TY - JOUR
A1 - Aliu, E.
A1 - Archambault, S.
A1 - Arlen, T.
A1 - Aune, T.
A1 - Beilicke, M.
A1 - Benbow, W.
A1 - Bouvier, A.
A1 - Bradbury, S. M.
A1 - Buckley, J. H.
A1 - Bugaev, V.
A1 - Byrum, K.
A1 - Cannon, A.
A1 - Cesarini, A.
A1 - Christiansen, J. L.
A1 - Ciupik, L.
A1 - Collins-Hughes, E.
A1 - Connolly, M. P.
A1 - Cui, W.
A1 - Decerprit, G.
A1 - Dickherber, R.
A1 - Dumm, J.
A1 - Errando, M.
A1 - Falcone, A.
A1 - Feng, Q.
A1 - Ferrer, F.
A1 - Finley, J. P.
A1 - Finnegan, G.
A1 - Fortson, L.
A1 - Furniss, A.
A1 - Galante, N.
A1 - Gall, D.
A1 - Godambe, S.
A1 - Griffin, S.
A1 - Grube, J.
A1 - Gyuk, G.
A1 - Hanna, D.
A1 - Holder, J.
A1 - Huan, H.
A1 - Hughes, G.
A1 - Humensky, T. B.
A1 - Kaaret, P.
A1 - Karlsson, N.
A1 - Kertzman, M.
A1 - Khassen, Y.
A1 - Kieda, D.
A1 - Krawczynski, H.
A1 - Krennrich, F.
A1 - Lee, K.
A1 - Madhavan, A. S.
A1 - Maier, G.
A1 - Majumdar, P.
A1 - McArthur, S.
A1 - McCann, A.
A1 - Moriarty, P.
A1 - Mukherjee, R.
A1 - Ong, R. A.
A1 - Orr, M.
A1 - Otte, A. N.
A1 - Park, N.
A1 - Perkins, J. S.
A1 - Pohl, Martin
A1 - Prokoph, H.
A1 - Quinn, J.
A1 - Ragan, K.
A1 - Reyes, L. C.
A1 - Reynolds, P. T.
A1 - Roache, E.
A1 - Rose, H. J.
A1 - Ruppel, J.
A1 - Saxon, D. B.
A1 - Schroedter, M.
A1 - Sembroski, G. H.
A1 - Sentuerk, G. D.
A1 - Skole, C.
A1 - Smith, A. W.
A1 - Staszak, D.
A1 - Telezhinsky, Igor
A1 - Tesic, G.
A1 - Theiling, M.
A1 - Thibadeau, S.
A1 - Tsurusaki, K.
A1 - Varlotta, A.
A1 - Vassiliev, V. V.
A1 - Vincent, S.
A1 - Vivier, M.
A1 - Wagner, R. G.
A1 - Wakely, S. P.
A1 - Ward, J. E.
A1 - Weekes, T. C.
A1 - Weinstein, A.
A1 - Weisgarber, T.
A1 - Williams, D. A.
A1 - Zitzer, B.
T1 - VERITAS deep observations of the dwarf spheroidal galaxy Segue 1
JF - Physical review : D, Particles, fields, gravitation, and cosmology
N2 - The VERITAS array of Cherenkov telescopes has carried out a deep observational program on the nearby dwarf spheroidal galaxy Segue 1. We report on the results of nearly 48 hours of good quality selected data, taken between January 2010 and May 2011. No significant gamma-ray emission is detected at the nominal position of Segue 1, and upper limits on the integrated flux are derived. According to recent studies, Segue 1 is the most dark matter-dominated dwarf spheroidal galaxy currently known. We derive stringent bounds on various annihilating and decaying dark matter particle models. The upper limits on the velocity-weighted annihilation cross-section are (95%) (CL) less than or similar to 10(-23) cm(3) s(-1), improving our limits from previous observations of dwarf spheroidal galaxies by at least a factor of 2 for dark matter particle masses m(chi) greater than or similar to 300 GeV. The lower limits on the decay lifetime are at the level of tau(95%) (CL) greater than or similar to 10(24) s. Finally, we address the interpretation of the cosmic ray lepton anomalies measured by ATIC and PAMELA in terms of dark matter annihilation, and show that the VERITAS observations of Segue 1 disfavor such a scenario.
Y1 - 2012
U6 - http://dx.doi.org/10.1103/PhysRevD.85.062001
SN - 1550-7998 (print)
VL - 85
IS - 6
PB - American Physical Society
CY - College Park
ER -
TY - JOUR
A1 - Aliu, E.
A1 - Archambault, S.
A1 - Arlen, T.
A1 - Aune, T.
A1 - Beilicke, M.
A1 - Benbow, W.
A1 - Boettcher, M.
A1 - Bouvier, A.
A1 - Buckley, J. H.
A1 - Bugaev, V.
A1 - Cesarini, A.
A1 - Ciupik, L.
A1 - Collins-Hughes, E.
A1 - Connolly, M. P.
A1 - Cui, W.
A1 - Dickherber, R.
A1 - Duke, C.
A1 - Dumm, J.
A1 - Errando, M.
A1 - Falcone, A.
A1 - Federici, Simone
A1 - Feng, Q.
A1 - Finley, J. P.
A1 - Finnegan, G.
A1 - Fortson, L.
A1 - Furniss, A.
A1 - Galante, N.
A1 - Gall, D.
A1 - Godambe, S.
A1 - Griffin, S.
A1 - Grube, J.
A1 - Gyuk, G.
A1 - Hanna, D.
A1 - Holder, J.
A1 - Huan, H.
A1 - Kaaret, P.
A1 - Karlsson, N.
A1 - Khassen, Y.
A1 - Kieda, D.
A1 - Krawczynski, H.
A1 - Krennrich, F.
A1 - Lee, K.
A1 - Madhavan, A. S.
A1 - Maier, G.
A1 - Majumdar, P.
A1 - McArthur, S.
A1 - McCann, A.
A1 - Moriarty, P.
A1 - Mukherjee, R.
A1 - Nelson, T.
A1 - de Bhroithe, A. O'Faolain
A1 - Ong, R. A.
A1 - Orr, M.
A1 - Otte, A. N.
A1 - Park, N.
A1 - Perkins, J. S.
A1 - Pichel, A.
A1 - Pohl, Martin
A1 - Prokoph, H.
A1 - Quinn, J.
A1 - Ragan, K.
A1 - Reyes, L. C.
A1 - Reynolds, P. T.
A1 - Roache, E.
A1 - Saxon, D. B.
A1 - Sembroski, G. H.
A1 - Staszak, D.
A1 - Telezhinsky, Igor
A1 - Tesic, G.
A1 - Theiling, M.
A1 - Thibadeau, S.
A1 - Tsurusaki, K.
A1 - Varlotta, A.
A1 - Vassiliev, V. V.
A1 - Vincent, S.
A1 - Vivier, M.
A1 - Wakely, S. P.
A1 - Weekes, T. C.
A1 - Weinstein, A.
A1 - Welsing, R.
A1 - Williams, D. A.
A1 - Zitzer, B.
A1 - Fortin, P.
A1 - Horan, D.
A1 - Fumagalli, M.
A1 - Kaplan, K.
A1 - Prochaska, J. X.
T1 - Veritas observations of six bright, hard-spectrum fermi-lat blazars
JF - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2 - We report on VERITAS very high energy (VHE; E >= 100 GeV) observations of six blazars selected from the Fermi Large Area Telescope First Source Catalog (1FGL). The gamma-ray emission from 1FGL sources was extrapolated up to the VHE band, taking gamma-ray absorption by the extragalactic background light into account. This allowed the selection of six bright, hard-spectrum blazars that were good candidate TeV emitters. Spectroscopic redshift measurements were attempted with the Keck Telescope for the targets without Sloan Digital Sky Survey spectroscopic data. No VHE emission is detected during the observations of the six sources described here. Corresponding TeV upper limits are presented, along with contemporaneous Fermi observations and non-concurrent Swift UVOT and X-Ray Telescope data. The blazar broadband spectral energy distributions (SEDs) are assembled and modeled with a single-zone synchrotron self-Compton model. The SED built for each of the six blazars shows a synchrotron peak bordering between the intermediate-and high-spectrum-peak classifications, with four of the six resulting in particle-dominated emission regions.
KW - BL Lacertae objects: general
KW - gamma rays: galaxies
Y1 - 2012
U6 - http://dx.doi.org/10.1088/0004-637X/759/2/102
SN - 0004-637X (print)
VL - 759
IS - 2
PB - IOP Publ. Ltd.
CY - Bristol
ER -
TY - JOUR
A1 - tAliu, E.
A1 - Archambault, S.
A1 - Arlen, T.
A1 - Aune, T.
A1 - Beilicke, M.
A1 - Benbow, W.
A1 - Bird, R.
A1 - Bouvier, A.
A1 - Bradbury, S. M.
A1 - Buckley, J. H.
A1 - Bugaev, V.
A1 - Byrum, K.
A1 - Cannon, A.
A1 - Cesarini, A.
A1 - Ciupik, L.
A1 - Collins-Hughes, E.
A1 - Connolly, M. P.
A1 - Cui, W.
A1 - Dickherber, R.
A1 - Duke, C.
A1 - Dumm, J.
A1 - Dwarkadas, V. V.
A1 - Errando, M.
A1 - Falcone, A.
A1 - Federici, Simone
A1 - Feng, Q.
A1 - Finley, J. P.
A1 - Finnegan, G.
A1 - Fortson, L.
A1 - Furniss, A.
A1 - Galante, N.
A1 - Gall, D.
A1 - Gillanders, G. H.
A1 - Godambe, S.
A1 - Gotthelf, E. V.
A1 - Griffin, S.
A1 - Grube, J.
A1 - Gyuk, G.
A1 - Hanna, D.
A1 - Holder, J.
A1 - Huan, H.
A1 - Hughes, G.
A1 - Humensky, T. B.
A1 - Kaaret, P.
A1 - Karlsson, N.
A1 - Kertzman, M.
A1 - Khassen, Y.
A1 - Kieda, D.
A1 - Krawczynski, H.
A1 - Krennrich, F.
A1 - Lang, M. J.
A1 - Lee, K.
A1 - Madhavan, A. S.
A1 - Maier, G.
A1 - Majumdar, P.
A1 - McArthur, S.
A1 - McCann, A.
A1 - Millis, J.
A1 - Moriarty, P.
A1 - Mukherjee, R.
A1 - Nelson, T.
A1 - de Bhroithe, A. O'Faolain
A1 - Ong, R. A.
A1 - Orr, M.
A1 - Otte, A. N.
A1 - Pandel, D.
A1 - Park, N.
A1 - Perkins, J. S.
A1 - Pohl, Martin
A1 - Popkow, A.
A1 - Prokoph, H.
A1 - Quinn, J.
A1 - Ragan, K.
A1 - Reyes, L. C.
A1 - Reynolds, P. T.
A1 - Roache, E.
A1 - Rose, H. J.
A1 - Ruppel, Jens
A1 - Saxon, D. B.
A1 - Schroedter, M.
A1 - Sembroski, G. H.
A1 - Sentuerk, G. D.
A1 - Skole, C.
A1 - Telezhinsky, Igor
A1 - Tesic, G.
A1 - Theiling, M.
A1 - Thibadeau, S.
A1 - Tsurusaki, K.
A1 - Tyler, J.
A1 - Varlotta, A.
A1 - Vassiliev, V. V.
A1 - Vincent, S.
A1 - Wakely, S. P.
A1 - Ward, J. E.
A1 - Weekes, T. C.
A1 - Weinstein, A.
A1 - Weisgarber, T.
A1 - Welsing, R.
A1 - Williams, D. A.
A1 - Zitzer, B.
T1 - Discovery of TeV Gamma-Ray emission toward supernova remnant SNR G78.2+2.1
JF - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2 - We report the discovery of an unidentified, extended source of very-high-energy gamma-ray emission, VER J2019+407, within the radio shell of the supernova remnant SNR G78.2+2.1, using 21.4 hr of data taken by the VERITAS gamma-ray observatory in 2009. These data confirm the preliminary indications of gamma-ray emission previously seen in a two-year (2007-2009) blind survey of the Cygnus region by VERITAS. VER J2019+407, which is detected at a post-trials significance of 7.5 standard deviations in the 2009 data, is localized to the northwestern rim of the remnant in a region of enhanced radio and X-ray emission. It has an intrinsic extent of 0 degrees.23 +/- 0 degrees.03(stat-0 degrees.02sys)(+0 degrees.04) and its spectrum is well-characterized by a differential power law (dN/dE = N-0 x (E/TeV)-Gamma) with a photon index of Gamma = 2.37 +/- 0.14(stat) +/- 0.20(sys) and a flux normalization of N-0 = 1.5 +/- 0.2(stat) +/- 0.4(sys) x 10(-12) photon TeV-1 cm(-2) s(-1). This yields an integral flux of 5.2 +/- 0.8(stat) +/- 1.4(sys) x 10(-12) photon cm(-2) s(-1) above 320 GeV, corresponding to 3.7% of the Crab Nebula flux. We consider the relationship of the TeV gamma-ray emission with the GeV gamma-ray emission seen from SNR G78.2+2.1 as well as that seen from a nearby cocoon of freshly accelerated cosmic rays. Multiple scenarios are considered as possible origins for the TeV gamma-ray emission, including hadronic particle acceleration at the SNR shock.
KW - acceleration of particles
KW - cosmic rays
KW - gamma rays: general
KW - ISM: supernova remnants
Y1 - 2013
U6 - http://dx.doi.org/10.1088/0004-637X/770/2/93
SN - 0004-637X (print)
VL - 770
IS - 2
PB - IOP Publ. Ltd.
CY - Bristol
ER -
TY - JOUR
A1 - Aliu, E.
A1 - Archambault, S.
A1 - Behera, B.
A1 - Berger, K.
A1 - Beilicke, M.
A1 - Benbow, W.
A1 - Bird, R.
A1 - Bouvier, A.
A1 - Bugaev, V.
A1 - Cerruti, M.
A1 - Chen, Xuhui
A1 - Ciupik, L.
A1 - Connolly, M. P.
A1 - Cui, W.
A1 - Dumm, J.
A1 - Falcone, A.
A1 - Federici, Simone
A1 - Feng, Q.
A1 - Finley, J. P.
A1 - Fortin, P.
A1 - Fortson, L.
A1 - Furniss, A.
A1 - Galante, N.
A1 - Gillanders, G. H.
A1 - Griffin, S.
A1 - Griffiths, S. T.
A1 - Grube, J.
A1 - Gyuk, G.
A1 - Hanna, D.
A1 - Holder, J.
A1 - Hughes, G.
A1 - Humensky, T. B.
A1 - Kaaret, P.
A1 - Kertzman, M.
A1 - Khassen, Y.
A1 - Kieda, D.
A1 - Krennrich, F.
A1 - Lang, M. J.
A1 - Maier, G.
A1 - Majumdar, P.
A1 - McArthur, S.
A1 - McCann, A.
A1 - Moriarty, P.
A1 - Mukherjee, R.
A1 - de Bhroithe, A. O'Faolain
A1 - Ong, R. A.
A1 - Otte, A. N.
A1 - Park, N.
A1 - Perkins, J. S.
A1 - Pohl, Martin
A1 - Popkow, A.
A1 - Prokoph, H.
A1 - Quinn, J.
A1 - Ragan, K.
A1 - Rajotte, J.
A1 - Ratliff, G.
A1 - Reynolds, P. T.
A1 - Richards, G. T.
A1 - Roache, E.
A1 - Sembroski, G. H.
A1 - Sheidaei, F.
A1 - Skole, C.
A1 - Smith, A. W.
A1 - Staszak, D.
A1 - Telezhinsky, Igor
A1 - Tyler, J.
A1 - Varlotta, A.
A1 - Vincent, S.
A1 - Wakely, S. P.
A1 - Weekes, T. C.
A1 - Weinstein, A.
A1 - Welsing, R.
A1 - Zajczyk, A.
A1 - Zitzer, B.
T1 - Multiwavelemght oservatons of the TeV binary LS I+61 degrees 303 with veritas, fermi-lat, and swift/XRT during a TeV outburst
JF - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2 - We present the results of a multiwavelength observational campaign on the TeV binary system LS I +61 degrees 303 with the VERITAS telescope array (>200 GeV), Fermi-LAT (0.3-300 GeV), and Swift/XRT (2-10 keV). The data were taken from 2011 December through 2012 January and show a strong detection in all three wavebands. During this period VERITAS obtained 24.9 hr of quality selected livetime data in which LS I +61 degrees 303 was detected at a statistical significance of 11.9 sigma. These TeV observations show evidence for nightly variability in the TeV regime at a post-trial significance of 3.6 sigma. The combination of the simultaneously obtained TeV and X-ray fluxes do not demonstrate any evidence for a correlation between emission in the two bands. For the first time since the launch of the Fermi satellite in 2008, this TeV detection allows the construction of a detailed MeV-TeV spectral energy distribution from LS I +61 degrees 303. This spectrum shows a distinct cutoff in emission near 4 GeV, with emission seen by the VERITAS observations following a simple power-law above 200 GeV. This feature in the spectrum of LS I +61 degrees 303, obtained from overlapping observations with Fermi-LAT and VERITAS, may indicate that there are two distinct populations of accelerated particles producing the GeV and TeV emission.
KW - acceleration of particles
KW - binaries: general
KW - gamma rays: stars
KW - relativistic processes
KW - X-rays: binaries
Y1 - 2013
U6 - http://dx.doi.org/10.1088/0004-637X/779/1/88
SN - 0004-637X (print)
SN - 1538-4357 (online)
VL - 779
IS - 1
PB - IOP Publ. Ltd.
CY - Bristol
ER -
TY - JOUR
A1 - Aliu, E.
A1 - Archambault, S.
A1 - Arlen, T.
A1 - Aune, T.
A1 - Beilicke, M.
A1 - Benbow, W.
A1 - Bird, R.
A1 - Boettcher, M.
A1 - Bouvier, A.
A1 - Bugaev, V.
A1 - Byrum, K.
A1 - Cesarini, A.
A1 - Ciupik, L.
A1 - Collins-Hughes, E.
A1 - Connolly, M. P.
A1 - Cui, W.
A1 - Dickherber, R.
A1 - Duke, C.
A1 - Dumm, J.
A1 - Errando, M.
A1 - Falcone, A.
A1 - Federici, Simone
A1 - Feng, Q.
A1 - Finley, J. P.
A1 - Finnegan, G.
A1 - Fortson, L.
A1 - Furniss, A.
A1 - Galante, N.
A1 - Gall, D.
A1 - Gillanders, G. H.
A1 - Griffin, S.
A1 - Grube, J.
A1 - Gyuk, G.
A1 - Hanna, D.
A1 - Holder, J.
A1 - Hughes, G.
A1 - Humensky, T. B.
A1 - Kaaret, P.
A1 - Kertzman, M.
A1 - Khassen, Y.
A1 - Kieda, D.
A1 - Krawczynski, H.
A1 - Krennrich, F.
A1 - Lang, M. J.
A1 - Madhavan, A. S.
A1 - Maier, G.
A1 - Majumdar, P.
A1 - McArthur, S.
A1 - McCann, A.
A1 - Moriarty, P.
A1 - Mukherjee, R.
A1 - Nelson, T.
A1 - de Bhroithe, A. O'Faolain
A1 - Ong, R. A.
A1 - Orr, M.
A1 - Otte, A. N.
A1 - Park, N.
A1 - Perkins, J. S.
A1 - Pichel, A.
A1 - Pohl, Martin
A1 - Popkow, A.
A1 - Prokoph, H.
A1 - Quinn, J.
A1 - Ragan, K.
A1 - Reyes, L. C.
A1 - Reynolds, P. T.
A1 - Roache, E.
A1 - Saxon, D. B.
A1 - Schroedter, M.
A1 - Sembroski, G. H.
A1 - Skole, C.
A1 - Smith, A. W.
A1 - Staszak, D.
A1 - Telezhinsky, Igor
A1 - Theiling, M.
A1 - Tyler, J.
A1 - Varlotta, A.
A1 - Vassiliev, V. V.
A1 - Wakely, S. P.
A1 - Weekes, T. C.
A1 - Weinstein, A.
A1 - Welsing, R.
A1 - Williams, D. A.
A1 - Zitzer, B.
T1 - Multiwavelenght observations and modeling of 1ES 1959+650 in a low flux state
JF - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2 - We report on the VERITAS observations of the high-frequency peaked BL Lac object 1ES 1959+650 in the period 2007-2011. This source is detected at TeV energies by VERITAS at 16.4 standard deviation (sigma) significance in 7.6 hr of observation in a low flux state. A multiwavelength spectral energy distribution (SED) is constructed from contemporaneous data from VERITAS, Fermi-LAT, RXTE PCA, and Swift UVOT. Swift XRT data is not included in the SED due to a lack of simultaneous observations with VERITAS. In contrast to the orphan gamma-ray flare exhibited by this source in 2002, the X-ray flux of the source is found to vary by an order of magnitude, while other energy regimes exhibit less variable emission. A quasi-equilibrium synchrotron self-Compton model with an additional external radiation field is used to describe three SEDs corresponding to the lowest, highest, and average X-ray states. The variation in the X-ray spectrum is modeled by changing the electron injection spectral index, with minor adjustments of the kinetic luminosity in electrons. This scenario produces small-scale flux variability of the order of less than or similar to 2 in the high energy (E > 1MeV) and very high energy (E > 100 GeV) gamma-ray regimes, which is corroborated by the Fermi-LAT, VERITAS, and Whipple 10 m telescope light curves.
KW - BL Lacertae objects: general
KW - BL Lacertae objects: individual (1ES 1959+650=VER J1959+651)
KW - galaxies: active
KW - gamma rays: galaxies
Y1 - 2013
U6 - http://dx.doi.org/10.1088/0004-637X/775/1/3
SN - 0004-637X (print)
VL - 775
IS - 1
PB - IOP Publ. Ltd.
CY - Bristol
ER -
TY - JOUR
A1 - Archambault, S.
A1 - Arlen, T.
A1 - Aune, T.
A1 - Behera, B.
A1 - Beilicke, M.
A1 - Benbow, W.
A1 - Bird, R.
A1 - Bouvier, A.
A1 - Buckley, J. H.
A1 - Bugaev, V.
A1 - Byrum, K.
A1 - Cesarini, A.
A1 - Ciupik, L.
A1 - Connolly, M. P.
A1 - Cui, W.
A1 - Errando, M.
A1 - Falcone, A.
A1 - Federici, Simone
A1 - Feng, Q.
A1 - Finley, J. P.
A1 - Fortson, L.
A1 - Furniss, A.
A1 - Galante, N.
A1 - Gall, D.
A1 - Gillanders, G. H.
A1 - Griffin, S.
A1 - Grube, J.
A1 - Gyuk, G.
A1 - Hanna, D.
A1 - Holder, J.
A1 - Hughes, G.
A1 - Humensky, T. B.
A1 - Kaaret, P.
A1 - Kertzman, M.
A1 - Khassen, Y.
A1 - Kieda, D.
A1 - Krawczynski, H.
A1 - Krennrich, F.
A1 - Kumar, S.
A1 - Lang, M. J.
A1 - Madhavan, A. S.
A1 - Maier, G.
A1 - Majumdar, P.
A1 - McArthur, S.
A1 - McCann, A.
A1 - Millis, J.
A1 - Moriarty, P.
A1 - Mukherjee, R.
A1 - de Bhroithe, A. O'Faolain
A1 - Ong, R. A.
A1 - Otte, A. N.
A1 - Park, N.
A1 - Perkins, J. S.
A1 - Pohl, Martin
A1 - Popkow, A.
A1 - Prokoph, H.
A1 - Quinn, J.
A1 - Ragan, K.
A1 - Reyes, L. C.
A1 - Reynolds, P. T.
A1 - Richards, G. T.
A1 - Roache, E.
A1 - Saxon, D. B.
A1 - Sembroski, G. H.
A1 - Smith, A. W.
A1 - Staszak, D.
A1 - Telezhinsky, Igor
A1 - Theiling, M.
A1 - Varlotta, A.
A1 - Vassiliev, V. V.
A1 - Vincent, S.
A1 - Wakely, S. P.
A1 - Weekes, T. C.
A1 - Weinstein, A.
A1 - Welsing, R.
A1 - Williams, D. A.
A1 - Zitzer, B.
A1 - Boettcher, M.
A1 - Fegan, S. J.
A1 - Fortin, P.
A1 - Halpern, J. P.
A1 - Kovalev, Y. Y.
A1 - Lister, M. L.
A1 - Liu, J.
A1 - Pushkarev, A. B.
A1 - Smith, P. S.
T1 - Discovery of a new tev Gamma-Ray source - VER J0521+211
JF - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2 - We report the detection of a new TeV gamma-ray source, VER J0521+211, based on observations made with the VERITAS imaging atmospheric Cherenkov Telescope Array. These observations were motivated by the discovery of a cluster of >30 GeV photons in the first year of Fermi Large Area Telescope observations. VER J0521+211 is relatively bright at TeV energies, with a mean photon flux of (1.93 +/- 0.13(stat) +/- 0.78(sys)) x 10(-11) cm(-2) s(-1) above 0.2 TeV during the period of the VERITAS observations. The source is strongly variable on a daily timescale across all wavebands, from optical to TeV, with a peak flux corresponding to similar to 0.3 times the steady Crab Nebula flux at TeV energies. Follow-up observations in the optical and X-ray bands classify the newly discovered TeV source as a BL Lac-type blazar with uncertain redshift, although recent measurements suggest z = 0.108. VER J0521+211 exhibits all the defining properties of blazars in radio, optical, X-ray, and gamma-ray wavelengths.
KW - BL Lacertae objects: individual (VER J0521+211)
KW - gamma rays: galaxies
Y1 - 2013
U6 - http://dx.doi.org/10.1088/0004-637X/776/2/69
SN - 0004-637X (print)
SN - 1538-4357 (online)
VL - 776
IS - 2
PB - IOP Publ. Ltd.
CY - Bristol
ER -
TY - JOUR
A1 - Archambault, S.
A1 - Beilicke, M.
A1 - Benbow, W.
A1 - Berger, K.
A1 - Bird, R.
A1 - Bouvier, A.
A1 - Buckley, J. H.
A1 - Bugaev, V.
A1 - Byrum, K.
A1 - Cerruti, M.
A1 - Chen, Xuhui
A1 - Ciupik, L.
A1 - Connolly, M. P.
A1 - Cui, W.
A1 - Duke, C.
A1 - Dumm, J.
A1 - Errando, M.
A1 - Falcone, A.
A1 - Federici, Simone
A1 - Feng, Q.
A1 - Finley, J. P.
A1 - Fortson, L.
A1 - Furniss, A.
A1 - Galante, N.
A1 - Gillanders, G. H.
A1 - Griffin, S.
A1 - Griffiths, S. T.
A1 - Grube, J.
A1 - Gyuk, G.
A1 - Hanna, D.
A1 - Holder, J.
A1 - Hughes, G.
A1 - Humensky, T. B.
A1 - Kaaret, P.
A1 - Kertzman, M.
A1 - Khassen, Y.
A1 - Kieda, D.
A1 - Krawczynski, H.
A1 - Lang, M. J.
A1 - Madhavan, A. S.
A1 - Maier, G.
A1 - Majumdar, P.
A1 - McArthur, S.
A1 - McCann, A.
A1 - Moriarty, P.
A1 - Mukherjee, R.
A1 - Nieto, D.
A1 - de Bhroithe, A. O'Faolain
A1 - Ong, R. A.
A1 - Otte, A. N.
A1 - Pandel, D.
A1 - Park, N.
A1 - Perkins, J. S.
A1 - Pohl, Martin
A1 - Popkow, A.
A1 - Prokoph, H.
A1 - Quinn, J.
A1 - Ragan, K.
A1 - Rajotte, J.
A1 - Reyes, L. C.
A1 - Reynolds, P. T.
A1 - Richards, G. T.
A1 - Roache, E.
A1 - Sembroski, G. H.
A1 - Sheidaei, F.
A1 - Smith, A. W.
A1 - Staszak, D.
A1 - Telezhinsky, Igor
A1 - Theiling, M.
A1 - Tucci, J. V.
A1 - Tyler, J.
A1 - Varlotta, A.
A1 - Vincent, S.
A1 - Wakely, S. P.
A1 - Weekes, T. C.
A1 - Weinstein, A.
A1 - Williams, D. A.
A1 - Zitzer, B.
A1 - McCollough, M. L.
T1 - Veritas observatons of the microquasar cygnus X-3
JF - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2 - We report results from TeV gamma-ray observations of the microquasar Cygnus X-3. The observations were made with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) over a time period from 2007 June 11 to 2011 November 28. VERITAS is most sensitive to gamma rays at energies between 85 GeV and 30 TeV. The effective exposure time amounts to a total of about 44 hr, with the observations covering six distinct radio/X-ray states of the object. No significant TeV gamma-ray emission was detected in any of the states, nor with all observations combined. The lack of a positive signal, especially in the states where GeV gamma rays were detected, places constraints on TeV gamma-ray production in Cygnus X-3. We discuss the implications of the results.
KW - acceleration of particles
KW - binaries: close
KW - gamma rays: stars
KW - X-rays: individual (Cygnus X-3)
Y1 - 2013
U6 - http://dx.doi.org/10.1088/0004-637X/779/2/150
SN - 0004-637X (print)
SN - 1538-4357 (online)
VL - 779
IS - 2
PB - IOP Publ. Ltd.
CY - Bristol
ER -
TY - JOUR
A1 - Archambault, S.
A1 - Aune, T.
A1 - Behera, B.
A1 - Beilicke, M.
A1 - Benbow, W.
A1 - Berger, K.
A1 - Bird, R.
A1 - Biteau, J.
A1 - Bugaev, V.
A1 - Byrum, K.
A1 - Cardenzana, J. V.
A1 - Cerruti, M.
A1 - Chen, Xuhui
A1 - Ciupik, L.
A1 - Connolly, M. P.
A1 - Cui, Wei
A1 - Dumm, J.
A1 - Errando, M.
A1 - Falcone, A.
A1 - Federici, Simone
A1 - Feng, Q.
A1 - Finley, J. P.
A1 - Fleischhack, H.
A1 - Fortson, L.
A1 - Furniss, A.
A1 - Galante, N.
A1 - Gillanders, G. H.
A1 - Griffin, S.
A1 - Griffiths, S. T.
A1 - Grube, J.
A1 - Gyuk, G.
A1 - Hanna, D.
A1 - Holder, J.
A1 - Hughes, G.
A1 - Humensky, T. B.
A1 - Johnson, C. A.
A1 - Kaaret, P.
A1 - Kertzman, M.
A1 - Khassen, Y.
A1 - Kieda, D.
A1 - Krawczynski, H.
A1 - Krennrich, F.
A1 - Kumar, S.
A1 - Lang, M. J.
A1 - Madhavan, A. S.
A1 - Maier, G.
A1 - McCann, A.
A1 - Meagher, K.
A1 - Moriarty, P.
A1 - Mukherjee, R.
A1 - Nieto, Daniel
A1 - Ong, R. A.
A1 - Otte, A. N.
A1 - Park, N.
A1 - Pohl, Martin
A1 - Popkow, A.
A1 - Prokoph, H.
A1 - Quinn, J.
A1 - Ragan, K.
A1 - Rajotte, J.
A1 - Reyes, L. C.
A1 - Reynolds, P. T.
A1 - Richards, G. T.
A1 - Roache, E.
A1 - Sembroski, G. H.
A1 - Shahinyan, K.
A1 - Staszak, D.
A1 - Telezhinsky, Igor
A1 - Tucci, J. V.
A1 - Tyler, J.
A1 - Varlotta, A.
A1 - Vassiliev, V. V.
A1 - Vincent, S.
A1 - Wakely, S. P.
A1 - Weinstein, A.
A1 - Welsing, R.
A1 - Wilhelm, Alina
A1 - Williams, D. A.
A1 - Ackermann, Margit
A1 - Ajello, M.
A1 - Albert, A.
A1 - Baldini, L.
A1 - Bastieri, D.
A1 - Bellazzini, R.
A1 - Bissaldi, E.
A1 - Bregeon, J.
A1 - Buehler, R.
A1 - Buson, S.
A1 - Caliandro, G. A.
A1 - Cameron, R. A.
A1 - Caraveo, P. A.
A1 - Cavazzuti, E.
A1 - Charles, E.
A1 - Chiang, J.
A1 - Ciprini, S.
A1 - Claus, R.
A1 - Cutini, S.
A1 - de Angelis, A.
A1 - de Palma, F.
A1 - Dermer, C. D.
A1 - Digel, S. W.
A1 - Di Venere, L.
A1 - Drell, P. S.
A1 - Favuzzi, C.
A1 - Franckowiak, A.
A1 - Fusco, P.
A1 - Gargano, F.
A1 - Gasparrini, D.
A1 - Giglietto, N.
A1 - Giordano, F.
A1 - Giroletti, M.
A1 - Grenier, I. A.
A1 - Guiriec, S.
A1 - Jogler, T.
A1 - Kuss, M.
A1 - Larsson, S.
A1 - Latronico, L.
A1 - Longo, F.
A1 - Loparco, F.
A1 - Lubrano, P.
A1 - Madejski, G. M.
A1 - Mayer, M.
A1 - Mazziotta, M. N.
A1 - Michelson, P. F.
A1 - Mizuno, T.
A1 - Monzani, M. E.
A1 - Morselli, Aldo
A1 - Murgia, S.
A1 - Nuss, E.
A1 - Ohsugi, T.
A1 - Ormes, J. F.
A1 - Paneque, D.
A1 - Perkins, J. S.
A1 - Piron, F.
A1 - Pivato, G.
A1 - Raino, S.
A1 - Razzano, M.
A1 - Reimer, A.
A1 - Reimer, Olaf
A1 - Ritz, S.
A1 - Schaal, M.
A1 - Sgro, C.
A1 - Siskind, E. J.
A1 - Spinelli, P.
A1 - Takahashi, H.
A1 - Tibaldo, L.
A1 - Tinivella, M.
A1 - Troja, E.
A1 - Vianello, G.
A1 - Werner, M.
A1 - Wood, M.
T1 - Deep broadband observations of the distant gamma-ray blazar PKS 1424+240
JF - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters
N2 - We present deep VERITAS observations of the blazar PKS 1424+240, along with contemporaneous Fermi Large Area Telescope, Swift X-ray Telescope, and Swift UV Optical Telescope data between 2009 February 19 and 2013 June 8. This blazar resides at a redshift of z >= 0.6035, displaying a significantly attenuated gamma-ray flux above 100 GeV due to photon absorption via pair-production with the extragalactic background light. We present more than 100 hr of VERITAS observations over three years, a multiwavelength light curve, and the contemporaneous spectral energy distributions. The source shows a higher flux of (2.1 +/- 0.3) x 10(-7) photons m(-2) s(-1) above 120 GeV in 2009 and 2011 as compared to the flux measured in 2013, corresponding to (1.02 +/- 0.08) x 10-7 photons m(-2) s(-1) above 120 GeV. The measured differential very high energy (VHE; E >= 100 GeV) spectral indices are Gamma = 3.8 +/- 0.3, 4.3 +/- 0.6 and 4.5 +/- 0.2 in 2009, 2011, and 2013, respectively. No significant spectral change across the observation epochs is detected. We find no evidence for variability at gamma-ray opacities of greater than tau = 2, where it is postulated that any variability would be small and occur on timescales longer than a year if hadronic cosmic-ray interactions with extragalactic photon fields provide a secondary VHE photon flux. The data cannot rule out such variability due to low statistics.
KW - BL Lacertae objects: individual (PKS 1424+240)-cosmic background radiation
KW - gamma rays: galaxies
Y1 - 2014
U6 - http://dx.doi.org/10.1088/2041-8205/785/1/L16
SN - 2041-8205 (print)
SN - 2041-8213 (online)
VL - 785
IS - 1
PB - IOP Publ. Ltd.
CY - Bristol
ER -
TY - JOUR
A1 - Archambault, S.
A1 - Arlen, T.
A1 - Aune, T.
A1 - Beilicke, M.
A1 - Benbow, W.
A1 - Bird, R.
A1 - Boettcher, M.
A1 - Bouvier, A.
A1 - Buckley, J. H.
A1 - Bugaev, V.
A1 - Ciupik, L.
A1 - Collins-Hughes, E.
A1 - Connolly, M. P.
A1 - Cui, W.
A1 - Dickherber, R.
A1 - Dumm, J.
A1 - Errando, M.
A1 - Falcone, A.
A1 - Federici, Simone
A1 - Feng, Q.
A1 - Finley, J. P.
A1 - Fortson, L.
A1 - Furniss, A.
A1 - Galante, N.
A1 - Gall, D.
A1 - Garson, A. III.
A1 - Gillanders, G. H.
A1 - Griffin, S.
A1 - Grube, J.
A1 - Gusbar, C.
A1 - Gyuk, G.
A1 - Hanna, D.
A1 - Holder, J.
A1 - Hughes, G.
A1 - Kaaret, P.
A1 - Kertzman, M.
A1 - Khassen, Y.
A1 - Kieda, D.
A1 - Krawczynski, H.
A1 - Lamerato, A.
A1 - Lang, M. J.
A1 - Li, K.
A1 - Madhavan, A. S.
A1 - Maier, G.
A1 - Majumdar, P.
A1 - McArthur, S.
A1 - McCann, A.
A1 - Millis, J.
A1 - Moriarty, P.
A1 - Mukherjee, R.
A1 - Nieto, D.
A1 - Ong, R. A.
A1 - Orr, M.
A1 - Otte, A. N.
A1 - Park, N.
A1 - Perkins, J. S.
A1 - Pohl, Martin
A1 - Popkow, A.
A1 - Prokoph, H.
A1 - Quinn, J.
A1 - Ragan, K.
A1 - Reynolds, P. T.
A1 - Richards, G. T.
A1 - Roache, E.
A1 - Roustazadeh, P.
A1 - Saxon, D. B.
A1 - Sembroski, G. H.
A1 - Senturk, G. D.
A1 - Skole, C.
A1 - Staszak, D.
A1 - Telezhinsky, Igor
A1 - Tesic, G.
A1 - Theiling, M.
A1 - Varlotta, A.
A1 - Vassiliev, V. V.
A1 - Vincent, S.
A1 - Wakely, S. P.
A1 - Weinstein, A.
A1 - Welsing, R.
A1 - Williams, D. A.
A1 - Zitzer, B.
T1 - Test of models of the cosmic infrared background with multiwavelength observations of the blazar 1ES 1218+30.4 IN 2009
JF - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2 - We present the results of a multi-wavelength campaign targeting the blazar 1ES 1218+30.4 with observations with the 1.3 m McGraw-Hill optical telescope, the Rossi X-ray Timing Explorer (RXTE), the Fermi Gamma-Ray Space Telescope, and the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The RXTE and VERITAS observations were spread over a 13 day period and revealed clear evidence for flux variability, and a strong X-ray and gamma-ray flare on 2009 February 26 (MJD 54888). The campaign delivered a well-sampled broadband energy spectrum with simultaneous RXTE and VERITAS very high energy (VHE, > 100 GeV) observations, as well as contemporaneous optical and Fermi observations. The 1ES 1218+30.4 broadband energy spectrum-the first with simultaneous X-ray and VHE gamma-ray energy spectra-is of particular interest as the source is located at a high cosmological redshift for a VHE source (z = 0.182), leading to strong absorption of VHE gamma rays by photons from the optical/infrared extragalactic background light (EBL) via gamma VHE +gamma EBL -> e(+) e(-)pair-creation processes. We model the data with a one-zone synchrotron self-Compton (SSC) emission model and with the extragalactic absorption predicted by several recent EBL models. We find that the observations are consistent with the SSC scenario and all the EBL models considered in this work. We discuss observational and theoretical avenues to improve on the EBL constraints.
KW - BL Lacertae objects: general
KW - BL Lacertae objects: individual (1ES1218+30.4)
KW - cosmic background radiation
KW - diffuse radiation
KW - galaxies: jets
KW - gamma rays: galaxies
Y1 - 2014
U6 - http://dx.doi.org/10.1088/0004-637X/788/2/158
SN - 0004-637X (print)
SN - 1538-4357 (online)
VL - 788
IS - 2
PB - IOP Publ. Ltd.
CY - Bristol
ER -
TY - JOUR
A1 - Aliu, E.
A1 - Aune, T.
A1 - Behera, B.
A1 - Beilicke, M.
A1 - Benbow, W.
A1 - Berger, K.
A1 - Bird, R.
A1 - Bouvier, A.
A1 - Buckley, J. H.
A1 - Bugaev, V.
A1 - Cerruti, M.
A1 - Chen, Xuhui
A1 - Ciupik, L.
A1 - Connolly, M. P.
A1 - Cui, W.
A1 - Dumm, J.
A1 - Dwarkadas, V. V.
A1 - Errando, M.
A1 - Falcone, A.
A1 - Federici, Simone
A1 - Feng, Q.
A1 - Finley, J. P.
A1 - Fleischhack, H.
A1 - Fortin, P.
A1 - Fortson, L.
A1 - Furniss, A.
A1 - Galante, N.
A1 - Gillanders, G. H.
A1 - Gotthelf, E. V.
A1 - Griffin, S.
A1 - Griffiths, S. T.
A1 - Grube, J.
A1 - Gyuk, G.
A1 - Hanna, D.
A1 - Holder, J.
A1 - Hughes, G.
A1 - Humensky, T. B.
A1 - Johnson, C. A.
A1 - Kaaret, P.
A1 - Kargaltsev, O.
A1 - Kertzman, M.
A1 - Khassen, Y.
A1 - Kieda, D.
A1 - Krennrich, F.
A1 - Lang, M. J.
A1 - Madhavan, A. S.
A1 - Maier, G.
A1 - McArthur, S.
A1 - McCann, A.
A1 - Millis, J.
A1 - Moriarty, P.
A1 - Mukherjee, R.
A1 - Nieto, D.
A1 - Ong, R. A.
A1 - Otte, A. N.
A1 - Pandel, D.
A1 - Park, N.
A1 - Pohl, Martin
A1 - Popkow, A.
A1 - Prokoph, H.
A1 - Quinn, J.
A1 - Ragan, K.
A1 - Rajotte, J.
A1 - Reyes, L. C.
A1 - Reynolds, P. T.
A1 - Richards, G. T.
A1 - Roache, E.
A1 - Roberts, M.
A1 - Sembroski, G. H.
A1 - Shahinyan, K.
A1 - Smith, A. W.
A1 - Staszak, D.
A1 - Telezhinsky, Igor
A1 - Tucci, J. V.
A1 - Tyler, J.
A1 - Vincent, S.
A1 - Wakely, S. P.
A1 - Weinstein, A.
A1 - Welsing, R.
A1 - Wilhelm, Alina
A1 - Williams, D. A.
A1 - Zitzer, B.
T1 - Spatially resolving the very high energy emission from MRGO J2019+37 wih veritas
JF - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2 - We present very high energy (VHE) imaging of MGRO J2019+37 obtained with the VERITAS observatory. The bright extended (similar to 2 degrees) unidentified Milagro source is located toward the rich star formation region Cygnus-X. MGRO J2019+37 is resolved into two VERITAS sources. The faint, point-like source VER J2016+371 overlaps CTB 87, a filled-center remnant (SNR) with no evidence of a supernova remnant shell at the present time. Its spectrum is well fit in the 0.65-10 TeV energy range by a power-law model with photon index 2.3 +/- 0.4. VER J2019+378 is a bright extended (similar to 1 degrees) source that likely accounts for the bulk of the Milagro emission and is notably coincident with PSR J2021+3651 and the star formation region Sh 2-104. Its spectrum in the range 1-30 TeV is well fit with a power-law model of photon index 1.75 +/- 0.3, among the hardest values measured in the VHE band, comparable to that observed near Vela-X. We explore the unusual spectrum and morphology in the radio and X-ray bands to constrain possible emission mechanisms for this source.
KW - gamma rays : stars
KW - pulsars : individual (PSR J2021+3651)
KW - supernovae : individual (CTB 87)
Y1 - 2014
U6 - http://dx.doi.org/10.1088/0004-637X/788/1/78
SN - 0004-637X (print)
SN - 1538-4357 (online)
VL - 788
IS - 1
PB - IOP Publ. Ltd.
CY - Bristol
ER -