev, V. and Cardenzana, J. V. and Cerruti, M. and Ciupik, L. and Connolly, M. P. and Cui, W. and Daniel, M. K. and Errando, M. and Falcone, A. and Feng, Q. and Finley, J. P. and Fleischhack, H. and Fortson, L. and Furniss, A. and Gillanders, G. H. and Griffin, S. and Hanna, D. and Hervet, O. and Holder, J. and Hughes, G. and Humensky, T. B. and Hutten, M. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kertzman, M. and Kieda, D. and Krause, M. and Lang, M. J. and Lin, T. T. Y. and Maier, G. and McArthur, S. and Moriarty, P. and Mukherjee, R. and Nieto, D. and Ong, R. A. and Otte, A. N. and Park, N. and Pohl, Martin and Popkow, A. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Rulten, C. and Sadeh, I. and Sembroski, G. H. and Shahinyan, K. and Staszak, D. and Telezhinsky, Igor O. and Trepanier, S. and Wakely, S. P. and Weinstein, A. and Wilcox, P. and Williams, D. A. and Zitzer, B.},
  title     = {Gamma-ray observations under bright moonlight with VERITAS},
  series = {Astroparticle physics},
  volume    = {91},
  journal   = {Astroparticle physics},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0927-6505},
  doi       = {10.1016/j.astropartphys.2017.03.001},
  pages     = {34 -- 43},
  year      = {2017},
  abstract  = {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.},
  language  = {en}
}
@article{AceroAloisioAmansetal.2017,
  author    = {Acero, F. and Aloisio, R. and Amans, J. and Amato, Elena and Antonelli, L. A. and Aramo, C. and Armstrong, T. and Arqueros, F. and Asano, Katsuaki and Ashley, M. and Backes, M. and Balazs, C. and Balzer, A. and Bamba, Aya and Barkov, Maxim and Barrio, J. A. and Benbow, Wystan and Bernloehr, K. and Beshley, V. and Bigongiari, C. and Biland, A. and Bilinsky, A. and Bissaldi, Elisabetta and Biteau, J. and Blanch, O. and Blasi, P. and Blazek, J. and Boisson, C. and Bonanno, G. and Bonardi, A. and Bonavolonta, C. and Bonnoli, G. and Braiding, C. and Brau-Nogue, S. and Bregeon, J. and Brown, A. M. and Bugaev, V. and Bulgarelli, A. and Bulik, T. and Burton, Michael and Burtovoi, A. and Busetto, G. and Bottcher, M. and Cameron, R. and Capalbi, M. and Caproni, Anderson and Caraveo, P. and Carosi, R. and Cascone, E. and Cerruti, M. and Chaty, Sylvain and Chen, A. and Chen, X. and Chernyakova, M. and Chikawa, M. and Chudoba, J. and Cohen-Tanugi, J. and Colafrancesco, S. and Conforti, V. and Contreras, J. L. and Costa, A. and Cotter, G. and Covino, Stefano and Covone, G. and Cumani, P. and Cusumano, G. and Daniel, M. and Dazzi, F. and De Angelis, A. and De Cesare, G. and De Franco, A. and De Frondat, F. and Dal Pino, E. M. de Gouveia and De Lisio, C. and Lopez, R. de los Reyes and De Lotto, B. and de Naurois, M. and De Palma, F. and Del Santo, M. and Delgado, C. and della Volpe, D. and Di Girolamo, T. and Di Giulio, C. and Di Pierro, F. and Di Venere, L. and Doro, M. and Dournaux, J. and Dumas, D. and Dwarkadas, Vikram V. and Diaz, C. and Ebr, J. and Egberts, Kathrin and Einecke, S. and Elsaesser, D. and Eschbach, S. and Falceta-Goncalves, D. and Fasola, G. and Fedorova, E. and Fernandez-Barral, A. and Ferrand, Gilles and Fesquet, M. and Fiandrini, E. and Fiasson, A. and Filipovic, Miroslav D. and Fioretti, V. and Font, L. and Fontaine, Gilles and Franco, F. J. and Freixas Coromina, L. and Fujita, Yutaka and Fukui, Y. and Funk, S. and Forster, A. and Gadola, A. and Lopez, R. Garcia and Garczarczyk, M. and Giglietto, N. and Giordano, F. and Giuliani, A. and Glicenstein, J. and Gnatyk, R. and Goldoni, P. and Grabarczyk, T. and Graciani, R. and Graham, J. and Grandi, P. and Granot, Jonathan and Green, A. J. and Griffiths, S. and Gunji, S. and Hakobyan, H. and Hara, S. and Hassan, T. and Hayashida, M. and Heller, M. and Helo, J. C. and Hinton, J. and Hnatyk, B. and Huet, J. and Huetten, M. and Humensky, T. B. and Hussein, M. and Horandel, J. and Ikeno, Y. and Inada, T. and Inome, Y. and Inoue, S. and Inoue, T. and Inoue, Y. and Ioka, K. and Iori, Maurizio and Jacquemier, J. and Janecek, P. and Jankowsky, D. and Jung, I. and Kaaret, P. and Katagiri, H. and Kimeswenger, S. and Kimura, Shigeo S. and Knodlseder, J. and Koch, B. and Kocot, J. and Kohri, K. and Komin, N. and Konno, Y. and Kosack, K. and Koyama, S. and Kraus, Michaela and Kubo, Hidetoshi and Mezek, G. Kukec and Kushida, J. and La Palombara, N. and Lalik, K. and Lamanna, G. and Landt, H. and Lapington, J. and Laporte, P. and Lee, S. and Lees, J. and Lefaucheur, J. and Lenain, J. -P. and Leto, Giuseppe and Lindfors, E. and Lohse, T. and Lombardi, S. and Longo, F. and Lopez, M. and Lucarelli, F. and Luque-Escamilla, Pedro Luis and Lopez-Coto, R. and Maccarone, M. C. and Maier, G. and Malaguti, G. and Mandat, D. and Maneva, G. and Mangano, S. and Marcowith, Alexandre and Marti, J. and Martinez, M. and Martinez, G. and Masuda, S. and Maurin, G. and Maxted, N. and Melioli, Claudio and Mineo, T. and Mirabal, N. and Mizuno, T. and Moderski, R. and Mohammed, M. and Montaruli, T. and Moralejo, A. and Mori, K. and Morlino, G. and Morselli, A. and Moulin, Emmanuel and Mukherjee, R. and Mundell, C. and Muraishi, H. and Murase, Kohta and Nagataki, Shigehiro and Nagayoshi, T. and Naito, T. and Nakajima, D. and Nakamori, T. and Nemmen, R. and Niemiec, Jacek and Nieto, D. and Nievas-Rosillo, M. and Nikolajuk, M. and Nishijima, K. and Noda, K. and Nogues, L. and Nosek, D. and Novosyadlyj, B. and Nozaki, S. and Ohira, Yutaka and Ohishi, M. and Ohm, S. and Okumura, A. and Ong, R. A. and Orito, R. and Orlati, A. and Ostrowski, M. and Oya, I. and Padovani, Marco and Palacio, J. and Palatka, M. and Paredes, Josep M. and Pavy, S. and Persic, M. and Petrucci, P. and Petruk, Oleh and Pisarski, A. and Pohl, Martin and Porcelli, A. and Prandini, E. and Prast, J. and Principe, G. and Prouza, M. and Pueschel, Elisa and Puelhofer, G. and Quirrenbach, A. and Rameez, M. and Reimer, O. and Renaud, M. and Ribo, M. and Rico, J. and Rizi, V. and Rodriguez, J. and Fernandez, G. Rodriguez and Rodriguez Vazquez, J. J. and Romano, Patrizia and Romeo, G. and Rosado, J. and Rousselle, J. and Rowell, G. and Rudak, B. and Sadeh, I. and Safi-Harb, S. and Saito, T. and Sakaki, N. and Sanchez, D. and Sangiorgi, P. and Sano, H. and Santander, M. and Sarkar, S. and Sawada, M. and Schioppa, E. J. and Schoorlemmer, H. and Schovanek, P. and Schussler, F. and Sergijenko, O. and Servillat, M. and Shalchi, A. and Shellard, R. C. and Siejkowski, H. and Sillanpaa, A. and Simone, D. and Sliusar, V. and Sol, H. and Stanic, S. and Starling, R. and Stawarz, L. and Stefanik, S. and Stephan, M. and Stolarczyk, T. and Szanecki, M. and Szepieniec, T. and Tagliaferri, G. and Tajima, H. and Takahashi, M. and Takeda, J. and Tanaka, M. and Tanaka, S. and Tejedor, L. A. and Telezhinsky, Igor O. and Temnikov, P. and Terada, Y. and Tescaro, D. and Teshima, M. and Testa, V. and Thoudam, S. and Tokanai, F. and Torres, D. F. and Torresi, E. and Tosti, G. and Townsley, C. and Travnicek, P. and Trichard, C. and Trifoglio, M. and Tsujimoto, S. and Vagelli, V. and Vallania, P. and Valore, L. and van Driel, W. and van Eldik, C. and Vandenbroucke, Justin and Vassiliev, V. and Vecchi, M. and Vercellone, Stefano and Vergani, S. and Vigorito, C. and Vorobiov, S. and Vrastil, M. and Vazquez Acosta, M. L. and Wagner, S. J. and Wagner, R. and Wakely, S. P. and Walter, R. and Ward, J. E. and Watson, J. J. and Weinstein, A. and White, M. and White, R. and Wierzcholska, A. and Wilcox, P. and Williams, D. A. and Wischnewski, R. and Wojcik, P. and Yamamoto, T. and Yamamoto, H. and Yamazaki, Ryo and Yanagita, S. and Yang, L. and Yoshida, T. and Yoshida, M. and Yoshiike, S. and Yoshikoshi, T. and Zacharias, M. and Zampieri, L. and Zanin, R. and Zavrtanik, M. and Zavrtanik, D. and Zdziarski, A. and Zech, Alraune and Zechlin, Hannes and Zhdanov, V. and Ziegler, A. and Zorn, J.},
  title     = {Prospects for Cherenkov Telescope Array Observations of the Young Supernova Remnant RX J1713.7-3946},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {840},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.3847/1538-4357/aa6d67},
  pages     = {14},
  year      = {2017},
  abstract  = {We perform simulations for future Cherenkov Telescope Array (CTA) observations of RX J1713.7-3946, a young supernova remnant (SNR) and one of the brightest sources ever discovered in very high energy (VHE) gamma rays. Special attention is paid to exploring possible spatial (anti) correlations of gamma rays with emission at other wavelengths, in particular X-rays and CO/H I emission. We present a series of simulated images of RX J1713.7-3946 for CTA based on a set of observationally motivated models for the gamma-ray emission. In these models, VHE gamma rays produced by high-energy electrons are assumed to trace the nonthermal X-ray emission observed by XMM-Newton, whereas those originating from relativistic protons delineate the local gas distributions. The local atomic and molecular gas distributions are deduced by the NANTEN team from CO and H I observations. Our primary goal is to show how one can distinguish the emission mechanism(s) of the gamma rays (i.e., hadronic versus leptonic, or a mixture of the two) through information provided by their spatial distribution, spectra, and time variation. This work is the first attempt to quantitatively evaluate the capabilities of CTA to achieve various proposed scientific goals by observing this important cosmic particle accelerator.},
  language  = {en}
}
@article{AhnenAnsoldiAntonellietal.2017,
  author    = {Ahnen, M. L. and Ansoldi, S. and Antonelli, L. A. and Antoranz, P. and Babic, A. and Banerjee, B. and Bangale, P. and de Almeida, U. Barres and Barrio, J. A. and Gonzalez, J. Becerra and Bednarek, W. and Bernardini, E. and Berti, A. and Biasuzzi, B. and Biland, A. and Blanch, O. and Bonnefoy, S. and Bonnoli, G. and Borracci, F. and Bretz, T. and Buson, S. and Carosi, A. and Chatterjee, A. and Clavero, R. and Colin, P. and Colombo, E. and Contreras, J. L. and Cortina, J. and Covino, S. and Da Vela, P. and Dazzi, F. and De Angelis, A. and De Lotto, B. and Wilhelmi, E. de Ona and Di Pierro, F. and Doert, M. and Dominguez, A. and Prester, D. Dominis and Dorner, D. and Doro, M. and Einecke, S. and Glawion, D. Eisenacher and Elsaesser, D. and Engelkemeier, M. and Ramazani, V. Fallah and Fernandez-Barral, A. and Fidalgo, D. and Fonseca, M. V. and Font, L. and Frantzen, K. and Fruck, C. and Galindo, D. and Lopez, R. J. Garcia and Garczarczyk, M. and Terrats, D. Garrido and Gaug, M. and Giammaria, P. and Godinovic, N. and Gonzalez Munoz, A. and Gora, D. and Guberman, D. and Hadasch, D. and Hahn, A. and Hanabata, Y. and Hayashida, M. and Herrera, J. and Hose, J. and Hrupec, D. and Hughes, G. and Idec, W. and Kodani, K. and Konno, Y. and Kubo, H. and Kushida, J. and La Barbera, A. and Lelas, D. and Lindfors, E. and Lombardi, S. and Longo, F. and Lopez, M. and Lopez-Coto, R. and Majumdar, P. and Makariev, M. and Mallot, K. and Maneva, G. and Manganaro, M. and Mannheim, K. and Maraschi, L. and Marcote, B. and Mariotti, M. and Martinez, M. and Mazin, D. and Menzel, U. and Miranda, J. M. and Mirzoyan, R. and Moralejo, A. and Moretti, E. and Nakajima, D. and Neustroev, V. and Niedzwiecki, A. and Rosillo, M. Nievas and Nilsson, K. and Nishijima, K. and Noda, K. and Nogues, L. and Overkemping, A. and Paiano, S. and Palacio, J. and Palatiello, M. and Paneque, D. and Paoletti, R. and Paredes, J. M. and Paredes-Fortuny, X. and Pedaletti, G. and Peresano, M. and Perri, L. and Persic, M. and Poutanen, J. and Moroni, P. G. Prada and Prandini, E. and Puljak, I. and Reichardt, I. and Rhode, W. and Ribo, M. and Rico, J. and Rodriguez Garcia, J. and Saito, T. and Satalecka, K. and Schroder, S. and Schultz, C. and Schweizer, T. and Shore, S. N. and Sillanpaa, A. and Sitarek, J. and Snidaric, I. and Sobczynska, D. and Stamerra, A. and Steinbring, T. and Strzys, M. and Suric, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzic, T. and Tescaro, D. and Teshima, M. and Thaele, J. and Torres, D. F. and Toyama, T. and Treves, A. and Vanzo, G. and Verguilov, V. and Vovk, I. and Ward, J. E. and Will, M. and Wu, M. H. and Zanin, R. and Abeysekara, A. U. and Archambault, S. and Archer, A. and Benbow, W. and Bird, R. and Buchovecky, M. and Buckley, J. H. and Bugaev, V. and Connolly, M. P. and Cui, W. and Dickinson, H. J. and Falcone, A. and Feng, Q. and Finley, J. P. and Fleischhack, H. and Flinders, A. and Fortson, L. and Gillanders, G. H. and Griffin, S. and Grube, J. and Huetten, M. and Hanna, D. and Holder, J. and Humensky, T. B. and Kaaret, P. and Kar, P. and Kelley-Hoskins, N. and Kertzman, M. and Kieda, D. and Krause, M. and Krennrich, F. and Lang, M. J. and Maier, G. and McCann, A. and Moriarty, P. and Mukherjee, R. and Nieto, D. and Ong, R. A. and Otte, N. and Park, N. and Perkins, J. and Pichel, A. and Pohl, M. and Popkow, A. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Rovero, A. C. and Rulten, C. and Sadeh, I. and Santander, M. and Sembroski, G. H. and Shahinyan, K. and Telezhinsky, Igor O. and Tucci, J. V. and Tyler, J. and Wakely, S. P. and Weinstein, A. and Wilcox, P. and Wilhelm, Alina and Williams, D. A. and Zitzer, B. and Razzaque, S. and Villata, M. and Raiteri, C. M. and Aller, H. D. and Aller, M. F. and Larionov, V. M. and Arkharov, A. A. and Blinov, D. A. and Efimova, N. V. and Grishina, T. S. and Hagen-Thorn, V. A. and Kopatskaya, E. N. and Larionova, L. V. and Larionova, E. G. and Morozova, D. A. and Troitsky, I. S. and Ligustri, R. and Calcidese, P. and Berdyugin, A. and Kurtanidze, O. M. and Nikolashvili, M. G. and Kimeridze, G. N. and Sigua, L. A. and Kurtanidze, S. O. and Chigladze, R. A. and Chen, W. P. and Koptelova, E. and Sakamoto, T. and Sadun, A. C. and Moody, J. W. and Pace, C. and Pearson, R. and Yatsu, Y. and Mori, Y. and Carraminyana, A. and Carrasco, L. and de la Fuente, E. and Norris, J. P. and Smith, P. S. and Wehrle, A. and Gurwell, M. A. and Zook, A. and Pagani, C. and Perri, M. and Capalbi, M. and Cesarini, A. and Krimm, H. A. and Kovalev, Y. Y. and Kovalev, Yu. A. and Ros, E. and Pushkarev, A. B. and Lister, M. L. and Sokolovsky, K. V. and Kadler, M. and Piner, G. and Lahteenmaki, A. and Tornikoski, M. and Angelakis, E. and Krichbaum, T. P. and Nestoras, I. and Fuhrmann, L. and Zensus, J. A. and Cassaro, P. and Orlati, A. and Maccaferri, G. and Leto, P. and Giroletti, M. and Richards, J. L. and Max-Moerbeck, W. and Readhead, A. C. S.},
  title     = {Multiband variability studies and novel broadband SED modeling of Mrk 501 in 2009},
  series = {Astronomy and astrophysics : an international weekly journal},
  volume    = {603},
  journal   = {Astronomy and astrophysics : an international weekly journal},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  organization    = {MAGIC Collaboration;VERITAS Collaboration},
  issn      = {1432-0746},
  doi       = {10.1051/0004-6361/201629540},
  pages     = {30},
  year      = {2017},
  abstract  = {Aims. We present an extensive study of the BL Lac object Mrk 501 based on a data set collected during the multi-instrument campaign spanning from 2009 March 15 to 2009 August 1, which includes, among other instruments, MAGIC, VERITAS, Whipple 10 m, and Fermi-LAT to cover the gamma-ray range from 0.1 GeV to 20 TeV; RXTE and Swift to cover wavelengths from UV to hard X-rays; and GASP-WEBT, which provides coverage of radio and optical wavelengths. Optical polarization measurements were provided for a fraction of the campaign by the Steward and St. Petersburg observatories. We evaluate the variability of the source and interband correlations, the gamma-ray flaring activity occurring in May 2009, and interpret the results within two synchrotron self-Compton (SSC) scenarios. Methods. The multiband variability observed during the full campaign is addressed in terms of the fractional variability, and the possible correlations are studied by calculating the discrete correlation function for each pair of energy bands where the significance was evaluated with dedicated Monte Carlo simulations. The space of SSC model parameters is probed following a dedicated grid-scan strategy, allowing for a wide range of models to be tested and offering a study of the degeneracy of model-to-data agreement in the individual model parameters, hence providing a less biased interpretation than the "single-curve SSC model adjustment" typically reported in the literature. Results. We find an increase in the fractional variability with energy, while no significant interband correlations of flux changes are found on the basis of the acquired data set. The SSC model grid-scan shows that the flaring activity around May 22 cannot be modeled adequately with a one-zone SSC scenario (using an electron energy distribution with two breaks), while it can be suitably described within a two (independent) zone SSC scenario. Here, one zone is responsible for the quiescent emission from the averaged 4.5-month observing period, while the other one, which is spatially separated from the first, dominates the flaring emission occurring at X-rays and very-high-energy (> 100 GeV, VHE) gamma-rays. The flaring activity from May 1, which coincides with a rotation of the electric vector polarization angle (EVPA), cannot be satisfactorily reproduced by either a one-zone or a two-independent-zone SSC model, yet this is partially affected by the lack of strictly simultaneous observations and the presence of large flux changes on sub-hour timescales (detected at VHE gamma rays). Conclusions. The higher variability in the VHE emission and lack of correlation with the X-ray emission indicate that, at least during the 4.5-month observing campaign in 2009, the highest energy (and most variable) electrons that are responsible for the VHE gamma rays do not make a dominant contribution to the similar to 1 keV emission. Alternatively, there could be a very variable component contributing to the VHE gamma-ray emission in addition to that coming from the SSC scenario. The studies with our dedicated SSC grid-scan show that there is some degeneracy in both the one-zone and the two-zone SSC scenarios probed, with several combinations of model parameters yielding a similar model-to-data agreement, and some parameters better constrained than others. The observed gamma-ray flaring activity, with the EVPA rotation coincident with the first gamma-ray flare, resembles those reported previously for low frequency peaked blazars, hence suggesting that there are many similarities in the flaring mechanisms of blazars with different jet properties.},
  language  = {en}
}
@article{ArcherBenbowBirdetal.2018,
  author    = {Archer, A. and Benbow, W. and Bird, R. and Brose, Robert and Buchovecky, M. and Bugaev, V. and Connolly, M. P. and Cui, W. and Daniel, M. K. and Falcone, A. and Feng, Q. and Finley, J. P. and Fleischhack, H. and Fortson, L. and Furniss, A. and Hanna, D. and Hervet, O. and Holder, J. and Hughes, G. and Humensky, T. B. and Hutten, M. and Johnson, C. A. and Kaaret, P. and Kelley-Hoskins, N. and Kieda, D. and Krause, M. and Krennrich, F. and Kumar, S. and Lang, M. J. and Maier, G. and McArthur, S. and Moriarty, P. and Mukherjee, R. and Nieto, D. and Ong, R. A. and Otte, A. N. and Park, N. and Petrashyk, A. and Pohl, Martin and Popkow, A. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Rulten, C. and Sadeh, I. and Tyler, J. and Wakely, S. P. and Weiner, O. M. and Wilcox, P. and Wilhelm, Alina and Williams, D. A. and Wissel, S. A. and Zitzer, B.},
  title     = {Measurement of the iron spectrum in cosmic rays by VERITAS},
  series = {Physical review : D, Particles, fields, gravitation, and cosmology},
  volume    = {98},
  journal   = {Physical review : D, Particles, fields, gravitation, and cosmology},
  number    = {2},
  publisher = {American Physical Society},
  address   = {College Park},
  organization    = {VERITAS Collaboration},
  issn      = {2470-0010},
  doi       = {10.1103/PhysRevD.98.022009},
  pages     = {15},
  year      = {2018},
  abstract  = {We present a new measurement of the energy spectrum of iron nuclei in cosmic rays from 20 TeV to 500 TeV; The measurement makes use of a template-based analysis method, which, for the first time, is applied to the energy reconstruction of iron-induced air showers recorded by the VERITAS array of imaging atmospheric Cherenkov telescopes. The event selection makes use of the direct Cherenkov light which is emitted by charged particles before the first interaction, as well as other parameters related to the shape of the recorded air shower images. The measured spectrum is well described by a power law dF/dE = f(0) center dot (E/E-0)(-gamma) over the full energy range, with gamma = 2.82 +/- 0.30(stat)(-0.27)(+0.24)(syst) and f(0) = (4.82 +/- 0.98(stat)(-2.70)(+2.12)(syst)) x 10(-7) m(-2) s(-1) TeV-1 sr(-1) at E-0 = 50 TeV, with no indication of a cutoff or spectral break. The measured differential flux is compatible with previous results, with improved statistical uncertainty at the highest energies.},
  language  = {en}
}
@article{ArcherBenbowBirdetal.2018,
  author    = {Archer, A. and Benbow, W. and Bird, R. and Brose, Robert and Buchovecky, M. and Buckley, J. H. and Bugaev, V. and Connolly, M. P. and Cui, W. and Daniel, M. K. and Feng, Q. and Finley, J. P. and Fortson, L. and Furniss, A. and Gillanders, G. and Huetten, M. and Hanna, D. and Hervet, O. and Holder, J. and Hughes, G. and Humensky, T. B. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kelley-Hoskins, N. and Kertzman, M. and Kieda, D. and Krause, M. and Krennrich, F. and Kumar, S. and Lang, M. J. and Lin, T. T. Y. and Maier, G. and McArthur, S. and Moriarty, P. and Mukherjee, R. and Ong, R. A. and Otte, A. N. and Petrashyk, A. and Pohl, M. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Rulten, C. and Sadeh, I. and Santander, M. and Sembroski, G. H. and Staszak, D. and Sushch, I. and Wakely, S. P. and Wells, R. M. and Wilcox, P. and Wilhelm, Alina and Williams, D. A. and Williamson, T. J. and Zitzer, B.},
  title     = {Measurement of cosmic-ray electrons at TeV energies by VERITAS},
  series = {Physical review : D, Particles, fields, gravitation, and cosmology},
  volume    = {98},
  journal   = {Physical review : D, Particles, fields, gravitation, and cosmology},
  number    = {6},
  publisher = {American Physical Society},
  address   = {College Park},
  organization    = {VERITAS Collaboration},
  issn      = {2470-0010},
  doi       = {10.1103/PhysRevD.98.062004},
  pages     = {7},
  year      = {2018},
  abstract  = {Cosmic-ray electrons and positrons (CREs) at GeV-TeV energies are a unique probe of our local Galactic neighborhood. CREs lose energy rapidly via synchrotron radiation and inverse-Compton scattering processes while propagating within the Galaxy, and these losses limit their propagation distance. For electrons with TeV energies, the limit is on the order of a kiloparsec. Within that distance, there are only a few known astrophysical objects capable of accelerating electrons to such high energies. It is also possible that the CREs are the products of the annihilation or decay of heavy dark matter (DM) particles. VERITAS, an array of imaging air Cherenkov telescopes in southern Arizona, is primarily utilized for gamma-ray astronomy but also simultaneously collects CREs during all observations. We describe our methods of identifying CREs in VERITAS data and present an energy spectrum, extending from 300 GeV to 5 TeV, obtained from approximately 300 hours of observations. A single power-law fit is ruled out in VERITAS data. We find that the spectrum of CREs is consistent with a broken power law, with a break energy at 710 +/- 40(stat) +/- 140(syst) GeV.},
  language  = {en}
}
@article{AhnenAnsoldiAntonellietal.2018,
  author    = {Ahnen, M. L. and Ansoldi, S. and Antonelli, L. A. and Arcaro, C. and Babic, A. and Banerjee, B. and Bangale, P. and Barres de Almeida, U. and Barrio, J. A. and Gonzalez, J. Becerra and Bednarek, W. and Bernardini, E. and Berti, A. and Bhattacharyya, W. and Blanch, O. and Bonnoli, G. and Carosi, R. and Carosi, A. and Chatterjee, A. and Colak, S. M. and Colin, P. and Colombo, E. and Contreras, J. L. and Cortina, J. and Covino, S. and Cumani, P. and Da Vela, P. and Dazzi, F. and De Angelis, A. and De Lotto, B. and Delfino, M. and Delgado, Jose Miguel Martins and Di Pierro, F. and Doert, M. and Dominguez, A. and Prester, D. Dominis and Doro, M. and Glawion, D. Eisenacher and Engelkemeier, M. and Ramazani, V. Fallah and Fernandez-Barral, A. and Fidalgo, D. and Fonseca, M. V. and Font, L. and Fruck, C. and Galindo, D. and Lopez, R. J. Garcia and Garczarczyk, M. and Gaug, M. and Giammaria, P. and Godinovic, N. and Gora, D. and Guberman, D. and Hadasch, D. and Hahn, A. and Hassan, T. and Hayashida, M. and Herrera, J. and Hose, J. and Hrupec, D. and Ishio, K. and Konno, Y. and Kubo, H. and Kushida, J. and Kuvezdic, D. and Lelas, D. and Lindfors, E. and Lombardi, S. and Longo, F. and Lopez, M. and Maggio, C. and Majumdar, P. and Makariev, M. and Maneva, G. and Manganaro, M. and Maraschi, L. and Mariotti, M. and Martinez, M. and Mazin, D. and Menzel, U. and Minev, M. and Miranda, J. M. and Mirzoyan, R. and Moralejo, A. and Moreno, V. and Moretti, E. and Nagayoshi, T. and Neustroev, V. and Niedzwiecki, A. and Nievas Rosillo, M. and Nigro, C. and Nilsson, K. and Ninci, D. and Nishijima, K. and Noda, K. and Nogues, L. and Paiano, S. and Palacio, J. and Paneque, D. and Paoletti, R. and Paredes, J. M. and Pedaletti, G. and Peresano, M. and Perri, L. and Persic, M. and Moroni, P. G. Prada and Prandini, E. and Puljak, I. and Garcia, J. R. and Reichardt, I. and Ribo, M. and Rico, J. and Righi, C. and Rugliancich, A. and Saito, T. and Satalecka, K. and Schroeder, S. and Schweizer, T. and Shore, S. N. and Sitarek, J. and Snidaric, I. and Sobczynska, D. and Stamerra, A. and Strzys, M. and Suric, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzic, T. and Teshima, M. and Torres-Alba, N. and Treves, A. and Tsujimoto, S. and Vanzo, G. and Vazquez Acosta, M. and Vovk, I. and Ward, J. E. and Will, M. and Zaric, D. and Arbet-Engels, A. and Baack, D. and Balbo, M. and Biland, A. and Blank, M. and Bretz, T. and Bruegge, K. and Bulinski, M. and Buss, J. and Dmytriiev, A. and Dorner, D. and Einecke, S. and Elsaesser, D. and Herbst, T. and Hildebrand, D. and Kortmann, L. and Linhoff, L. and Mahlke, M. and Mannheim, K. and Mueller, S. A. and Neise, D. and Neronov, A. and Noethe, M. and Oberkirch, J. and Paravac, A. and Rhode, W. and Schleicher, B. and Schulz, F. and Sedlaczek, K. and Shukla, A. and Sliusar, V. and Walter, R. and Archer, A. and Benbow, W. and Bird, R. and Brose, Robert and Buckley, J. H. and Bugaev, V. and Christiansen, J. L. and Cui, W. and Daniel, M. K. and Falcone, A. and Feng, Q. and Finley, J. P. and Gillanders, G. H. and Gueta, O. and Hanna, D. and Hervet, O. and Holder, J. and Hughes, G. and Huetten, M. and Humensky, T. B. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kelley-Hoskins, N. and Kertzman, M. and Kieda, D. and Krause, M. and Krennrich, F. and Kumar, S. and Lang, M. J. and Lin, T. T. Y. and Maier, G. and McArthur, S. and Moriarty, P. and Mukherjee, R. and Ong, R. A. and Otte, A. N. and Park, N. and Petrashyk, A. and Pichel, A. and Pohl, Martin and Quinn, J. and Ragan, K. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Rovero, A. C. and Rulten, C. and Sadeh, I. and Santander, M. and Sembroski, G. H. and Shahinyan, K. and Sushch, Iurii and Tyler, J. and Wakely, S. P. and Weinstein, A. and Wells, R. M. and Wilcox, P. and Wilhel, A. and Williams, D. A. and Williamson, T. J. and Zitzer, B. and Perri, M. and Verrecchia, F. and Leto, C. and Villata, M. and Raiteri, C. M. and Jorstad, S. G. and Larionov, V. M. and Blinov, D. A. and Grishina, T. S. and Kopatskaya, E. N. and Larionova, E. G. and Nikiforova, A. A. and Morozova, D. A. and Troitskaya, Yu. V. and Troitsky, I. S. and Kurtanidze, O. M. and Nikolashvili, M. G. and Kurtanidze, S. O. and Kimeridze, G. N. and Chigladze, R. A. and Strigachev, A. and Sadun, A. C.},
  title     = {Extreme HBL behavior of Markarian 501 during 2012},
  series = {Astronomy and astrophysics : an international weekly journal / European Southern Observatory (ESO)},
  volume    = {620},
  journal   = {Astronomy and astrophysics : an international weekly journal / European Southern Observatory (ESO)},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  organization    = {MAGIC Collaboration FACT Collaboration VERITAS Collaboration},
  issn      = {1432-0746},
  doi       = {10.1051/0004-6361/201833704},
  pages     = {23},
  year      = {2018},
  abstract  = {Aims. We aim to characterize the multiwavelength emission from Markarian 501 (Mrk 501), quantify the energy-dependent variability, study the potential multiband correlations, and describe the temporal evolution of the broadband emission within leptonic theoretical scenarios. Methods. We organized a multiwavelength campaign to take place between March and July of 2012. Excellent temporal coverage was obtained with more than 25 instruments, including the MAGIC, FACT and VERITAS Cherenkov telescopes, the instruments on board the Swift and Fermi spacecraft, and the telescopes operated by the GASP-WEBT collaboration. Results. Mrk 501 showed a very high energy (VHE) gamma-ray flux above 0.2 TeV of similar to 0.5 times the Crab Nebula flux (CU) for most of the campaign. The highest activity occurred on 2012 June 9, when the VHE flux was similar to 3 CU, and the peak of the high-energy spectral component was found to be at similar to 2 TeV. Both the X-ray and VHE gamma-ray spectral slopes were measured to be extremely hard, with spectral indices <2 during most of the observing campaign, regardless of the X-ray and VHE flux. This study reports the hardest Mrk 501 VHE spectra measured to date. The fractional variability was found to increase with energy, with the highest variability occurring at VHE. Using the complete data set, we found correlation between the X-ray and VHE bands; however, if the June 9 flare is excluded, the correlation disappears (significance <3 sigma) despite the existence of substantial variability in the X-ray and VHE bands throughout the campaign. Conclusions. The unprecedentedly hard X-ray and VHE spectra measured imply that their low- and high-energy components peaked above 5 keV and 0.5 TeV, respectively, during a large fraction of the observing campaign, and hence that Mrk 501 behaved like an extreme high-frequency-peaked blazar (EHBL) throughout the 2012 observing season. This suggests that being an EHBL may not be a permanent characteristic of a blazar, but rather a state which may change over time. The data set acquired shows that the broadband spectral energy distribution (SED) of Mrk 501, and its transient evolution, is very complex, requiring, within the framework of synchrotron self-Compton (SSC) models, various emission regions for a satisfactory description. Nevertheless the one-zone SSC scenario can successfully describe the segments of the SED where most energy is emitted, with a significant correlation between the electron energy density and the VHE gamma-ray activity, suggesting that most of the variability may be explained by the injection of high-energy electrons. The one-zone SSC scenario used reproduces the behavior seen between the measured X-ray and VHE gamma-ray fluxes, and predicts that the correlation becomes stronger with increasing energy of the X-rays.},
  language  = {en}
}
@article{AllenArchambaultArcheretal.2017,
  author    = {Allen, C. and Archambault, S. and Archer, A. and Benbow, W. and Bird, R. and Bourbeau, E. and Brose, Robert and Buchovecky, M. and Buckley, J. H. and Bugaev, V. and Cardenzana, J. V. and Cerruti, M. and Chen, Xuhui and Christiansen, J. L. and Connolly, M. P. and Cui, W. and Daniel, M. K. and Eisch, J. D. and Falcone, Abe and Feng, Q. and Fernandez-Alonso, M. and Finley, J. P. and Fleischhack, H. and Flinders, A. and Fortson, L. and Furniss, A. and Gillanders, G. H. and Griffin, S. and Grube, J. and Huetten, M. and Hakansson, N. and Hanna, D. and Hervet, O. and Holder, J. and Hughes, G. and Humensky, T. B. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kelley-Hoskins, N. and Kertzman, M. and Kieda, D. and Krause, M. and Krennrich, F. and Kumar, S. and Lang, M. J. and Maier, G. and McArthur, S. and McCann, A. and Meagher, K. and Moriarty, P. and Mukherjee, R. and Nguyen, T. and Nieto, D. and Ong, R. A. and Otte, A. N. and Park, N. and Petrashyk, A. and Pichel, A. and Pohl, Martin and Popkow, A. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Rovero, A. C. and Rulten, C. and Sadeh, I. and Santander, Marcos and Sembroski, G. H. and Shahinyan, K. and Telezhinsky, Igor O. and Tucci, J. V. and Tyler, J. and Wakely, S. P. and Weinstein, A. and Wilhelm, Alina and Williams, D. A.},
  title     = {Very-High-Energy gamma-Ray Observations of the Blazar 1ES 2344+514 with VERITAS},
  series = {Monthly notices of the Royal Astronomical Society},
  volume    = {471},
  journal   = {Monthly notices of the Royal Astronomical Society},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0035-8711},
  doi       = {10.1093/mnras/stx1756},
  pages     = {2117 -- 2123},
  year      = {2017},
  abstract  = {We present very-high-energy gamma-ray observations of the BL Lac object 1ES 2344+514 taken by the Very Energetic Radiation Imaging Telescope Array System between 2007 and 2015. 1ES 2344+514 is detected with a statistical significance above the background of 20.8 sigma in 47.2 h (livetime) of observations, making this the most comprehensive very-high-energy study of 1ES 2344+514 to date. Using these observations, the temporal properties of 1ES 2344+514 are studied on short and long times-scales. We fit a constant-flux model to nightly and seasonally binned light curves and apply a fractional variability test to determine the stability of the source on different time-scales. We reject the constant-flux model for the 2007-2008 and 2014-2015 nightly binned light curves and for the long-term seasonally binned light curve at the > 3 sigma level. The spectra of the time-averaged emission before and after correction for attenuation by the extragalactic background light are obtained. The observed time-averaged spectrum above 200 GeV is satisfactorily fitted (x(2)/NDF = 7.89/6) by a power-law function with an index Gamma = 2.46 +/- 0.06(stat) +/- 0.20(sys) and extends to at least 8 TeV. The extragalactic-backgroundlight-deabsorbed spectrum is adequately fit (x(2)/NDF = 6.73/6) by a power-law function with an index Gamma = 2.15 +/- 0.06(stat) +/- 0.20(sys) while an F-test indicates that the power law with an exponential cut-off function provides a marginally better fit (x(2)/NDF = 2.56/5) at the 2.1 sigma level. The source location is found to be consistent with the published radio location and its spatial extent is consistent with a point source.},
  language  = {en}
}