TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archambault, S.
A1  - Archer, A.
A1  - Benbow, W.
A1  - Bird, R.
A1  - Biteau, Jonathan
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Byrum, K.
A1  - Cardenzana, J. V.
A1  - Cerruti, M.
A1  - Chen, Xuhui
A1  - Christiansen, J. L.
A1  - Ciupik, L.
A1  - Connolly, M. P.
A1  - Cui, W.
A1  - Dickinson, H. J.
A1  - Dumm, J.
A1  - Eisch, J. D.
A1  - Errando, M.
A1  - Falcone, A.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Fleischhack, H.
A1  - Flinders, A.
A1  - Fortin, P.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Gillanders, G. H.
A1  - Griffin, S.
A1  - Grube, J.
A1  - Gyuk, G.
A1  - Huetten, M.
A1  - Hanna, D.
A1  - Holder, J.
A1  - Humensky, T. B.
A1  - Johnson, C. A.
A1  - Kaaret, P.
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Krause, M.
A1  - Krennrich, F.
A1  - Lang, M. J.
A1  - Maier, G.
A1  - McArthur, S.
A1  - McCann, A.
A1  - Meagher, K.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Nieto, D.
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Pelassa, V.
A1  - Petrashyk, A.
A1  - Petry, D.
A1  - Pohl, Martin
A1  - Popkow, A.
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Ratliff, G.
A1  - Reyes, L. C.
A1  - Reynolds, P. T.
A1  - Reynolds, K.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, K.
A1  - Smith, A. W.
A1  - Staszak, D.
A1  - Telezhinsky, Igor O.
A1  - Tucci, J. V.
A1  - Tyler, J.
A1  - Vincent, S.
A1  - Wakely, S. P.
A1  - Weiner, O. M.
A1  - Weinstein, A.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Zitzer, B.
T1  - VERITAS and multiwavelength observations of the BL Lacertae object 1ES 1741+196
JF  - Monthly notices of the Royal Astronomical Society
N2  - We present results from multiwavelength observations of the BL Lacertae object 1ES 1741 + 196, including results in the very high energy gamma-ray regime using the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The VERITAS time-averaged spectrum, measured above 180 GeV, is well modelled by a power law with a spectral index of 2.7 +/- 0.7(stat) +/- 0.2(syst). The integral flux above 180 GeV is (3.9 +/- 0.8(stat) +/- 1.0(syst)) x 10(-8) m(-2) s(-1), corresponding to 1.6 per cent of the Crab nebula flux on average. The multiwavelength spectral energy distribution of the source suggests that 1ES 1741+196 is an extreme-high-frequency-peaked BL Lacertae object. The observations analysed in this paper extend over a period of six years, during which time no strong flares were observed in any band. This analysis is therefore one of the few characterizations of a blazar in a non-flaring state.
KW  - astroparticle physics
KW  - relativistic processes
KW  - galaxies: individual: 1ES 1741+196=VER J1744+195
Y1  - 2016
U6  - https://doi.org/10.1093/mnras/stw664
SN  - 0035-8711
SN  - 1365-2966
VL  - 459
SP  - 2550
EP  - 2557
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archambault, S.
A1  - Archer, A.
A1  - Benbow, W.
A1  - Bird, R.
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Cerruti, M.
A1  - Connolly, M. P.
A1  - Cui, W.
A1  - Falcone, A.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Fleischhack, H.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Gillanders, G. H.
A1  - Griffin, S.
A1  - Grube, J.
A1  - Huetten, M.
A1  - Hanna, D.
A1  - Hervet, O.
A1  - Holder, J.
A1  - Humensky, T. B.
A1  - Johnson, C. A.
A1  - Kaaret, P.
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Krause, M.
A1  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Maier, G.
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Nieto, D.
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Popkow, A.
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, K.
A1  - Staszak, D.
A1  - Telezhinsky, Igor O.
A1  - Tyler, J.
A1  - Vassiliev, V. V.
A1  - Wakely, S. P.
A1  - Weiner, O. M.
A1  - Weinstein, A.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Zitzer, B.
T1  - Discovery of Very-high-energy Emission from RGB J2243+203 and Derivation of Its Redshift Upper Limit
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series
N2  - Very-high-energy (VHE; > 100 GeV) gamma-ray emission from the blazar RGB J2243+203 was discovered with the VERITAS Cherenkov telescope array, during the period between 2014 December 21 and 24. The VERITAS energy spectrum from this source can be fitted by a power law with a photon index of 4.6 +/- 0.5, and a flux normalization at 0.15 TeV of (6.3 +/- 1.1) x 10(-10) cm(-2) s(-1) TeV-1. The integrated Fermi-LAT flux from 1 to 100 GeV during the VERITAS detection is (4.1 +/- 0.8) x 10(-8) cm(-2) s(-1), which is an order of magnitude larger than the four-year-averaged flux in the same energy range reported in the 3FGL catalog, (4.0 +/- 0.1 x 10(-9) cm(-2) s(-1)). The detection with VERITAS triggered observations in the X-ray band with the Swift-XRT. However, due to scheduling constraints Swift-XRT observations were performed 67 hr after the VERITAS detection, rather than simultaneously with the VERITAS observations. The observed X-ray energy spectrum between 2 and 10 keV can be fitted with a power law with a spectral index of 2.7 +/- 0.2, and the integrated photon flux in the same energy band is (3.6 +/- 0.6) x 10(-13) cm(-2) s(-1). EBL-model-dependent upper limits of the blazar redshift have been derived. Depending on the EBL model used, the upper limit varies in the range from z < 0.9 to z < 1.1.
KW  - galaxies: individual (RGB J2243+203)
Y1  - 2017
U6  - https://doi.org/10.3847/1538-4365/aa8d76
SN  - 0067-0049
SN  - 1538-4365
VL  - 233
SP  - 1188
EP  - 1204
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archambault, S.
A1  - Archer, A.
A1  - Benbow, W.
A1  - Bird, R.
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Byrum, K.
A1  - Cardenzana, J. V.
A1  - Cerruti, M.
A1  - Chen, Xuhui
A1  - Christiansen, J. L.
A1  - Ciupik, L.
A1  - Cui, W.
A1  - Dickinson, H. J.
A1  - Eisch, J. D.
A1  - Errando, M.
A1  - Falcone, A.
A1  - Fegan, D. J.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Fleischhack, H.
A1  - Fortin, P.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Gillanders, G. H.
A1  - Griffin, S.
A1  - Grube, J.
A1  - Gyuk, G.
A1  - Huetten, M.
A1  - Hakansson, Nils
A1  - Hanna, D.
A1  - Holder, J.
A1  - Humensky, T. B.
A1  - Johnson, C. A.
A1  - Kaaret, P.
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Krause, M.
A1  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - Maier, G.
A1  - McArthur, S.
A1  - McCann, A.
A1  - Meagher, K.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Nieto, D.
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Perkins, J. S.
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Popkow, A.
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Ratliff, G.
A1  - Reynolds, P. T.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, K.
A1  - Staszak, D.
A1  - Telezhinsky, Igor O.
A1  - Tucci, J. V.
A1  - Tyler, J.
A1  - Vincent, S.
A1  - Wakely, S. P.
A1  - Weiner, O. M.
A1  - Weinstein, A.
A1  - Williams, D. A.
A1  - Zitzer, B.
T1  - A SEARCH FOR BRIEF OPTICAL FLASHES ASSOCIATED WITH THE SETI TARGET KIC 8462852
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters
N2  - 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.
KW  - astrobiology
KW  - extraterrestrial intelligence
KW  - methods: observational
KW  - stars: individual ( KIC 8462852)
KW  - techniques: photometric
Y1  - 2016
U6  - https://doi.org/10.3847/2041-8205/818/2/L33
SN  - 2041-8205
SN  - 2041-8213
VL  - 818
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archambault, S.
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Byrum, K.
A1  - Cerruti, M.
A1  - Chen, X.
A1  - Ciupik, L.
A1  - Cui, W.
A1  - Dickinson, H. J.
A1  - Eisch, J. D.
A1  - Errando, M.
A1  - Falcone, A.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Fleischhack, H.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Gillanders, G. H.
A1  - Griffin, S.
A1  - Grube, J.
A1  - Hutten, M.
A1  - Hakansson, N.
A1  - Hanna, D.
A1  - Holder, J.
A1  - Humensky, T. B.
A1  - Johnson, C. A.
A1  - Kaaret, P.
A1  - Kar, P.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Krause, M.
A1  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Maier, G.
A1  - McArthur, S.
A1  - McCann, A.
A1  - Meagher, K.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Nguyen, T.
A1  - Nieto, D.
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Pelassa, V.
A1  - Pohl, Martin
A1  - Popkow, A.
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, K.
A1  - Staszak, D.
A1  - Telezhinsky, Igor O.
A1  - Tucci, J. V.
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weiner, O. M.
A1  - Weinstein, A.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Fegan, S.
A1  - Giebels, B.
A1  - Horan, D.
A1  - Berdyugin, A.
A1  - Kuan, J.
A1  - Lindfors, E.
A1  - Nilsson, K.
A1  - Oksanen, A.
A1  - Prokoph, H.
A1  - Reinthal, R.
A1  - Takalo, L.
A1  - Zefi, F.
T1  - A Luminous and Isolated Gamma-Ray Flare from the Blazar B2 1215+30
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - 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.
KW  - BL Lacertae objects: individual (B2 1215+30, VER J1217+301)
KW  - galaxies: active
KW  - galaxies: jets
KW  - galaxies: nuclei
KW  - gamma rays: galaxies
Y1  - 2017
U6  - https://doi.org/10.3847/1538-4357/836/2/205
SN  - 0004-637X
SN  - 1538-4357
VL  - 836
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archer, A.
A1  - Aune, Taylor
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Bugaev, V.
A1  - Cui, Wei
A1  - Daniel, M. K.
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, John P.
A1  - Fleischhack, H.
A1  - Flinders, A.
A1  - Fortson, L.
A1  - Furniss, Amy
A1  - Gotthelf, Eric V.
A1  - Grube, J.
A1  - Hanna, David
A1  - Hervet, O.
A1  - Holder, J.
A1  - Huang, K.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Huetten, M.
A1  - Johnson, Caitlin A.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, David
A1  - Krause, Maria
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - Maier, Gernot
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Ong, R. A.
A1  - Otte, Adam Nepomuk
A1  - Pandel, Dirk
A1  - Park, Nahee
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Popkow, Alexis
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Rousselle, J.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Tyler, J.
A1  - Vassiliev, V. V.
A1  - Wakely, S. P.
A1  - Ward, J. E.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, David A.
A1  - Zitzer, B.
T1  - A Very High Energy gamma-Ray Survey toward the Cygnus Region of the Galaxy
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We present results from deep observations toward the Cygnus region using 300 hr of very high energy (VHE)gamma-ray data taken with the VERITAS Cerenkov telescope array and over 7 yr of high-energy.-ray data taken with the Fermi satellite at an energy above 1 GeV. As the brightest region of diffuse gamma-ray emission in the northern sky, the Cygnus region provides a promising area to probe the origins of cosmic rays. We report the identification of a potential Fermi-LAT counterpart to VER J2031+415 (TeV J2032+4130) and resolve the extended VHE source VER J2019+368 into two source candidates (VER J2018+367* and VER J2020+368*) and characterize their energy spectra. The Fermi-LAT morphology of 3FGL J2021.0+4031e (the Gamma Cygni supernova remnant) was examined, and a region of enhanced emission coincident with VER J2019+407 was identified and jointly fit with the VERITAS data. By modeling 3FGL J2015.6+3709 as two sources, one located at the location of the pulsar wind nebula CTB 87 and one at the quasar QSO J2015+371, a continuous spectrum from 1 GeV to 10 TeV was extracted for VER J2016+371 (CTB 87). An additional 71 locations coincident with Fermi-LAT sources and other potential objects of interest were tested for VHE gamma-ray emission, with no emission detected and upper limits on the differential flux placed at an average of 2.3% of the Crab Nebula flux. We interpret these observations in a multiwavelength context and present the most detailed gamma-ray view of the region to date.
KW  - acceleration of particles
KW  - cosmic rays
KW  - gamma rays: general
KW  - ISM: supernova remnants
Y1  - 2018
U6  - https://doi.org/10.3847/1538-4357/aac4a2
SN  - 0004-637X
SN  - 1538-4357
VL  - 861
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brill, A.
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Calderon-Madera, D.
A1  - Christiansen, J. L.
A1  - Cui, W.
A1  - Daniel, M. K.
A1  - Falcone, A.
A1  - Feng, Q.
A1  - Fernandez-Alonso, M.
A1  - Finley, J. P.
A1  - Fortson, Lucy
A1  - Furniss, Amy
A1  - Gent, A.
A1  - Giuri, C.
A1  - Gueta, O.
A1  - Hanna, David
A1  - Hassan, T.
A1  - Hervet, Oliver
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, Caitlin A.
A1  - Kaaret, P.
A1  - Kertzman, M.
A1  - Kieda, David
A1  - Krause, Maria
A1  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Maier, Gernot
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Nievas-Rosillo, M.
A1  - Ong, R. A.
A1  - Pfrang, Konstantin Johannes
A1  - Pohl, Martin
A1  - Prado, R. R.
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Ribeiro, D.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Rovero, A. C.
A1  - Sadeh, Iftach
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Sushch, Iurii
A1  - Svraka, T.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, Patrick
A1  - Wilhelm, Alina
A1  - Williams, David Arnold
A1  - Williamson, T. J.
A1  - Zitzer, B.
T1  - Measurement of the Extragalactic Background Light Spectral Energy Distribution with VERITAS
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - The extragalactic background light (EBL), a diffuse photon field in the optical and infrared range, is a record of radiative processes over the universe?s history. Spectral measurements of blazars at very high energies (>100 GeV) enable the reconstruction of the spectral energy distribution (SED) of the EBL, as the blazar spectra are modified by redshift- and energy-dependent interactions of the gamma-ray photons with the EBL. The spectra of 14 VERITAS-detected blazars are included in a new measurement of the EBL SED that is independent of EBL SED models. The resulting SED covers an EBL wavelength range of 0.56?56 ?m, and is in good agreement with lower limits obtained by assuming that the EBL is entirely due to radiation from cataloged galaxies.
KW  - Extragalactic astronomy
KW  - Active galactic nuclei
KW  - Diffuse radiation
KW  - Cosmology
Y1  - 2019
U6  - https://doi.org/10.3847/1538-4357/ab4817
SN  - 0004-637X
SN  - 1538-4357
VL  - 885
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brill, A.
A1  - Brose, Robert
A1  - Buckley, J. H.
A1  - Christiansen, Jessie L.
A1  - Chromey, A. J.
A1  - Daniel, M. K.
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, John P.
A1  - Fortson, L.
A1  - Furniss, Amy
A1  - Gillanders, Gerard H.
A1  - Gueta, O.
A1  - Hanna, David
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, Caitlin A.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, David
A1  - Krause, Maria
A1  - Krennrich, F.
A1  - Lang, M. J.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, Marcos
A1  - Scott, S. S.
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Williamson, T. J.
A1  - Zitzer, B.
A1  - Kaur, A.
T1  - VERITAS Observations of the BL Lac Object TXS 0506+056
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters
N2  - On 2017 September 22, the IceCube Neutrino Observatory reported the detection of the high-energy neutrino event IC 170922A, of potential astrophysical origin. It was soon determined that the neutrino direction was consistent with the location of the gamma-ray blazar TXS 0506+056. (3FGL J0509.4+ 0541), which was in an elevated gamma-ray emission state as measured by the Fermi satellite. Very Energetic Radiation Imaging Telescope Array System (VERITAS) observations of the neutrino/blazar region started on 2017 September 23 in response to the neutrino alert and continued through 2018 February 6. While no significant very-high-energy (VHE; E > 100 GeV) emission was observed from the blazar by VERITAS in the two-week period immediately following the IceCube alert, TXS 0506+ 056 was detected by VERITAS with a significance of 5.8 standard deviations (sigma) in the full 35 hr data set. The average photon flux of the source during this period was (8.9 +/- 1.6). x. 10(-12) cm(-2) s(-1), or 1.6% of the Crab Nebula flux, above an energy threshold of 110 GeV, with a soft spectral index of 4.8. +/-. 1.3.
KW  - astroparticle physics
KW  - BL Lacertae objects: individual (TXS 0506+056, VER J0509+057)
KW  - gamma rays: galaxies
KW  - quasars: general
KW  - neutrinos
Y1  - 2018
U6  - https://doi.org/10.3847/2041-8213/aad053
SN  - 2041-8205
SN  - 2041-8213
VL  - 861
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Chromey, A. J.
A1  - Connolly, M. P.
A1  - Cui, Wei
A1  - Daniel, M. K.
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, John P.
A1  - Fortson, L.
A1  - Furniss, Amy
A1  - Huetten, M.
A1  - Hanna, David
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, Caitlin A.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kertzman, M.
A1  - Kieda, David
A1  - Krause, M.
A1  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Ong, R. A.
A1  - Otte, Adam Nepomuk
A1  - Park, Nahee
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, Marcos
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Sushch, I.
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Williamson, T. J.
A1  - Zitzer, B.
A1  - Abdollahi, S.
A1  - Ajello, Marco
A1  - Baldini, Luca
A1  - Barbiellini, G.
A1  - Bastieri, Denis
A1  - Bellazzini, Ronaldo
A1  - Berenji, B.
A1  - Bissaldi, Elisabetta
A1  - Blandford, R. D.
A1  - Bonino, R.
A1  - Bottacini, E.
A1  - Brandt, Terri J.
A1  - Bruel, P.
A1  - Buehler, R.
A1  - Cameron, R. A.
A1  - Caputo, R.
A1  - Caraveo, P. A.
A1  - Castro, D.
A1  - Cavazzuti, E.
A1  - Charles, Eric
A1  - Chiaro, G.
A1  - Ciprini, S.
A1  - Cohen-Tanugi, Johann
A1  - Costantin, D.
A1  - Cutini, S.
A1  - de Palma, F.
A1  - Di Lalla, N.
A1  - Di Mauro, M.
A1  - Di Venere, L.
A1  - Dominguez, A.
A1  - Favuzzi, C.
A1  - Fegan, S. J.
A1  - Franckowiak, Anna
A1  - Fukazawa, Yasushi
A1  - Funk, Stefan
A1  - Fusco, Piergiorgio
A1  - Gargano, Fabio
A1  - Gasparrini, Dario
A1  - Giglietto, Nicola
A1  - Giordano, F.
A1  - Giroletti, Marcello
A1  - Green, D.
A1  - Grenier, I. A.
A1  - Guillemot, L.
A1  - Guiriec, Sylvain
A1  - Hays, Elizabeth
A1  - Hewitt, John W.
A1  - Horan, D.
A1  - Johannesson, G.
A1  - Kensei, S.
A1  - Kuss, M.
A1  - Larsson, Stefan
A1  - Latronico, L.
A1  - Lemoine-Goumard, Marianne
A1  - Li, J.
A1  - Longo, Francesco
A1  - Loparco, Francesco
A1  - Lovellette, M. N.
A1  - Lubrano, Pasquale
A1  - Magill, Jeffrey D.
A1  - Maldera, Simone
A1  - Mazziotta, Mario Nicola
A1  - McEnery, J. E.
A1  - Michelson, P. F.
A1  - Mitthumsiri, W.
A1  - Mizuno, Tsunefumi
A1  - Monzani, Maria Elena
A1  - Morselli, Aldo
A1  - Moskalenko, Igor V.
A1  - Negro, M.
A1  - Nuss, E.
A1  - Ojha, R.
A1  - Omodei, Nicola
A1  - Orienti, M.
A1  - Orlando, E.
A1  - Palatiello, M.
A1  - Paliya, Vaidehi S.
A1  - Paneque, D.
A1  - Perkins, Jeremy S.
A1  - Persic, M.
A1  - Pesce-Rollins, Melissa
A1  - Petrosian, Vahe'
A1  - Piron, F.
A1  - Porter, Troy A.
A1  - Principe, G.
A1  - Raino, S.
A1  - Rando, Riccardo
A1  - Rani, B.
A1  - Razzano, Massimilano
A1  - Razzaque, Soebur
A1  - Reimer, A.
A1  - Reimer, Olaf
A1  - Reposeur, T.
A1  - Sgro, C.
A1  - Siskind, E. J.
A1  - Spandre, Gloria
A1  - Spinelli, P.
A1  - Suson, D. J.
A1  - Tajima, Hiroyasu
A1  - Thayer, J. B.
A1  - Thompson, David J.
A1  - Torres, Diego F.
A1  - Tosti, Gino
A1  - Troja, Eleonora
A1  - Valverde, J.
A1  - Vianello, Giacomo
A1  - Vogel, M.
A1  - Wood, K.
A1  - Yassine, M.
A1  - Alfaro, R.
A1  - Alvarez, C.
A1  - Alvarez, J. D.
A1  - Arceo, R.
A1  - Arteaga-Velazquez, J. C.
A1  - Rojas, D. Avila
A1  - Ayala Solares, H. A.
A1  - Becerril, A.
A1  - Belmont-Moreno, E.
A1  - BenZvi, S. Y.
A1  - Bernal, A.
A1  - Braun, J.
A1  - Brisbois, C.
A1  - Caballero-Mora, K. S.
A1  - Capistran, T.
A1  - Carraminana, A.
A1  - Casanova, Sabrina
A1  - Castillo, M.
A1  - Cotti, U.
A1  - Cotzomi, J.
A1  - Coutino de Leon, S.
A1  - De Leon, C.
A1  - De la Fuente, E.
A1  - Dichiara, S.
A1  - Dingus, B. L.
A1  - DuVernois, M. A.
A1  - Diaz-Velez, J. C.
A1  - Engel, K.
A1  - Enriquez-Rivera, O.
A1  - Fiorino, D. W.
A1  - Fleischhack, H.
A1  - Fraija, N.
A1  - Garcia-Gonzalez, J. A.
A1  - Garfias, F.
A1  - Gonzalez Munoz, A.
A1  - Gonzalez, M. M.
A1  - Goodman, J. A.
A1  - Hampel-Arias, Z.
A1  - Harding, J. P.
A1  - Hernandez, S.
A1  - Hernandez-Almada, A.
A1  - Hona, B.
A1  - Hueyotl-Zahuantitla, F.
A1  - Hui, C. M.
A1  - Huntemeyer, P.
A1  - Iriarte, A.
A1  - Jardin-Blicq, A.
A1  - Joshi, V.
A1  - Kaufmann, S.
A1  - Lara, A.
A1  - Lauer, R. J.
A1  - Lee, W. H.
A1  - Lennarz, D.
A1  - Leon Vargas, H.
A1  - Linnemann, J. T.
A1  - Longinotti, A. L.
A1  - Luis-Raya, G.
A1  - Luna-Garcia, R.
A1  - Lopez-Coto, R.
A1  - Malone, K.
A1  - Marinelli, S. S.
A1  - Martinez, O.
A1  - Martinez-Castellanos, I.
A1  - Martinez-Castro, J.
A1  - Martinez-Huerta, H.
A1  - Matthews, J. A.
A1  - Miranda-Romagnoli, P.
A1  - Moreno, E.
A1  - Mostafa, M.
A1  - Nayerhoda, A.
A1  - Nellen, L.
A1  - Newbold, M.
A1  - Nisa, M. U.
A1  - Noriega-Papaqui, R.
A1  - Pelayo, R.
A1  - Pretz, J.
A1  - Perez-Perez, E. G.
A1  - Ren, Z.
A1  - Rho, C. D.
A1  - Riviere, C.
A1  - Rosa-Gonzalez, D.
A1  - Rosenberg, M.
A1  - Ruiz-Velasco, E.
A1  - Salazar, H.
A1  - Greus, F. Salesa
A1  - Sandoval, A.
A1  - Schneider, M.
A1  - Arroyo, M. Seglar
A1  - Sinnis, G.
A1  - Smith, A. J.
A1  - Springer, R. W.
A1  - Surajbali, P.
A1  - Taboada, Ignacio
A1  - Tibolla, O.
A1  - Tollefson, K.
A1  - Torres, I.
A1  - Ukwatta, Tilan N.
A1  - Villasenor, L.
A1  - Weisgarber, T.
A1  - Westerhoff, Stefan
A1  - Wisher, I. G.
A1  - Wood, J.
A1  - Yapici, Tolga
A1  - Yodh, G.
A1  - Zepeda, A.
A1  - Zhou, H.
T1  - VERITAS and Fermi-LAT Observations of TeV Gamma-Ray Sources Discovered by HAWC in the 2HWC Catalog
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - The High Altitude Water Cherenkov (HAWC) collaboration recently published their 2HWC catalog, listing 39 very high energy (VHE; >100 GeV) gamma-ray sources based on 507 days of observation. Among these, 19 sources are not associated with previously known teraelectronvolt (TeV) gamma-ray sources. We have studied 14 of these sources without known counterparts with VERITAS and Fermi-LAT. VERITAS detected weak gamma-ray emission in the 1 TeV-30 TeV band in the region of DA 495, a pulsar wind nebula coinciding with 2HWC J1953+294, confirming the discovery of the source by HAWC. We did not find any counterpart for the selected 14 new HAWC sources from our analysis of Fermi-LAT data for energies higher than 10 GeV. During the search, we detected gigaelectronvolt (GeV) gamma-ray emission coincident with a known TeV pulsar wind nebula, SNR G54.1+0.3 (VER J1930+188), and a 2HWC source, 2HWC J1930+188. The fluxes for isolated, steady sources in the 2HWC catalog are generally in good agreement with those measured by imaging atmospheric Cherenkov telescopes. However, the VERITAS fluxes for SNR G54.1+0.3, DA 495, and TeV J2032+4130 are lower than those measured by HAWC, and several new HAWC sources are not detected by VERITAS. This is likely due to a change in spectral shape, source extension, or the influence of diffuse emission in the source region.
KW  - gamma rays: general
Y1  - 2018
U6  - https://doi.org/10.3847/1538-4357/aade4e
SN  - 0004-637X
SN  - 1538-4357
VL  - 866
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Bugaev, V.
A1  - Connolly, M. P.
A1  - Cui, Wei
A1  - Errando, Manel
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, John P.
A1  - Flinders, A.
A1  - Fortson, L.
A1  - Furniss, Amy
A1  - Gillanders, Gerard H.
A1  - Huetten, M.
A1  - Hanna, David
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, Caitlin A.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, David
A1  - Krause, Maria
A1  - Krennrich, F.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - Maier, Gernot
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Ong, R. A.
A1  - Park, N.
A1  - Perkins, Jeremy S.
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Popkow, Alexis
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weiner, O. M.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, David A.
A1  - Zitzer, B.
A1  - Vurm, Indrek
A1  - Beloborodov, Andrei
T1  - A Strong Limit on the Very-high-energy Emission from GRB 150323A
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - 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.
KW  - gamma rays: general
KW  - gamma-ray burst: general
KW  - gamma-ray burst: individual (GRB 150323A)
Y1  - 2018
U6  - https://doi.org/10.3847/1538-4357/aab371
SN  - 0004-637X
SN  - 1538-4357
VL  - 857
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brantseg, T.
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Connolly, M. P.
A1  - Cui, Wei
A1  - Daniel, M. K.
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, John P.
A1  - Fortson, L.
A1  - Furniss, Amy
A1  - Gillanders, Gerard H.
A1  - Gunawardhana, Isuru
A1  - Huetten, M.
A1  - Hanna, David
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, Caitlin A.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kertzman, M.
A1  - Krennrich, F.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Ong, R. A.
A1  - Otte, Adam Nepomuk
A1  - Park, N.
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Williams, D. A.
A1  - Zitzer, B.
A1  - Jorstad, Svetlana G.
A1  - Marscher, Alan P.
A1  - Lister, Matthew L.
A1  - Kovalev, Yuri Y.
A1  - Pushkarev, A. B.
A1  - Savolainen, Tuomas
A1  - Agudo, I.
A1  - Molina, S. N.
A1  - Gomez, J. L.
A1  - Larionov, Valeri M.
A1  - Borman, G. A.
A1  - Mokrushina, A. A.
A1  - Tornikoski, Merja
A1  - Lahteenmaki, A.
A1  - Chamani, W.
A1  - Enestam, S.
A1  - Kiehlmann, S.
A1  - Hovatta, Talvikki
A1  - Smith, P. S.
A1  - Pontrelli, P.
T1  - Multiwavelength Observations of the Blazar BL Lacertae
BT  - a new Fast TeV Gamma-Ray Flare
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - Combined with measurements made by very-long-baseline interferometry, the observations of fast TeV gamma-ray flares probe the structure and emission mechanism of blazar jets. However, only a handful of such flares have been detected to date, and only within the last few years have these flares been observed from lower-frequency-peaked BL. Lac objects and flat-spectrum radio quasars. We report on a fast TeV gamma-ray flare from the blazar BL. Lacertae observed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS). with a rise time of similar to 2.3 hr and a decay time of similar to 36 min. The peak flux above 200 GeV is (4.2 +/- 0.6) x 10(-6) photon m(-2) s(-1) measured with a 4-minute-binned light curve, corresponding to similar to 180% of the flux that is observed from the Crab Nebula above the same energy threshold. Variability contemporaneous with the TeV gamma-ray flare was observed in GeV gamma-ray, X-ray, and optical flux, as well as in optical and radio polarization. Additionally, a possible moving emission feature with superluminal apparent velocity was identified in Very Long Baseline Array observations at 43 GHz, potentially passing the radio core of the jet around the time of the gamma-ray flare. We discuss the constraints on the size, Lorentz factor, and location of the emitting region of the flare, and the interpretations with several theoretical models that invoke relativistic plasma passing stationary shocks.
KW  - BL Lacertae objects: individual (BL Lacertae = VER J2202+422)
KW  - galaxies: active
Y1  - 2018
U6  - https://doi.org/10.3847/1538-4357/aab35c
SN  - 0004-637X
SN  - 1538-4357
VL  - 856
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  -