@article{AliuArchambaultArcheretal.2016,
  author    = {Aliu, E. and Archambault, S. and Archer, A. and Arlen, T. and Aune, T. and Barnacka, Anna and Behera, B. and Beilicke, M. and Benbow, W. and Berger, K. and Bird, R. and B{\"o}ttcher, Markus and Bouvier, A. and Buchovecky, M. and Buckley, J. H. and Bugaev, V. and Cardenzana, J. V. and Cerruti, M. and Cesarini, A. and Chen, Xuhui and Ciupik, L. and Collins-Hughes, E. and Connolly, M. P. and Cui, W. and Dumm, J. and Eisch, J. D. and Falcone, A. and Federici, Simone and Feng, Q. and Finley, J. P. and Fleischhack, H. and Fortin, P. and Fortson, L. and Furniss, A. and Galante, N. and Gall, D. and Gillanders, G. H. and Griffin, S. and Griffiths, S. T. and Grube, J. and Gyuk, G. and H{\"u}tten, M. and Hakansson, Nils and Holder, J. and Hughes, G. and Humensky, T. B. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kelley-Hoskins, N. and Kertzman, M. and Khassen, Y. and Kieda, D. and Krause, M. and Krawczynski, H. and Krennrich, F. and Lang, M. J. and Madhavan, A. S. and Maier, G. and McArthur, S. and McCann, A. and Meagher, K. and Millis, J. and Moriarty, P. and Mukherjee, R. and Nieto, D. and Ong, R. A. and Orr, M. and Otte, A. N. and Pandel, D. and Park, N. and Pelassa, V. and Perkins, J. S. and Pichel, A. and Pohl, Martin and Popkow, A. and Quinn, J. and Ragan, K. and Reyes, L. C. and Reynolds, P. T. and Roache, E. and Rousselle, J. and Rovero, A. C. and Saxon, D. B. and Sembroski, G. H. and Shahinyan, K. and Sheidaei, F. and Skole, C. and Smith, A. W. and Staszak, D. and Telezhinsky, Igor O. and Theiling, M. and Todd, N. W. and Tucci, J. V. and Tyler, J. and Varlotta, A. and Vassiliev, V. V. and Vincent, S. and Wakely, S. P. and Weiner, O. M. and Weinstein, A. and Welsing, R. and Wilhelm, Alina and Williams, D. A. and Zitzer, B. and Baring, M. G. and Gonzalez, J. Becerra and Cillis, A. N. and Horan, D. and Paneque, D.},
  title     = {Very high energy outburst of Markarian 501 in May 2009},
  series = {Physical chemistry, chemical physics : a journal of European Chemical Societies},
  volume    = {594},
  journal   = {Physical chemistry, chemical physics : a journal of European Chemical Societies},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  organization    = {Veritas Collaboration},
  issn      = {1432-0746},
  doi       = {10.1051/0004-6361/201628744},
  pages     = {12},
  year      = {2016},
  abstract  = {The very high energy (VHE; E > 100 GeV) blazar Markarian 501 was observed between April 17 and May 5 (MJD 54 938-54 956), 2009, as part of an extensive multiwavelength campaign from radio to VHE. Strong VHE yray activity was detected on May 1st with Whipple and VERITAS, when the flux (E > 400 GeV) increased to 10 times the preflare baseline flux (3.9 x 10(-11) ph cm(-2) s(-1)), reaching five times the flux of the Crab Nebula. This coincided with a decrease in the optical polarization and a rotation of the polarization angle by 15. This VHE flare showed a fast flux variation with an increase of a factor similar to 4 in 25 min, and a falling time of similar to 50 min. We present the observations of the quiescent state previous to the flare and of the high state after the flare, focusing on the flux and spectral variability from Whipple, VERITAS, Fermi-LAT, RXTE, and Swift combined with optical and radio data.},
  language  = {en}
}
@article{ArchambaultArlenAuneetal.2014,
  author    = {Archambault, S. and Arlen, T. and Aune, T. and Beilicke, M. and Benbow, W. and Bird, R. and Boettcher, Markus and Bouvier, A. and Buckley, J. H. and Bugaev, V. and Ciupik, L. and Collins-Hughes, E. and Connolly, M. P. and Cui, W. and Dickherber, R. and Dumm, J. and Errando, M. and Falcone, A. and Federici, Simone and Feng, Q. and Finley, J. P. and Fortson, L. and Furniss, A. and Galante, N. and Gall, D. and Garson, A. III. and Gillanders, G. H. and Griffin, S. and Grube, J. and Gusbar, C. and Gyuk, G. and Hanna, D. and Holder, J. and Hughes, G. and Kaaret, P. and Kertzman, M. and Khassen, Y. and Kieda, D. and Krawczynski, H. and Lamerato, A. and Lang, M. J. and Li, K. and Madhavan, A. S. and Maier, G. and Majumdar, P. and McArthur, S. and McCann, A. and Millis, J. and Moriarty, P. and Mukherjee, R. and Nieto, D. and Ong, R. A. and Orr, M. and Otte, A. N. and Park, N. and Perkins, J. S. and Pohl, Martin and Popkow, A. and Prokoph, H. and Quinn, J. and Ragan, K. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Roustazadeh, P. and Saxon, D. B. and Sembroski, G. H. and Senturk, G. D. and Skole, C. and Staszak, D. and Telezhinsky, Igor O. and Tesic, G. and Theiling, M. and Varlotta, A. and Vassiliev, V. V. and Vincent, S. and Wakely, S. P. and Weinstein, A. and Welsing, R. and Williams, D. A. and Zitzer, B.},
  title     = {Test of models of the cosmic infrared background with multiwavelength observations of the blazar 1ES 1218+30.4 IN 2009},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {788},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.1088/0004-637X/788/2/158},
  pages     = {9},
  year      = {2014},
  abstract  = {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.},
  language  = {en}
}
@article{AliuArlenAuneetal.2011,
  author    = {Aliu, E. and Arlen, T. and Aune, T. and Beilicke, M. and Benbow, W. and Boettcher, Markus and Bouvier, A. and Bradbury, S. M. and Buckley, J. H. and Bugaev, V. and Cannon, A. and Cesarini, A. and Ciupik, L. and Collins-Hughes, E. and Connolly, M. P. and Cui, W. and Dickherber, R. and Errando, M. and Falcone, A. and Finley, J. P. and Fortson, L. and Furniss, A. and Galante, N. and Gall, D. and Gillanders, G. H. and Godambe, S. and Griffin, S. and Grube, J. and Gyuk, G. and Hanna, D. and Holder, J. and Huan, H. and Hughes, G. and Hui, C. M. and Humensky, T. B. and Kaaret, P. and Karlsson, N. and Kertzman, M. and Kieda, D. and Krawczynski, H. and Krennrich, F. and Madhavan, A. S. and Maier, G. and Majumdar, P. and McArthur, S. and McCann, A. and Moriarty, P. and Mukherjee, R. and Ong, R. A. and Orr, M. and Otte, A. N. and Park, N. and Perkins, J. S. and Pichel, A. and Pohl, Martin and Prokoph, H. and Quinn, J. and Ragan, K. and Reyes, L. C. and Reynolds, P. T. and Roache, E. and Rose, H. J. and Ruppel, J. and Saxon, D. B. and Schroedter, M. and Sembroski, G. H. and Skole, C. and Smith, A. W. and Staszak, D. and Tesic, G. and Theiling, M. and Thibadeau, S. and Tsurusaki, K. and Tyler, J. and Varlotta, A. and Vincent, S. and Vivier, M. and Wakely, S. P. and Ward, J. E. and Weinstein, A. and Weisgarber, T. and Williams, D. A.},
  title     = {Veritas observations of unusual extragalactic transient swift J164449.3+573451},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters},
  volume    = {738},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {2041-8205},
  doi       = {10.1088/2041-8205/738/2/L30},
  pages     = {5},
  year      = {2011},
  abstract  = {We report on very high energy (>100 GeV) gamma-ray observations of Swift J164449.3+573451, an unusual transient object first detected by the Swift Observatory and later detected by multiple radio, optical, and X-ray observatories. A total exposure of 28 hr was obtained on Swift J164449.3+573451 with the Very Energetic Radiation Imaging Telescope Array System ( VERITAS) during 2011 March 28-April 15. We do not detect the source and place a differential upper limit on the emission at 500 GeV during these observations of 1.4 x 10(-12) erg cm(-2) s(-1) (99\% confidence level). We also present time-resolved upper limits and use a flux limit averaged over the X-ray flaring period to constrain various emission scenarios that can accommodate both the radio-through-X-ray emission detected from the source and the lack of detection by VERITAS.},
  language  = {en}
}
@article{AliuAuneBeilickeetal.2011,
  author    = {Aliu, E. and Aune, T. and Beilicke, M. and Benbow, W. and Boettcher, Markus and Bouvier, A. and Bradbury, S. M. and Buckley, J. H. and Bugaev, V. and Cannon, A. and Cesarini, A. and Ciupik, L. and Connolly, M. P. and Cui, W. and Decerprit, G. and Dickherber, R. and Duke, C. and Errando, M. and Falcone, A. and Feng, Q. and Finnegan, G. and Fortson, L. and Furniss, A. and Galante, N. and Gall, D. and Gillanders, G. H. and Godambe, S. and Griffin, S. and Grube, J. and Gyuk, G. and Hanna, D. and Hivick, B. and Holder, J. and Huan, H. and Hughes, G. and Hui, C. M. and Humensky, T. B. and Kaaret, P. and Karlsson, N. and Kertzman, M. and Kieda, D. and Krawczynski, H. and Krennrich, F. and Maier, G. and Majumdar, P. and McArthur, S. and McCann, A. and Moriarty, P. and Mukherjee, R. and Nelson, T. and Ong, R. A. and Orr, M. and Otte, A. N. and Park, N. and Perkins, J. S. and Pichel, A. and Pohl, Martin and Prokoph, H. and Quinn, J. and Ragan, K. and Reyes, L. C. and Reynolds, P. T. and Roache, E. and Rose, H. J. and Ruppel, J. and Saxon, D. B. and Sembroski, G. H. and Skole, C. and Smith, A. W. and Staszak, D. and Tesic, G. and Theiling, M. and Thibadeau, S. and Tsurusaki, K. and Tyler, J. and Varlotta, A. and Vassiliev, V. V. and Wakely, S. P. and Weekes, T. C. and Weinstein, A. and Williams, D. A. and Zitzer, B. and Ciprini, S. and Fumagalli, M. and Kaplan, K. and Paneque, D. and Prochaska, J. X.},
  title     = {Multiwavelenght observations of the previously unidentified blzar RX J0648.7+1516},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {742},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  organization    = {VERITAS Collaboration},
  issn      = {0004-637X},
  doi       = {10.1088/0004-637X/742/2/127},
  pages     = {7},
  year      = {2011},
  abstract  = {We report on the VERITAS discovery of very high energy (VHE) gamma-ray emission above 200 GeV from the high-frequency-peaked BL Lac (HBL) object RX J0648.7+1516 (GB J0648+1516), associated with 1FGL J0648.8+1516. The photon spectrum above 200 GeV is fitted by a power law dN/dE = F-0(E/E-0)(-Gamma) with a photon index Gamma of 4.4 +/- 0.8(stat) +/- 0.3(syst) and a flux normalization F-0 of (2.3 +/- 0.5(stat) +/- 1.2(sys)) x 10(-11) TeV-1 cm(-2) s(-1) with E-0 = 300 GeV. No VHE variability is detected during VERITAS observations of RX J0648.7+1516 between 2010 March 4 and April 15. Following the VHE discovery, the optical identification and spectroscopic redshift were obtained using the Shane 3 m Telescope at the Lick Observatory, showing the unidentified object to be a BL Lac type with a redshift of z = 0.179. Broadband multiwavelength observations contemporaneous with the VERITAS exposure period can be used to subclassify the blazar as an HBL object, including data from the MDM observatory, Swift-UVOT, and X-Ray Telescope, and continuous monitoring at photon energies above 1 GeV from the Fermi Large Area Telescope (LAT). We find that in the absence of undetected, high-energy rapid variability, the one-zone synchrotron self-Compton (SSC) model overproduces the high-energy gamma-ray emission measured by the Fermi-LAT over 2.3 years. The spectral energy distribution can be parameterized satisfactorily with an external-Compton or lepto-hadronic model, which have two and six additional free parameters, respectively, compared to the one-zone SSC model.},
  language  = {en}
}
@article{AliuArlenAuneetal.2012,
  author    = {Aliu, E. and Arlen, T. and Aune, T. and Beilicke, M. and Benbow, W. and Bouvier, A. and Bradbury, S. M. and Buckley, J. H. and Bugaev, V. and Byrum, K. and Cannon, A. and Cesarini, A. and Ciupik, L. and Collins-Hughes, E. and Connolly, M. P. and Cui, W. and Dickherber, R. and Duke, C. and Errando, M. and Falcone, A. and Finley, J. P. and Finnegan, G. and Fortson, L. and Furniss, A. and Galante, N. and Gall, D. and Godambe, S. and Griffin, S. and Grube, J. and Guenette, R. and Gyuk, G. and Hanna, D. and Holder, J. and Huan, H. and Hughes, G. and Hui, C. M. and Humensky, T. B. and Imran, A. and Kaaret, P. and Karlsson, N. and Kertzman, M. and Kieda, D. and Krawczynski, H. and Krennrich, F. and Lang, M. J. and LeBohec, S. and Madhavan, A. S. and Maier, G. and Majumdar, P. and McArthur, S. and McCann, A. and Moriarty, P. and Mukherjee, R. and Nunez, P. D. and Ong, R. A. and Orr, M. and Otte, A. N. and Park, N. and Perkins, J. S. and Pichel, A. and Pohl, Martin and Prokoph, H. and Quinn, J. and Ragan, K. and Reyes, L. C. and Reynolds, P. T. and Roache, E. and Rose, H. J. and Ruppel, J. and Saxon, D. B. and Schroedter, M. and Sembroski, G. H. and Sentuerk, G. D. and Skole, C. and Staszak, D. and Tesic, G. and Theiling, M. and Thibadeau, S. and Tsurusaki, K. and Tyler, J. and Varlotta, A. and Vassiliev, V. V. and Vincent, S. and Vivier, M. and Wakely, S. P. and Ward, J. E. and Weekes, T. C. and Weinstein, A. and Weisgarber, T. and Williams, D. A. and Zitzer, B.},
  title     = {Veritas observations of day-scale flaring of M 87 in 2010 April},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {746},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.1088/0004-637X/746/2/141},
  pages     = {7},
  year      = {2012},
  abstract  = {VERITAS has been monitoring the very-high-energy (VHE; > 100 GeV) gamma-ray activity of the radio galaxy M87 since 2007. During 2008, flaring activity on a timescale of a few days was observed with a peak flux of (0.70 +/- 0.16) x 10(-11) cm(-2) s(-1) at energies above 350 GeV. In 2010 April, VERITAS detected a flare from M 87 with peak flux of (2.71 +/- 0.68) x 10(-11) cm(-2) s(-1) for E > 350 GeV. The source was observed for six consecutive nights during the flare, resulting in a total of 21 hr of good-quality data. The most rapid flux variation occurred on the trailing edge of the flare with an exponential flux decay time of 0.90(-0.15)(+0.22) days. The shortest detected exponential rise time is three times as long, at 2.87(+1.65)(-0.99) days. The quality of the data sample is such that spectral analysis can be performed for three periods: rising flux, peak flux, and falling flux. The spectra obtained are consistent with power-law forms. The spectral index at the peak of the flare is equal to 2.19 +/- 0.07. There is some indication that the spectrum is softer in the falling phase of the flare than the peak phase, with a confidence level corresponding to 3.6 standard deviations. We discuss the implications of these results for the acceleration and cooling rates of VHE electrons in M 87 and the constraints they provide on the physical size of the emitting region.},
  language  = {en}
}
@article{AliuArchambaultArlenetal.2013,
  author    = {Aliu, E. and Archambault, S. and Arlen, T. and Aune, T. and Beilicke, M. and Benbow, W. and Bird, R. and Boettcher, Markus and Bouvier, A. and Bugaev, V. and Byrum, K. and Cesarini, A. and Ciupik, L. and Collins-Hughes, E. and Connolly, M. P. and Cui, W. and Dickherber, R. and Duke, C. and Dumm, J. and Errando, M. and Falcone, A. and Federici, Simone and Feng, Q. and Finley, J. P. and Finnegan, G. and Fortson, L. and Furniss, A. and Galante, N. and Gall, D. and Gillanders, G. H. and Griffin, S. and Grube, J. and Gyuk, G. and Hanna, D. and Holder, J. and Hughes, G. and Humensky, T. B. and Kaaret, P. and Kertzman, M. and Khassen, Y. and Kieda, D. and Krawczynski, H. and Krennrich, F. and Lang, M. J. and Madhavan, A. S. and Maier, G. and Majumdar, P. and McArthur, S. and McCann, A. and Moriarty, P. and Mukherjee, R. and Nelson, T. and de Bhroithe, A. O'Faolain and Ong, R. A. and Orr, M. and Otte, A. N. and Park, N. and Perkins, J. S. and Pichel, A. and Pohl, Martin and Popkow, A. and Prokoph, H. and Quinn, J. and Ragan, K. and Reyes, L. C. and Reynolds, P. T. and Roache, E. and Saxon, D. B. and Schroedter, M. and Sembroski, G. H. and Skole, C. and Smith, A. W. and Staszak, D. and Telezhinsky, Igor O. and Theiling, M. and Tyler, J. and Varlotta, A. and Vassiliev, V. V. and Wakely, S. P. and Weekes, T. C. and Weinstein, A. and Welsing, R. and Williams, D. A. and Zitzer, B.},
  title     = {Multiwavelenght observations and modeling of 1ES 1959+650 in a low flux state},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {775},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {1},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.1088/0004-637X/775/1/3},
  pages     = {8},
  year      = {2013},
  abstract  = {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.},
  language  = {en}
}