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  - Benbow, W.
A1  - Bird, R.
A1  - Brill, A.
A1  - Brose, Robert
A1  - Chromey, A. J.
A1  - Daniel, M. K.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Gillanders, G. H.
A1  - Giuri, C.
A1  - Gueta, O.
A1  - Hanna, D.
A1  - Halpern, J. P.
A1  - Hassan, Tarek
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Joyce, Amy M.
A1  - Kaaret, P.
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Krause, M.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - Maier, Gernot
A1  - Matthews, N.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Nieto, D.
A1  - Nievas-Rosillos, M.
A1  - Ong, R. A.
A1  - Park, N.
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Pueschel, Elisa
A1  - Quinn, John
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, Iftach
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, K.
A1  - Sushch, Iurii
A1  - Wakely, S. P.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, David A.
A1  - Williamson, T. J.
T1  - Direct measurement of stellar angular diameters by the VERITAS Cherenkov telescopes
JF  - Nature astronomy
N2  - The angular size of a star is a critical factor in determining its basic properties1. Direct measurement of stellar angular diameters is difficult: at interstellar distances stars are generally too small to resolve by any individual imaging telescope. This fundamental limitation can be overcome by studying the diffraction pattern in the shadow cast when an asteroid occults a star2, but only when the photometric uncertainty is smaller than the noise added by atmospheric scintillation3. Atmospheric Cherenkov telescopes used for particle astrophysics observations have not generally been exploited for optical astronomy due to the modest optical quality of the mirror surface. However, their large mirror area makes them well suited for such high-time-resolution precision photometry measurements4. Here we report two occultations of stars observed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS)5 Cherenkov telescopes with millisecond sampling, from which we are able to provide a direct measurement of the occulted stars’ angular diameter at the ≤0.1 mas scale. This is a resolution never achieved before with optical measurements and represents an order of magnitude improvement over the equivalent lunar occultation method6. We compare the resulting stellar radius with empirically derived estimates from temperature and brightness measurements, confirming the latter can be biased for stars with ambiguous stellar classifications.
Y1  - 2019
U6  - https://doi.org/10.1038/s41550-019-0741-z
SN  - 2397-3366
VL  - 3
IS  - 6
SP  - 511
EP  - 516
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Chromey, A. J.
A1  - Cui, Wei
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, J. P.
A1  - Fortson, Lucy
A1  - Furniss, Amy
A1  - Gent, A.
A1  - Gueta, O.
A1  - Hanna, David
A1  - Hassan, T.
A1  - Hervet, Olivier
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  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - McCann, A.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Ong, R. A.
A1  - Otte, Adam Nepomuk
A1  - Pandel, D.
A1  - Park, N.
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Sadeh, I
A1  - Santander, Marcos
A1  - Scott, S. S.
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Sushch, Iurii
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.
T1  - A Search for Pulsed Very High-energy Gamma-Rays from 13 Young Pulsars in Archival VERITAS Data
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - 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.
KW  - gamma rays: general
KW  - pulsars: general
KW  - stars: neutron
Y1  - 2019
U6  - https://doi.org/10.3847/1538-4357/ab14f4
SN  - 0004-637X
SN  - 1538-4357
VL  - 876
IS  - 2
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  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Connolly, M. P.
A1  - Cui, W.
A1  - Daniel, M. K.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Gillanders, G.
A1  - Huetten, M.
A1  - Hanna, D.
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
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  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Petrashyk, A.
A1  - Pohl, M.
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  - Staszak, D.
A1  - Sushch, I.
A1  - Wakely, S. P.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Williamson, T. J.
A1  - Zitzer, B.
T1  - Measurement of cosmic-ray electrons at TeV energies by VERITAS
JF  - Physical review : D, Particles, fields, gravitation, and cosmology
N2  - Cosmic-ray electrons and positrons (CREs) at GeV-TeV energies are a unique probe of our local Galactic neighborhood. CREs lose energy rapidly via synchrotron radiation and inverse-Compton scattering processes while propagating within the Galaxy, and these losses limit their propagation distance. For electrons with TeV energies, the limit is on the order of a kiloparsec. Within that distance, there are only a few known astrophysical objects capable of accelerating electrons to such high energies. It is also possible that the CREs are the products of the annihilation or decay of heavy dark matter (DM) particles. VERITAS, an array of imaging air Cherenkov telescopes in southern Arizona, is primarily utilized for gamma-ray astronomy but also simultaneously collects CREs during all observations. We describe our methods of identifying CREs in VERITAS data and present an energy spectrum, extending from 300 GeV to 5 TeV, obtained from approximately 300 hours of observations. A single power-law fit is ruled out in VERITAS data. We find that the spectrum of CREs is consistent with a broken power law, with a break energy at 710 +/- 40(stat) +/- 140(syst) GeV.
Y1  - 2018
U6  - https://doi.org/10.1103/PhysRevD.98.062004
SN  - 2470-0010
SN  - 2470-0029
VL  - 98
IS  - 6
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Ahnen, M. L.
A1  - Ansoldi, S.
A1  - Antonelli, L. A.
A1  - Arcaro, C.
A1  - Babic, A.
A1  - Banerjee, B.
A1  - Bangale, P.
A1  - Barres de Almeida, U.
A1  - Barrio, J. A.
A1  - Gonzalez, J. Becerra
A1  - Bednarek, W.
A1  - Bernardini, E.
A1  - Berti, A.
A1  - Bhattacharyya, W.
A1  - Blanch, O.
A1  - Bonnoli, G.
A1  - Carosi, R.
A1  - Carosi, A.
A1  - Chatterjee, A.
A1  - Colak, S. M.
A1  - Colin, P.
A1  - Colombo, E.
A1  - Contreras, J. L.
A1  - Cortina, J.
A1  - Covino, S.
A1  - Cumani, P.
A1  - Da Vela, P.
A1  - Dazzi, F.
A1  - De Angelis, A.
A1  - De Lotto, B.
A1  - Delfino, M.
A1  - Delgado, Jose Miguel Martins
A1  - Di Pierro, F.
A1  - Doert, M.
A1  - Dominguez, A.
A1  - Prester, D. Dominis
A1  - Doro, M.
A1  - Glawion, D. Eisenacher
A1  - Engelkemeier, M.
A1  - Ramazani, V. Fallah
A1  - Fernandez-Barral, A.
A1  - Fidalgo, D.
A1  - Fonseca, M. V.
A1  - Font, L.
A1  - Fruck, C.
A1  - Galindo, D.
A1  - Lopez, R. J. Garcia
A1  - Garczarczyk, M.
A1  - Gaug, M.
A1  - Giammaria, P.
A1  - Godinovic, N.
A1  - Gora, D.
A1  - Guberman, D.
A1  - Hadasch, D.
A1  - Hahn, A.
A1  - Hassan, T.
A1  - Hayashida, M.
A1  - Herrera, J.
A1  - Hose, J.
A1  - Hrupec, D.
A1  - Ishio, K.
A1  - Konno, Y.
A1  - Kubo, H.
A1  - Kushida, J.
A1  - Kuvezdic, D.
A1  - Lelas, D.
A1  - Lindfors, E.
A1  - Lombardi, S.
A1  - Longo, F.
A1  - Lopez, M.
A1  - Maggio, C.
A1  - Majumdar, P.
A1  - Makariev, M.
A1  - Maneva, G.
A1  - Manganaro, M.
A1  - Maraschi, L.
A1  - Mariotti, M.
A1  - Martinez, M.
A1  - Mazin, D.
A1  - Menzel, U.
A1  - Minev, M.
A1  - Miranda, J. M.
A1  - Mirzoyan, R.
A1  - Moralejo, A.
A1  - Moreno, V.
A1  - Moretti, E.
A1  - Nagayoshi, T.
A1  - Neustroev, V.
A1  - Niedzwiecki, A.
A1  - Nievas Rosillo, M.
A1  - Nigro, C.
A1  - Nilsson, K.
A1  - Ninci, D.
A1  - Nishijima, K.
A1  - Noda, K.
A1  - Nogues, L.
A1  - Paiano, S.
A1  - Palacio, J.
A1  - Paneque, D.
A1  - Paoletti, R.
A1  - Paredes, J. M.
A1  - Pedaletti, G.
A1  - Peresano, M.
A1  - Perri, L.
A1  - Persic, M.
A1  - Moroni, P. G. Prada
A1  - Prandini, E.
A1  - Puljak, I.
A1  - Garcia, J. R.
A1  - Reichardt, I.
A1  - Ribo, M.
A1  - Rico, J.
A1  - Righi, C.
A1  - Rugliancich, A.
A1  - Saito, T.
A1  - Satalecka, K.
A1  - Schroeder, S.
A1  - Schweizer, T.
A1  - Shore, S. N.
A1  - Sitarek, J.
A1  - Snidaric, I.
A1  - Sobczynska, D.
A1  - Stamerra, A.
A1  - Strzys, M.
A1  - Suric, T.
A1  - Takalo, L.
A1  - Tavecchio, F.
A1  - Temnikov, P.
A1  - Terzic, T.
A1  - Teshima, M.
A1  - Torres-Alba, N.
A1  - Treves, A.
A1  - Tsujimoto, S.
A1  - Vanzo, G.
A1  - Vazquez Acosta, M.
A1  - Vovk, I.
A1  - Ward, J. E.
A1  - Will, M.
A1  - Zaric, D.
A1  - Arbet-Engels, A.
A1  - Baack, D.
A1  - Balbo, M.
A1  - Biland, A.
A1  - Blank, M.
A1  - Bretz, T.
A1  - Bruegge, K.
A1  - Bulinski, M.
A1  - Buss, J.
A1  - Dmytriiev, A.
A1  - Dorner, D.
A1  - Einecke, S.
A1  - Elsaesser, D.
A1  - Herbst, T.
A1  - Hildebrand, D.
A1  - Kortmann, L.
A1  - Linhoff, L.
A1  - Mahlke, M.
A1  - Mannheim, K.
A1  - Mueller, S. A.
A1  - Neise, D.
A1  - Neronov, A.
A1  - Noethe, M.
A1  - Oberkirch, J.
A1  - Paravac, A.
A1  - Rhode, W.
A1  - Schleicher, B.
A1  - Schulz, F.
A1  - Sedlaczek, K.
A1  - Shukla, A.
A1  - Sliusar, V.
A1  - Walter, R.
A1  - Archer, A.
A1  - Benbow, W.
A1  - Bird, R.
A1  - Brose, Robert
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Christiansen, J. L.
A1  - Cui, W.
A1  - Daniel, M. K.
A1  - Falcone, A.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Gillanders, G. H.
A1  - Gueta, O.
A1  - Hanna, D.
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Huetten, M.
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  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Petrashyk, A.
A1  - Pichel, A.
A1  - Pohl, Martin
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Rovero, A. C.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, K.
A1  - Sushch, Iurii
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhel, A.
A1  - Williams, D. A.
A1  - Williamson, T. J.
A1  - Zitzer, B.
A1  - Perri, M.
A1  - Verrecchia, F.
A1  - Leto, C.
A1  - Villata, M.
A1  - Raiteri, C. M.
A1  - Jorstad, S. G.
A1  - Larionov, V. M.
A1  - Blinov, D. A.
A1  - Grishina, T. S.
A1  - Kopatskaya, E. N.
A1  - Larionova, E. G.
A1  - Nikiforova, A. A.
A1  - Morozova, D. A.
A1  - Troitskaya, Yu. V.
A1  - Troitsky, I. S.
A1  - Kurtanidze, O. M.
A1  - Nikolashvili, M. G.
A1  - Kurtanidze, S. O.
A1  - Kimeridze, G. N.
A1  - Chigladze, R. A.
A1  - Strigachev, A.
A1  - Sadun, A. C.
T1  - Extreme HBL behavior of Markarian 501 during 2012
JF  - Astronomy and astrophysics : an international weekly journal / European Southern Observatory (ESO)
N2  - Aims. We aim to characterize the multiwavelength emission from Markarian 501 (Mrk 501), quantify the energy-dependent variability, study the potential multiband correlations, and describe the temporal evolution of the broadband emission within leptonic theoretical scenarios. Methods. We organized a multiwavelength campaign to take place between March and July of 2012. Excellent temporal coverage was obtained with more than 25 instruments, including the MAGIC, FACT and VERITAS Cherenkov telescopes, the instruments on board the Swift and Fermi spacecraft, and the telescopes operated by the GASP-WEBT collaboration. Results. Mrk 501 showed a very high energy (VHE) gamma-ray flux above 0.2 TeV of similar to 0.5 times the Crab Nebula flux (CU) for most of the campaign. The highest activity occurred on 2012 June 9, when the VHE flux was similar to 3 CU, and the peak of the high-energy spectral component was found to be at similar to 2 TeV. Both the X-ray and VHE gamma-ray spectral slopes were measured to be extremely hard, with spectral indices <2 during most of the observing campaign, regardless of the X-ray and VHE flux. This study reports the hardest Mrk 501 VHE spectra measured to date. The fractional variability was found to increase with energy, with the highest variability occurring at VHE. Using the complete data set, we found correlation between the X-ray and VHE bands; however, if the June 9 flare is excluded, the correlation disappears (significance <3 sigma) despite the existence of substantial variability in the X-ray and VHE bands throughout the campaign. Conclusions. The unprecedentedly hard X-ray and VHE spectra measured imply that their low- and high-energy components peaked above 5 keV and 0.5 TeV, respectively, during a large fraction of the observing campaign, and hence that Mrk 501 behaved like an extreme high-frequency-peaked blazar (EHBL) throughout the 2012 observing season. This suggests that being an EHBL may not be a permanent characteristic of a blazar, but rather a state which may change over time. The data set acquired shows that the broadband spectral energy distribution (SED) of Mrk 501, and its transient evolution, is very complex, requiring, within the framework of synchrotron self-Compton (SSC) models, various emission regions for a satisfactory description. Nevertheless the one-zone SSC scenario can successfully describe the segments of the SED where most energy is emitted, with a significant correlation between the electron energy density and the VHE gamma-ray activity, suggesting that most of the variability may be explained by the injection of high-energy electrons. The one-zone SSC scenario used reproduces the behavior seen between the measured X-ray and VHE gamma-ray fluxes, and predicts that the correlation becomes stronger with increasing energy of the X-rays.
KW  - astroparticle physics
KW  - acceleration of particles
KW  - radiation mechanisms: non-thermal
KW  - BL Lacertae objects: general
KW  - BL Lacertae objects: individual: Mrk501
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201833704
SN  - 1432-0746
VL  - 620
PB  - EDP Sciences
CY  - Les Ulis
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  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brill, A.
A1  - Brose, Robert
A1  - Buckley, J. H.
A1  - Chromey, A. J.
A1  - Daniel, M. K.
A1  - Falcone, A.
A1  - Finley, J. P.
A1  - Fortson, L.
A1  - Furniss, Amy
A1  - Gent, A.
A1  - Gillanders, Gerald H.
A1  - Hanna, David
A1  - Hassan, T.
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kertzman, M.
A1  - Kieda, David
A1  - Krause, Maria
A1  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - Maier, Gernot
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  - Richards, Gregory T.
A1  - Roache, E.
A1  - Sadeh, I.
A1  - Santander, Marcos
A1  - Schlenstedt, S.
A1  - Sembroski, G. H.
A1  - Sushch, Iurii
A1  - Tyler, J.
A1  - Vassiliev, V. V.
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, David A.
A1  - Williamson, T. J.
A1  - Zitzer, B.
A1  - Acciari, V. A.
A1  - Ansoldi, S.
A1  - Antonelli, L. A.
A1  - Engels, A. Arbet
A1  - Baack, D.
A1  - Babic, A.
A1  - Banerjee, B.
A1  - de Almeida, U. Barres
A1  - Barrio, J. A.
A1  - Becerra Gonzalez, Josefa
A1  - Bednarek, Wlodek
A1  - Bernardini, Elisa
A1  - Berti, A.
A1  - Besenrieder, J.
A1  - Bhattacharyya, W.
A1  - Bigongiari, C.
A1  - Biland, A.
A1  - Blanch, O.
A1  - Bonnoli, G.
A1  - Busetto, G.
A1  - Carosi, R.
A1  - Ceribella, G.
A1  - Cikota, S.
A1  - Colak, S. M.
A1  - Colin, P.
A1  - Colombo, E.
A1  - Contreras, J. L.
A1  - Cortina, J.
A1  - Covino, S.
A1  - Da Vela, P.
A1  - Dazzi, F.
A1  - De Angelis, A.
A1  - De Lotto, B.
A1  - Delfino, M.
A1  - Delgado, J.
A1  - Di Pierro, F.
A1  - Do Souto Espinera, E.
A1  - Dominguez, A.
A1  - Prester, D. Dominis
A1  - Dorner, D.
A1  - Doro, M.
A1  - Einecke, S.
A1  - Elsaesser, D.
A1  - Ramazani, V. Fallah
A1  - Fattorini, A.
A1  - Fernandez-Barral, A.
A1  - Ferrara, G.
A1  - Fidalgo, D.
A1  - Foffano, L.
A1  - Fonseca, M. V.
A1  - Font, L.
A1  - Fruck, C.
A1  - Galindo, D.
A1  - Gallozzi, S.
A1  - Lopez, R. J. Garcia
A1  - Garczarczyk, M.
A1  - Gasparyan, S.
A1  - Gaug, Markus
A1  - Giammaria, P.
A1  - Godinovic, N.
A1  - Guberman, D.
A1  - Hadasch, D.
A1  - Hahn, A.
A1  - Herrera, J.
A1  - Hoang, J.
A1  - Hrupec, D.
A1  - Inoue, S.
A1  - Ishio, K.
A1  - Iwamura, Y.
A1  - Kubo, H.
A1  - Kushida, J.
A1  - Kuvezdic, D.
A1  - Lamastra, A.
A1  - Lelas, D.
A1  - Leone, Francesco
A1  - Lindfors, E.
A1  - Lombardi, S.
A1  - Longo, Francesco
A1  - Lopez, M.
A1  - Lopez-Oramas, A.
A1  - Machado de Oliveira Fraga, B.
A1  - Maggio, C.
A1  - Majumdar, P.
A1  - Makariev, M.
A1  - Mallamaci, M.
A1  - Maneva, G.
A1  - Manganaro, M.
A1  - Mannheim, K.
A1  - Maraschi, L.
A1  - Mariotti, M.
A1  - Martinez, M.
A1  - Masuda, S.
A1  - Mazin, D.
A1  - Minev, M.
A1  - Miranda, J. M.
A1  - Mirzoyan, R.
A1  - Molina, E.
A1  - Moralejo, A.
A1  - Moreno, V.
A1  - Moretti, E.
A1  - Munar-Adrover, Pere
A1  - Neustroev, V.
A1  - Niedzwiecki, Andrzej
A1  - Rosillo, Mireia Nievas
A1  - Nigro, C.
A1  - Nilsson, Kari
A1  - Ninci, D.
A1  - Nishijima, K.
A1  - Noda, K.
A1  - Nogues, L.
A1  - Noethe, M.
A1  - Paiano, Simona
A1  - Palacio, J.
A1  - Paneque, D.
A1  - Paoletti, R.
A1  - Paredes, J. M.
A1  - Pedaletti, G.
A1  - Penil, P.
A1  - Peresano, M.
A1  - Persic, M.
A1  - Moroni, P. G. Prada
A1  - Prandini, E.
A1  - Puljak, I.
A1  - Garcia, J. R.
A1  - Rhode, W.
A1  - Ribo, Marc
A1  - Rico, J.
A1  - Righi, C.
A1  - Rugliancich, A.
A1  - Saha, Lab
A1  - Sahakyan, Narek
A1  - Saito, T.
A1  - Satalecka, K.
A1  - Schweizer, T.
A1  - Sitarek, J.
A1  - Snidaric, I.
A1  - Sobczynska, D.
A1  - Somero, A.
A1  - Stamerra, A.
A1  - Strzys, M.
A1  - Suric, T.
A1  - Tavecchio, Fabrizio
A1  - Temnikov, P.
A1  - Terzic, T.
A1  - Teshima, M.
A1  - Torres-Alba, N.
A1  - Tsujimoto, S.
A1  - van Scherpenberg, J.
A1  - Vanzo, G.
A1  - Vazquez Acosta, M.
A1  - Vovk, I.
A1  - Will, M.
A1  - Zaric, D.
T1  - Periastron Observations of TeV Gamma-Ray Emission from a Binary System with a 50-year Period
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters
N2  - We report on observations of the pulsar/Be star binary system PSR J2032+4127/MT91 213 in the energy range between 100 GeV and 20 TeV with the Very Energetic Radiation Imaging Telescope Array and Major Atmospheric Gamma Imaging Cherenkov telescope arrays. The binary orbit has a period of approximately 50 years, with the most recent periastron occurring on 2017 November 13. Our observations span from 18 months prior to periastron to one month after. A new point-like gamma-ray source is detected, coincident with the location of PSR J2032+4127/MT91 213. The gamma-ray light curve and spectrum are well characterized over the periastron passage. The flux is variable over at least an order of magnitude, peaking at periastron, thus providing a firm association of the TeV source with the pulsar/Be star system. Observations prior to periastron show a cutoff in the spectrum at an energy around 0.5 TeV. This result adds a new member to the small population of known TeV binaries, and it identifies only the second source of this class in which the nature and properties of the compact object are firmly established. We compare the gamma-ray results with the light curve measured with the X-ray Telescope on board the Neil Gehrels Swift Observatory and with the predictions of recent theoretical models of the system. We conclude that significant revision of the models is required to explain the details of the emission that we have observed, and we discuss the relationship between the binary system and the overlapping steady extended source, TeV J2032+4130.
KW  - gamma rays: general
KW  - pulsars: individual (PSR J2032+4127, VER J2032+414, MAGIC J2032+4127)
KW  - stars: individual (MT91 213)
KW  - X-rays: binaries
Y1  - 2018
U6  - https://doi.org/10.3847/2041-8213/aae70e
SN  - 2041-8205
SN  - 2041-8213
VL  - 867
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  - 
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  - 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  -