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Archer, A. ; Benbow, W. ; Bird, R. ; Brose, Robert ; Buchovecky, M. ; Bugaev, V. ; Connolly, M. P. ; Cui, W. ; Daniel, M. K. ; Falcone, A. ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Fortson, L. ; Furniss, A. ; Hanna, D. ; Hervet, O. ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Hutten, M. ; Johnson, C. A. ; Kaaret, P. ; Kelley-Hoskins, N. ; Kieda, D. ; Krause, M. ; Krennrich, F. ; Kumar, S. ; Lang, M. J. ; Maier, G. ; McArthur, S. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Petrashyk, A. ; Pohl, Martin ; Popkow, A. ; Pueschel, Elisa ; Quinn, J. ; Ragan, K. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Rulten, C. ; Sadeh, I. ; Tyler, J. ; Wakely, S. P. ; Weiner, O. M. ; Wilcox, P. ; Wilhelm, Alina ; Williams, D. A. ; Wissel, S. A. ; Zitzer, B.
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.
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.
Archambault, S. ; Archer, A. ; Benbow, Wystan ; Bird, Ralph ; Bourbeau, E. ; Buchovecky, M. ; Buckley, J. H. ; Bugaev, V. ; Cerruti, M. ; Connolly, M. P. ; Cui, W. ; Dwarkadas, Vikram V. ; Errando, M. ; Falcone, A. ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Fortson, L. ; Furniss, A. ; Griffin, S. ; Huetten, M. ; Hanna, D. ; Holder, J. ; Johnson, C. A. ; Kaaret, P. ; Kar, P. ; Kelley-Hoskins, N. ; Kertzman, M. ; Kieda, D. ; Krause, M. ; Kumar, S. ; Lang, M. J. ; Maier, G. ; McArthur, S. ; McCann, A. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Ong, R. A. ; Otte, A. N. ; Park, Nahee ; Pohl, Martin ; Popkow, A. ; Pueschel, Elisa ; Quinn, J. ; Ragan, K. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Sadeh, I. ; Santander, M. ; Sembroski, G. H. ; Shahinyan, K. ; Slane, P. ; Staszak, D. ; Telezhinsky, Igor O. ; Trepanier, S. ; Tyler, J. ; Wakely, S. P. ; Weinstein, A. ; Weisgarber, T. ; Wilcox, P. ; Wilhelm, Alina ; Williams, D. A. ; Zitzer, B.
Multiwavelength observations of the AGN 1ES 0414+009 with veritas, FERMI-LAT, SWIFT-XRT, AND MDM
(2012)
Aliu, E. ; Archambault, S. ; Arlen, T. ; Aune, T. ; Beilicke, M. ; Benbow, W. ; Boettcher, Markus ; Bouvier, A. ; Bugaev, V. ; Cannon, A. ; Cesarini, A. ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Cui, W. ; Dickherber, R. ; Dumm, J. ; Errando, M. ; Falcone, A. ; Federici, Stefania ; 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. ; Holder, J. ; Huan, H. ; Hughes, G. ; Hui, C. M. ; Imran, A. ; Jameil, O. ; Kaaret, P. ; Karlsson, N. ; Kertzman, M. ; Kerr, J. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Lee, K. ; Madhavan, A. S. ; 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. ; Pichel, A. ; Pohl, Martin ; Quinn, J. ; Ragan, K. ; Reynolds, P. T. ; Roache, E. ; Ruppel, J. ; Saxon, D. B. ; Schroedter, M. ; Sembroski, G. H. ; Sentuerk, G. D. ; Smith, A. W. ; Staszak, D. ; Stroh, M. ; Telezhinsky, Igor O. ; Tesic, G. ; Theiling, M. ; Thibadeau, S. ; Tsurusaki, K. ; Varlotta, A. ; Vassiliev, V. V. ; Vivier, M. ; Wakely, S. P. ; Ward, J. E. ; Weinstein, A. ; Welsing, R. ; Williams, D. A. ; Zitzer, B.
We present observations of the BL Lac object 1ES 0414+009 in the >200 GeV gamma-ray band by the VERITAS array of Cherenkov telescopes. 1ES 0414+009 was observed by VERITAS between 2008 January and 2011 February, resulting in 56.2 hr of good quality pointed observations. These observations resulted in a detection of 822 events from the source corresponding to a statistical significance of 6.4 standard deviations (6.4 sigma) above the background. The source flux, showing no evidence for variability, is measured as (5.2 +/- 1.1(stat) +/- 2.6(sys)) x 10(-12) photons cm(-2) s(-1) above 200 GeV, equivalent to approximately 2% of the Crab Nebula flux above this energy. The differential photon spectrum from 230 GeV to 850 GeV is well fit by a power law with a photon index of Gamma = 3.4 +/- 0.5(stat) +/- 0.3(sys) and a flux normalization of (1.6 +/- 0.3(stat) +/- 0.8(sys)) x 10(-11) photons cm(-2) s(-1) at 300 GeV. We also present multiwavelength results taken in the optical (MDM), x-ray (Swift-XRT), and GeV (Fermi-LAT) bands and use these results to construct a broadband spectral energy distribution (SED). Modeling of this SED indicates that homogenous one-zone leptonic scenarios are not adequate to describe emission from the system, with a lepto-hadronic model providing a better fit to the data.
Aliu, E. ; Archambault, S. ; Aune, T. ; Behera, B. ; Beilicke, M. ; Benbow, W. ; Berger, K. ; Bird, R. ; Buckley, J. H. ; Bugaev, V. ; Cardenzana, J. V. ; Cerruti, M. ; Chen, Xuhui ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Cui, W. ; Dumm, J. ; Dwarkadas, Vikram V. ; Errando, M. ; Falcone, A. ; Federici, Simone ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Fortin, P. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gall, D. ; 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. ; Madhavan, A. S. ; Maier, G. ; McCann, A. J. ; Meagher, K. ; Millis, J. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Ong, R. A. ; Otte, A. N. ; Pandel, D. ; Park, N. ; Pohl, Martin ; Popkow, A. ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Rajotte, J. ; Ratliff, G. ; Reyes, L. C. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Rousselle, J. ; Sembroski, G. H. ; Shahinyan, K. ; Sheidaei, F. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Tsurusaki, K. ; Tucci, J. V. ; Tyler, J. ; Varlotta, A. ; Vassiliev, V. V. ; Vincent, S. ; Wakely, S. P. ; Ward, J. E. ; Weinstein, A. ; Welsing, R. ; Wilhelm, Alina
We report on deep observations of the extended TeV gamma-ray source MGRO J1908+06 made with the VERITAS very high energy gamma-ray observatory. Previously, the TeV emission has been attributed to the pulsar wind nebula (PWN) of the Fermi-LAT pulsar PSR J1907+0602. We detect MGRO J1908+06 at a significance level of 14 standard deviations (14 sigma) and measure a photon index of 2.20 +/- 0.10(stat) +/- 0.20(sys). The TeV emission is extended, covering the region near PSR J1907+0602 and also extending toward SNR G40.5-0.5. When fitted with a two-dimensional Gaussian, the intrinsic extension has a standard deviation of sigma(src) = 0 degrees.44 +/- 0 degrees.02. In contrast to other TeV PWNe of similar age in which the TeV spectrum softens with distance from the pulsar, the TeV spectrum measured near the pulsar location is consistent with that measured at a position near the rim of G40.5-0.5, 0 degrees.33 away.
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.
Archer, A. ; Benbow, W. ; Bird, R. ; Buchovecky, M. ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cardenzana, J. V. ; Cerruti, M. ; Chen, Xuhui ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Eisch, J. D. ; Falcone, A. ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Flinders, A. ; Fortson, L. ; Furniss, A. ; Gillanders, G. H. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Hakansson, Nils ; Hanna, D. ; Holder, J. ; Humensky, T. B. ; Huetten, M. ; Johnson, C. A. ; Kaaret, P. ; Kar, P. ; Kelley-Hoskins, N. ; Kertzman, M. ; Kieda, D. ; Krause, M. ; Krennrich, F. ; Kumar, S. ; Lang, M. J. ; McArthur, S. ; McCann, A. ; Meagher, K. ; Millis, J. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Ong, R. A. ; Park, N. ; Pelassa, V. ; Pohl, Martin ; Popkow, A. ; Pueschel, Elisa ; Quinn, J. ; Ragan, K. ; Ratliff, G. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Rousselle, J. ; Santander, M. ; Sembroski, G. H. ; Shahinyan, K. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Tucci, J. V. ; Tyler, J. ; Vassiliev, V. V. ; Wakely, S. P. ; Weiner, O. M. ; Weinstein, A. ; Wilhelm, Alina ; Williams, D. A. ; Zitzer, B. ; Yusef-Zadeh, F.
The Galactic Center ridge has been observed extensively in the past by both GeV and TeV gamma-ray instruments revealing a wealth of structure, including a diffuse component and the point sources G0.9+0.1 (a composite supernova remnant) and Sgr A* (believed to be associated with the supermassive black hole located at the center of our Galaxy). Previous very high energy (VHE) gamma-ray observations with the H.E.S.S.. experiment have also detected an extended TeV gamma-ray component along the Galactic plane in the >300 GeV gamma-ray regime. Here we report on observations of the Galactic Center ridge from 2010 to 2014 by the VERITAS telescope array in the >2 TeV energy range. From these observations we (1) provide improved measurements of the differential energy spectrum for Sgr A* in the >2 TeV gamma-ray regime, (2) provide a detection in the >2 TeV gamma-ray emission from the composite SNR G0.9+0.1 and an improved determination of its multi-TeV gamma-ray energy spectrum, and. (3) report on the detection of VER J1746-289, a localized enhancement of >2 TeV gamma-ray emission along the Galactic plane.