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Abeysekara, A. U. ; Archambault, S. ; Archer, A. ; Benbow, Wystan ; Bird, Ralph ; Buchovecky, M. ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cerruti, M. ; Chen, X. ; Ciupik, L. ; Cui, W. ; Dickinson, H. J. ; Eisch, J. D. ; Errando, M. ; Falcone, A. ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Fortson, L. ; Furniss, A. ; Gillanders, G. H. ; Griffin, S. ; Grube, J. ; Hutten, M. ; Hakansson, N. ; Hanna, D. ; Holder, J. ; Humensky, T. B. ; Johnson, C. A. ; Kaaret, P. ; Kar, P. ; Kertzman, M. ; Kieda, D. ; Krause, M. ; Krennrich, F. ; Kumar, S. ; Lang, M. J. ; Maier, G. ; McArthur, S. ; McCann, A. ; Meagher, K. ; Moriarty, P. ; Mukherjee, R. ; Nguyen, T. ; Nieto, D. ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Pelassa, V. ; Pohl, Martin ; Popkow, A. ; Pueschel, Elisa ; Quinn, J. ; Ragan, K. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Rulten, C. ; Santander, M. ; Sembroski, G. H. ; Shahinyan, K. ; Staszak, D. ; Telezhinsky, Igor O. ; Tucci, J. V. ; Tyler, J. ; Wakely, S. P. ; Weiner, O. M. ; Weinstein, A. ; Wilhelm, Alina ; Williams, D. A. ; Fegan, S. ; Giebels, B. ; Horan, D. ; Berdyugin, A. ; Kuan, J. ; Lindfors, E. ; Nilsson, K. ; Oksanen, A. ; Prokoph, H. ; Reinthal, R. ; Takalo, L. ; Zefi, F.
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.
Abeysekara, A. U. ; Archambault, S. ; Archer, A. ; Benbow, W. ; Bird, R. ; Buchovecky, M. ; Buckley, J. H. ; Byrum, K. ; Cardenzana, J. V. ; Cerruti, M. ; Chen, Xuhui ; Christiansen, J. L. ; Ciupik, L. ; Cui, W. ; Dickinson, H. J. ; Eisch, J. D. ; Errando, M. ; Falcone, A. ; Fegan, D. J. ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Fortin, P. ; Fortson, L. ; Furniss, A. ; Gillanders, G. H. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Huetten, M. ; Hakansson, Nils ; Hanna, D. ; Holder, J. ; Humensky, T. B. ; Johnson, C. A. ; Kaaret, P. ; Kar, P. ; Kelley-Hoskins, N. ; Kertzman, M. ; Kieda, D. ; Krause, M. ; Krennrich, F. ; Kumar, S. ; Lang, M. J. ; Lin, T. T. Y. ; Maier, G. ; McArthur, S. ; McCann, A. ; Meagher, K. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Perkins, J. S. ; Petrashyk, A. ; Pohl, Martin ; Popkow, A. ; Pueschel, Elisa ; Quinn, J. ; Ragan, K. ; Ratliff, G. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Santander, M. ; Sembroski, G. H. ; Shahinyan, K. ; Staszak, D. ; Telezhinsky, Igor O. ; Tucci, J. V. ; Tyler, J. ; Vincent, S. ; Wakely, S. P. ; Weiner, O. M. ; Weinstein, A. ; Williams, D. A. ; Zitzer, B.
The F-type star KIC. 8462852 has recently been identified as an exceptional target for search for extraterrestrial intelligence (SETI) observations. We describe an analysis methodology for optical SETI, which we have used to analyze nine hours of serendipitous archival observations of KIC. 8462852 made with the VERITAS gamma-ray observatory between 2009 and 2015. No evidence of pulsed optical beacons, above a pulse intensity at the Earth of approximately 1 photon m(-2), is found. We also discuss the potential use of imaging atmospheric Cherenkov telescope arrays in searching for extremely short duration optical transients in general.
A Search for Pulsed Very High-energy Gamma-Rays from 13 Young Pulsars in Archival VERITAS Data
(2019)
Archer, A. ; Benbow, Wystan ; Bird, Ralph ; Brose, Robert ; Buchovecky, M. ; Buckley, J. H. ; Chromey, A. J. ; Cui, Wei ; Falcone, A. ; Feng, Qi ; Finley, J. P. ; Fortson, Lucy ; Furniss, Amy ; Gent, A. ; Gueta, O. ; Hanna, David ; Hassan, T. ; Hervet, Olivier ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Johnson, Caitlin A. ; Kaaret, Philip ; Kar, P. ; Kelley-Hoskins, N. ; Kertzman, M. ; Kieda, David ; Krennrich, F. ; Kumar, S. ; Lang, M. J. ; Lin, T. T. Y. ; McCann, A. ; Moriarty, P. ; Mukherjee, Reshmi ; Ong, R. A. ; Otte, Adam Nepomuk ; Pandel, D. ; Park, N. ; Petrashyk, A. ; Pohl, Martin ; Pueschel, Elisa ; Quinn, J. ; Ragan, K. ; Richards, Gregory T. ; Roache, E. ; Sadeh, I ; Santander, Marcos ; Scott, S. S. ; Sembroski, G. H. ; Shahinyan, Karlen ; Sushch, Iurii ; Tyler, J. ; Wakely, S. P. ; Weinstein, A. ; Wells, R. M. ; Wilcox, P. ; Wilhelm, Alina ; Williams, D. A. ; Williamson, T. J. ; Zitzer, B.
We conduct a search for periodic emission in the very high-energy (VHE) gamma-ray band (E > 100 GeV) from a total of 13 pulsars in an archival VERITAS data set with a total exposure of over 450 hr. The set of pulsars includes many of the brightest young gamma-ray pulsars visible in the Northern Hemisphere. The data analysis resulted in nondetections of pulsed VHE gamma-rays from each pulsar. Upper limits on a potential VHE gamma-ray flux are derived at the 95% confidence level above three energy thresholds using two methods. These are the first such searches for pulsed VHE emission from each of the pulsars, and the obtained limits constrain a possible flux component manifesting at VHEs as is seen for the Crab pulsar.
Abeysekara, A. U. ; Archer, A. ; Benbow, Wystan ; Bird, Ralph ; Brose, Robert ; Buchovecky, M. ; Bugaev, V. ; Connolly, M. P. ; Cui, Wei ; Errando, Manel ; Falcone, A. ; Feng, Qi ; Finley, John P. ; Flinders, A. ; Fortson, L. ; Furniss, Amy ; Gillanders, Gerard H. ; Huetten, M. ; Hanna, David ; Hervet, O. ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Johnson, Caitlin A. ; Kaaret, Philip ; Kar, P. ; Kelley-Hoskins, N. ; Kertzman, M. ; Kieda, David ; Krause, Maria ; Krennrich, F. ; Lang, M. J. ; Lin, T. T. Y. ; Maier, Gernot ; McArthur, S. ; Moriarty, P. ; Mukherjee, Reshmi ; Ong, R. A. ; Park, N. ; Perkins, Jeremy S. ; Petrashyk, A. ; Pohl, Martin ; Popkow, Alexis ; Pueschel, Elisa ; Quinn, J. ; Ragan, K. ; Reynolds, P. T. ; Richards, Gregory T. ; Roache, E. ; Rulten, C. ; Sadeh, I. ; Santander, M. ; Sembroski, G. H. ; Shahinyan, Karlen ; Tyler, J. ; Wakely, S. P. ; Weiner, O. M. ; Weinstein, A. ; Wells, R. M. ; Wilcox, P. ; Wilhelm, Alina ; Williams, David A. ; Zitzer, B. ; Vurm, Indrek ; Beloborodov, Andrei
On 2015 March 23, the Very Energetic Radiation Imaging Telescope Array System (VERITAS) responded to a Swift-Burst Alert Telescope (BAT) detection of a gamma-ray burst, with observations beginning 270 s after the onset of BAT emission, and only 135 s after the main BAT emission peak. No statistically significant signal is detected above 140 GeV. The VERITAS upper limit on the fluence in a 40-minute integration corresponds to about 1% of the prompt fluence. Our limit is particularly significant because the very-high-energy (VHE) observation started only similar to 2 minutes after the prompt emission peaked, and Fermi-Large Area Telescope observations of numerous other bursts have revealed that the high-energy emission is typically delayed relative to the prompt radiation and lasts significantly longer. Also, the proximity of GRB 150323A (z = 0.593) limits the attenuation by the extragalactic background light to similar to 50% at 100-200 GeV. We conclude that GRB 150323A had an intrinsically very weak high-energy afterglow, or that the GeV spectrum had a turnover below similar to 100 GeV. If the GRB exploded into the stellar wind of a massive progenitor, the VHE non-detection constrains the wind density parameter to be A greater than or similar to 3 x 10(11) g . cm(-1), consistent with a standard Wolf-Rayet progenitor. Alternatively, the VHE emission from the blast wave would be weak in a very tenuous medium such as the interstellar medium, which therefore cannot be ruled out as the environment of GRB 150323A.
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 >.
Aliu, E. ; Aune, T. ; Barnacka, Anna ; Beilicke, M. ; Benbow, W. ; Berger, K. ; Biteau, Jonathan ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cardenzana, J. V. ; Cerruti, M. ; Chen, Xuhui ; Ciupik, L. ; Connaughton, V. ; Cui, W. ; Dickinson, H. J. ; Eisch, J. D. ; Errando, M. ; Falcone, A. ; Federici, Simone ; 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. ; Hakansson, Nils ; Hanna, D. ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Johnson, C. A. ; Kaaret, P. ; Kar, P. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Madhavan, A. S. ; Maier, G. ; McArthur, S. ; McCann, A. ; Meagher, K. ; Millis, J. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Pohl, Martin ; Popkow, A. ; Prokoph, H. ; Pueschel, Elisa ; Quinn, J. ; Ragan, K. ; Rajotte, J. ; Reyes, L. C. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Sembroski, G. H. ; Shahinyan, K. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Tucci, J. V. ; Tyler, J. ; Varlotta, A. ; Vassiliev, V. V. ; Vincent, S. ; Wakely, S. P. ; Weiner, O. M. ; Weinstein, A. ; Welsing, R. ; Wilhelm, Alina ; Williams, D. A. ; Zitzer, B. ; McEnery, J. E. ; Perkins, J. S. ; Veres, P. ; Zhu, S.
Prompt emission from the very fluent and nearby (z = 0.34) gamma-ray burst GRB130427A was detected by several orbiting telescopes and by ground-based, wide-field-of-view optical transient monitors. Apart from the intensity and proximity of this GRB, it is exceptional due to the extremely long-lived high-energy (100 MeV to 100 GeV) gamma-ray emission, which was detected by the Large Area Telescope on the Fermi Gamma-Ray Space Telescope for similar to 70 ks after the initial burst. The persistent, hard-spectrum, high-energy emission suggests that the highest-energy gamma rays may have been produced via synchrotron self-Compton processes though there is also evidence that the high-energy emission may instead be an extension of the synchrotron spectrum. VERITAS, a ground-based imaging atmospheric Cherenkov telescope array, began follow-up observations of GRB130427A similar to 71 ks (similar to 20 hr) after the onset of the burst. The GRB was not detected with VERITAS; however, the high elevation of the observations, coupled with the low redshift of the GRB, make VERITAS a very sensitive probe of the emission from GRB130427A for E > 100 GeV. The non-detection and consequent upper limit derived place constraints on the synchrotron self-Compton model of high-energy gamma-ray emission from this burst.
Archambault, S. ; Aune, T. ; Behera, B. ; Beilicke, M. ; Benbow, W. ; Berger, K. ; Bird, R. ; Biteau, Jonathan ; Bugaev, V. ; Byrum, K. ; Cardenzana, J. V. ; Cerruti, M. ; Chen, Xuhui ; Ciupik, L. ; Connolly, M. P. ; Cui, Wei ; Dumm, J. ; Errando, M. ; Falcone, A. ; Federici, Simone ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; 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. ; Kumar, S. ; Lang, M. J. ; Madhavan, A. S. ; Maier, G. ; McCann, A. ; Meagher, K. ; Moriarty, P. ; Mukherjee, R. ; Nieto, Daniel ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Pohl, Martin ; Popkow, A. ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Rajotte, J. ; Reyes, L. C. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Sembroski, G. H. ; Shahinyan, K. ; Staszak, D. ; Telezhinsky, Igor O. ; Tucci, J. V. ; Tyler, J. ; Varlotta, A. ; Vassiliev, V. V. ; Vincent, S. ; Wakely, S. P. ; Weinstein, A. ; Welsing, R. ; Wilhelm, Alina ; Williams, D. A. ; Ackermann, Margit ; Ajello, M. ; Albert, A. ; Baldini, L. ; Bastieri, D. ; Bellazzini, R. ; Bissaldi, E. ; Bregeon, Johan ; Buehler, R. ; Buson, S. ; Caliandro, G. A. ; Cameron, R. A. ; Caraveo, P. A. ; Cavazzuti, E. ; Charles, E. ; Chiang, J. ; Ciprini, S. ; Claus, R. ; Cutini, S. ; de Angelis, A. ; de Palma, F. ; Dermer, C. D. ; Digel, S. W. ; Di Venere, L. ; Drell, P. S. ; Favuzzi, C. ; Franckowiak, A. ; Fusco, P. ; Gargano, F. ; Gasparrini, D. ; Giglietto, N. ; Giordano, F. ; Giroletti, M. ; Grenier, I. A. ; Guiriec, S. ; Jogler, T. ; Kuss, M. ; Larsson, S. ; Latronico, L. ; Longo, F. ; Loparco, F. ; Lubrano, P. ; Madejski, G. M. ; Mayer, M. ; Mazziotta, Mario Nicola ; Michelson, P. F. ; Mizuno, T. ; Monzani, M. E. ; Morselli, Aldo ; Murgia, S. ; Nuss, E. ; Ohsugi, T. ; Ormes, J. F. ; Paneque, D. ; Perkins, J. S. ; Piron, F. ; Pivato, G. ; Raino, S. ; Razzano, M. ; Reimer, A. ; Reimer, Olaf ; Ritz, S. ; Schaal, M. ; Sgro, C. ; Siskind, E. J. ; Spinelli, P. ; Takahashi, H. ; Tibaldo, L. ; Tinivella, M. ; Troja, E. ; Vianello, G. ; Werner, M. ; Wood, M.
We present deep VERITAS observations of the blazar PKS 1424+240, along with contemporaneous Fermi Large Area Telescope, Swift X-ray Telescope, and Swift UV Optical Telescope data between 2009 February 19 and 2013 June 8. This blazar resides at a redshift of z >= 0.6035, displaying a significantly attenuated gamma-ray flux above 100 GeV due to photon absorption via pair-production with the extragalactic background light. We present more than 100 hr of VERITAS observations over three years, a multiwavelength light curve, and the contemporaneous spectral energy distributions. The source shows a higher flux of (2.1 +/- 0.3) x 10(-7) photons m(-2) s(-1) above 120 GeV in 2009 and 2011 as compared to the flux measured in 2013, corresponding to (1.02 +/- 0.08) x 10-7 photons m(-2) s(-1) above 120 GeV. The measured differential very high energy (VHE; E >= 100 GeV) spectral indices are Gamma = 3.8 +/- 0.3, 4.3 +/- 0.6 and 4.5 +/- 0.2 in 2009, 2011, and 2013, respectively. No significant spectral change across the observation epochs is detected. We find no evidence for variability at gamma-ray opacities of greater than tau = 2, where it is postulated that any variability would be small and occur on timescales longer than a year if hadronic cosmic-ray interactions with extragalactic photon fields provide a secondary VHE photon flux. The data cannot rule out such variability due to low statistics.
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. 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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.