TY - JOUR A1 - Archambault, S. A1 - Archer, A. A1 - Benbow, W. A1 - Buchovecky, M. A1 - Bugaev, V. A1 - Cerruti, M. A1 - Connolly, M. P. A1 - Cui, W. A1 - Falcone, A. A1 - Alonso, M. Fernandez A1 - Finley, J. P. A1 - Fleischhack, H. A1 - Fortson, L. A1 - Furniss, A. A1 - Griffin, S. A1 - Hutten, M. A1 - Hervet, O. A1 - Holder, J. A1 - Humensky, T. B. A1 - Johnson, C. A. A1 - Kaaret, P. A1 - Kar, P. A1 - Kieda, D. A1 - Krause, M. A1 - Krennrich, F. A1 - Lang, M. J. A1 - Lin, T. T. Y. A1 - Maier, G. A1 - McArthur, S. A1 - Moriarty, P. A1 - Nieto, D. A1 - Ong, R. A. A1 - Otte, A. N. A1 - Pohl, M. A1 - Popkow, A. A1 - Pueschel, Elisa A1 - Quinn, J. A1 - Ragan, K. A1 - Reynolds, P. T. A1 - Richards, G. T. A1 - Roache, E. A1 - Rovero, A. C. A1 - Sadeh, I. A1 - Shahinyan, K. A1 - Staszak, D. A1 - Telezhinsky, Igor O. A1 - Tyler, J. A1 - Wakely, S. P. A1 - Weinstein, A. A1 - Weisgarber, T. A1 - Wilcox, P. A1 - Wilhelm, Alina A1 - Williams, D. A. A1 - Zitzer, B. T1 - Search for Magnetically Broadened Cascade Emission from Blazars with VERITAS JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - 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. KW - BL Lacertae objects: general KW - galaxies: active KW - gamma rays: galaxies KW - magnetic fields Y1 - 2017 U6 - https://doi.org/10.3847/1538-4357/835/2/288 SN - 0004-637X SN - 1538-4357 VL - 835 IS - 2 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Archambault, S. A1 - Archer, A. A1 - Benbow, Wystan A1 - Bird, Ralph A1 - Bourbeau, E. A1 - Buchovecky, M. A1 - Buckley, J. H. A1 - Bugaev, V. A1 - Cerruti, M. A1 - Connolly, M. P. A1 - Cui, W. A1 - Dwarkadas, Vikram V. A1 - Errando, M. A1 - Falcone, A. A1 - Feng, Q. A1 - Finley, J. P. A1 - Fleischhack, H. A1 - Fortson, L. A1 - Furniss, A. A1 - Griffin, S. A1 - Huetten, M. A1 - Hanna, D. A1 - Holder, J. A1 - Johnson, C. A. A1 - Kaaret, P. A1 - Kar, P. A1 - Kelley-Hoskins, N. A1 - Kertzman, M. A1 - Kieda, D. A1 - Krause, M. A1 - Kumar, S. A1 - Lang, M. J. A1 - Maier, G. A1 - McArthur, S. A1 - McCann, A. A1 - Moriarty, P. A1 - Mukherjee, R. A1 - Nieto, D. A1 - Ong, R. A. A1 - Otte, A. N. A1 - Park, Nahee 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 - Sadeh, I. A1 - Santander, M. A1 - Sembroski, G. H. A1 - Shahinyan, K. A1 - Slane, P. A1 - Staszak, D. A1 - Telezhinsky, Igor O. A1 - Trepanier, S. A1 - Tyler, J. A1 - Wakely, S. P. A1 - Weinstein, A. A1 - Weisgarber, T. A1 - Wilcox, P. A1 - Wilhelm, Alina A1 - Williams, D. A. A1 - Zitzer, B. T1 - Gamma-ray Observations of Tycho's Supernova Remnant with VERITAS and Fermi JF - The astrophysical journal : an international review of spectroscopy and astronomical physics KW - material KW - data behind figure Y1 - 2017 U6 - https://doi.org/10.3847/1538-4357/836/1/23 SN - 0004-637X SN - 1538-4357 VL - 836 IS - 1 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 - Archambault, S. A1 - Archer, A. A1 - Benbow, W. A1 - Bird, R. A1 - Bourbeau, E. A1 - Brantseg, T. A1 - Buchovecky, M. A1 - Buckley, J. H. A1 - Bugaev, V. A1 - Byrum, K. A1 - Cerruti, M. A1 - Christiansen, J. L. A1 - Connolly, M. P. A1 - Cui, W. A1 - Daniel, M. K. A1 - Feng, Q. A1 - Finley, J. P. A1 - Fleischhack, H. A1 - Fortson, L. A1 - Furniss, A. A1 - Geringer-Sameth, A. A1 - Griffin, S. A1 - Grube, J. A1 - Hütten, M. A1 - Hakansson, N. A1 - Hanna, D. A1 - Hervet, O. A1 - Holder, J. A1 - Hughes, G. A1 - Hummensky, B. A1 - Johnson, C. A. A1 - Kaaret, P. A1 - Kar, P. A1 - Kelley-Hoskins, N. A1 - Kertzman, M. A1 - Kieda, D. A1 - Koushiappas, S. A1 - Krause, M. A1 - Krennrich, F. A1 - Lang, M. J. A1 - Lin, T. T. Y. A1 - McArthur, S. A1 - Moriarty, P. A1 - Mukherjee, R. A1 - Nieto, D. A1 - Ong, R. A. A1 - Otte, A. N. A1 - Park, N. A1 - Pohl, M. 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 - Smith, A. W. A1 - Staszak, D. A1 - Telezhinsky, Igor O. A1 - Trepanier, S. A1 - Tucci, J. V. A1 - Tyler, J. A1 - Wakely, S. P. A1 - Weinstein, A. A1 - Wilcox, P. A1 - Williams, D. A. A1 - Zitzer, B. T1 - Dark matter constraints from a joint analysis of dwarf Spheroidal galaxy observations with VERITAS JF - Physical review : D, Particles, fields, gravitation, and cosmology N2 - We present constraints on the annihilation cross section of weakly interacting massive particles dark matter based on the joint statistical analysis of four dwarf galaxies with VERITAS. These results are derived from an optimized photon weighting statistical technique that improves on standard imaging atmospheric Cherenkov telescope (IACT) analyses by utilizing the spectral and spatial properties of individual photon events. We report on the results of similar to 230 hours of observations of five dwarf galaxies and the joint statistical analysis of four of the dwarf galaxies. We find no evidence of gamma-ray emission from any individual dwarf nor in the joint analysis. The derived upper limit on the dark matter annihilation cross section from the joint analysis is 1.35 x 10(-23) cm(3) s(-1) at 1 TeV for the bottom quark (b (b) over bar) final state, 2.85 x 10(-24) cm(3) s(-1) at 1 TeV for the tau lepton (tau+tau(-)) final state and 1.32 x 10-25 cm(3) s(-1) at 1 TeV for the gauge boson (gamma gamma) final state. Y1 - 2017 U6 - https://doi.org/10.1103/PhysRevD.95.082001 SN - 2470-0010 SN - 2470-0029 VL - 95 IS - 8 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Archambault, S. A1 - Archer, A. A1 - Benbow, W. A1 - Bird, Ralph A1 - Bourbeau, E. A1 - Bouvier, A. A1 - Buchovecky, M. A1 - Bugaev, V. A1 - Cardenzana, J. V. A1 - Cerruti, M. A1 - Ciupik, L. A1 - Connolly, M. P. A1 - Cui, W. A1 - Daniel, M. K. 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 - Hanna, D. A1 - Hervet, O. A1 - Holder, J. A1 - Hughes, G. A1 - Humensky, T. B. A1 - Hutten, M. A1 - Johnson, C. A. A1 - Kaaret, P. A1 - Kar, P. A1 - Kertzman, M. A1 - Kieda, D. A1 - Krause, M. A1 - Lang, M. J. A1 - Lin, T. T. Y. 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 - 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 - Sembroski, G. H. A1 - Shahinyan, K. A1 - Staszak, D. A1 - Telezhinsky, Igor O. A1 - Trepanier, S. A1 - Wakely, S. P. A1 - Weinstein, A. A1 - Wilcox, P. A1 - Williams, D. A. A1 - Zitzer, B. T1 - Gamma-ray observations under bright moonlight with VERITAS JF - Astroparticle physics N2 - 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. KW - Instrumentation KW - Moonlight KW - Observing methods KW - VERITAS KW - IACT Y1 - 2017 U6 - https://doi.org/10.1016/j.astropartphys.2017.03.001 SN - 0927-6505 SN - 1873-2852 VL - 91 SP - 34 EP - 43 PB - Elsevier CY - Amsterdam 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 - 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 - 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 - Archer, A. A1 - Benbow, Wystan A1 - Bird, Ralph A1 - Brose, Robert A1 - Buchovecky, M. A1 - Bugaev, V A1 - Cui, Wei A1 - Danie, M. K. A1 - Falcone, A. A1 - Feng, Qi A1 - Finley, John P. A1 - Flinders, A. A1 - Fortson, L. A1 - Furniss, Amy A1 - Gillanders, Gerard H. A1 - Huttens, 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 - Kieda, David A1 - Krause, Maria 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 - Nieto, Daniel A1 - Ong, R. A. A1 - Otte, A. N. A1 - Park, Nahee A1 - Petrashyk, A. A1 - Pohl, Martin A1 - Popkow, Alexis A1 - Pueschel, Elisa A1 - Quinn, J. A1 - Ragan, K. A1 - Reynold, P. T. A1 - Richards, Gregory T. A1 - Roache, E. A1 - Rulten, C. A1 - Sadeh, I 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 - Brisken, W. F. A1 - Pontrelli, P. T1 - HESS J1943+213 BT - An extreme blazar shining through the galactic plane JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - HESS J1943+213 is a very high energy (VHE; > 100 GeV) gamma-ray source in the direction of the Galactic plane. Studies exploring the classification of the source are converging toward its identification as an extreme synchrotron BL Lac object. Here we present 38 hr of VERITAS observations of HESS J1943+213 taken over 2 yr. The source is detected with a significance of similar to 20 standard deviations, showing a remarkably stable flux and spectrum in VHE gamma-rays. Multifrequency Very Long Baseline Array (VLBA) observations of the source confirm the extended, jet-like structure previously found in the 1.6 GHz band with the European VLBI Network and detect this component in the 4.6 and 7.3 GHz bands. The radio spectral indices of the core and the jet and the level of polarization derived from the VLBA observations are in a range typical for blazars. Data from VERITAS, Fermi-LAT, Swift-XRT, the FLWO 48 ' telescope, and archival infrared and hard X-ray observations are used to construct and model the spectral energy distribution (SED) of the source with a synchrotron self-Compton model. The well-measured gamma-ray peak of the SED with VERITAS and Fermi-LAT provides constraining upper limits on the source redshift. Possible contribution of secondary gamma-rays from ultra-high-energy cosmic-ray-initiated electromagnetic cascades to the gamma-ray emission is explored, finding that only a segment of the VHE spectrum can be accommodated with this process. A variability search is performed across X-ray and gamma-ray bands. No statistically significant flux or spectral variability is detected. KW - astroparticle physics KW - BL Lacertae objects: individual (HESS J1943+213, VER J1943+213) KW - galaxies: active KW - galaxies: jets KW - galaxies: nuclei KW - gamma rays: galaxies Y1 - 2018 U6 - https://doi.org/10.3847/1538-4357/aacbd0 SN - 0004-637X SN - 1538-4357 VL - 862 IS - 1 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Archer, A. A1 - Benbow, W. A1 - Bird, R. A1 - Brose, Robert A1 - Buchovecky, M. A1 - Bugaev, V. A1 - Connolly, M. P. A1 - Cui, W. A1 - Daniel, M. K. A1 - Falcone, A. A1 - Feng, Q. A1 - Finley, J. P. A1 - Fleischhack, H. A1 - Fortson, L. A1 - Furniss, A. A1 - Hanna, D. A1 - Hervet, O. A1 - Holder, J. A1 - Hughes, G. A1 - Humensky, T. B. A1 - Hutten, M. A1 - Johnson, C. A. A1 - Kaaret, P. A1 - Kelley-Hoskins, N. 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 - Tyler, J. A1 - Wakely, S. P. A1 - Weiner, O. M. A1 - Wilcox, P. A1 - Wilhelm, Alina A1 - Williams, D. A. A1 - Wissel, S. A. A1 - Zitzer, B. T1 - Measurement of the iron spectrum in cosmic rays by VERITAS JF - Physical review : D, Particles, fields, gravitation, and cosmology N2 - 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. Y1 - 2018 U6 - https://doi.org/10.1103/PhysRevD.98.022009 SN - 2470-0010 SN - 2470-0029 VL - 98 IS - 2 PB - American Physical Society CY - College Park ER -