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Aliu, E. ; Archambault, S. ; Arlen, T. ; Aune, T. ; Beilicke, M. ; Benbow, W. ; Bouvier, A. ; Bradbury, S. M. ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cannon, A. ; Cesarini, A. ; Christiansen, J. L. ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Cui, W. ; Decerprit, G. ; Dickherber, R. ; Dumm, J. ; Errando, M. ; Falcone, A. ; Feng, Q. ; Ferrer, F. ; Finley, J. P. ; Finnegan, G. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gall, D. ; Godambe, S. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Holder, J. ; Huan, H. ; Hughes, G. ; Humensky, T. B. ; Kaaret, P. ; Karlsson, N. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lee, K. ; Madhavan, A. S. ; Maier, G. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; Moriarty, P. ; Mukherjee, R. ; Ong, R. A. ; Orr, M. ; Otte, A. N. ; Park, N. ; Perkins, J. S. ; Pohl, Martin ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Roache, E. ; Rose, H. J. ; Ruppel, J. ; Saxon, D. B. ; Schroedter, M. ; Sembroski, G. H. ; Sentuerk, G. D. ; Skole, C. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Tesic, G. ; Theiling, M. ; Thibadeau, S. ; Tsurusaki, K. ; Varlotta, A. ; Vassiliev, V. V. ; Vincent, S. ; Vivier, M. ; Wagner, R. G. ; Wakely, S. P. ; Ward, J. E. ; Weekes, T. C. ; Weinstein, A. ; Weisgarber, T. ; Williams, D. A. ; Zitzer, B.
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 <sigma upsilon >(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.
Multiwavelength observations of the AGN 1ES 0414+009 with veritas, FERMI-LAT, SWIFT-XRT, AND MDM
(2012)
Aliu, E. ; Archambault, S. ; Arlen, T. ; Aune, T. ; Beilicke, M. ; Benbow, W. ; Boettcher, Markus ; Bouvier, A. ; Bugaev, V. ; Cannon, A. ; Cesarini, A. ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Cui, W. ; Dickherber, R. ; Dumm, J. ; Errando, M. ; Falcone, A. ; Federici, Stefania ; Feng, Q. ; Finley, J. P. ; Finnegan, G. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gall, D. ; Godambe, S. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Holder, J. ; Huan, H. ; Hughes, G. ; Hui, C. M. ; Imran, A. ; Jameil, O. ; Kaaret, P. ; Karlsson, N. ; Kertzman, M. ; Kerr, J. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Lee, K. ; Madhavan, A. S. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; Moriarty, P. ; Mukherjee, R. ; Nelson, T. ; de Bhroithe, A. O'Faolain ; Ong, R. A. ; Orr, M. ; Otte, A. N. ; Park, N. ; Perkins, J. S. ; Pichel, A. ; Pohl, Martin ; Quinn, J. ; Ragan, K. ; Reynolds, P. T. ; Roache, E. ; Ruppel, J. ; Saxon, D. B. ; Schroedter, M. ; Sembroski, G. H. ; Sentuerk, G. D. ; Smith, A. W. ; Staszak, D. ; Stroh, M. ; Telezhinsky, Igor O. ; Tesic, G. ; Theiling, M. ; Thibadeau, S. ; Tsurusaki, K. ; Varlotta, A. ; Vassiliev, V. V. ; Vivier, M. ; Wakely, S. P. ; Ward, J. E. ; Weinstein, A. ; Welsing, R. ; Williams, D. A. ; Zitzer, B.
We present observations of the BL Lac object 1ES 0414+009 in the >200 GeV gamma-ray band by the VERITAS array of Cherenkov telescopes. 1ES 0414+009 was observed by VERITAS between 2008 January and 2011 February, resulting in 56.2 hr of good quality pointed observations. These observations resulted in a detection of 822 events from the source corresponding to a statistical significance of 6.4 standard deviations (6.4 sigma) above the background. The source flux, showing no evidence for variability, is measured as (5.2 +/- 1.1(stat) +/- 2.6(sys)) x 10(-12) photons cm(-2) s(-1) above 200 GeV, equivalent to approximately 2% of the Crab Nebula flux above this energy. The differential photon spectrum from 230 GeV to 850 GeV is well fit by a power law with a photon index of Gamma = 3.4 +/- 0.5(stat) +/- 0.3(sys) and a flux normalization of (1.6 +/- 0.3(stat) +/- 0.8(sys)) x 10(-11) photons cm(-2) s(-1) at 300 GeV. We also present multiwavelength results taken in the optical (MDM), x-ray (Swift-XRT), and GeV (Fermi-LAT) bands and use these results to construct a broadband spectral energy distribution (SED). Modeling of this SED indicates that homogenous one-zone leptonic scenarios are not adequate to describe emission from the system, with a lepto-hadronic model providing a better fit to the data.
Aliu, E. ; Archambault, S. ; Arlen, T. ; Aune, T. ; Beilicke, M. ; Benbow, W. ; Boettcher, Markus ; Bouvier, A. ; Buckley, J. H. ; Bugaev, V. ; Cesarini, A. ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Cui, W. ; Dickherber, R. ; Duke, C. ; Dumm, J. ; Errando, M. ; Falcone, A. ; Federici, Simone ; Feng, Q. ; Finley, J. P. ; Finnegan, G. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gall, D. ; Godambe, S. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Holder, J. ; Huan, H. ; Kaaret, P. ; Karlsson, N. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lee, K. ; Madhavan, A. S. ; Maier, G. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; Moriarty, P. ; Mukherjee, R. ; Nelson, T. ; de Bhroithe, A. O'Faolain ; Ong, R. A. ; Orr, M. ; Otte, A. N. ; Park, N. ; Perkins, J. S. ; Pichel, A. ; Pohl, Martin ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Roache, E. ; Saxon, D. B. ; Sembroski, G. H. ; Staszak, D. ; Telezhinsky, Igor O. ; Tesic, G. ; Theiling, M. ; Thibadeau, S. ; Tsurusaki, K. ; Varlotta, A. ; Vassiliev, V. V. ; Vincent, S. ; Vivier, M. ; Wakely, S. P. ; Weekes, T. C. ; Weinstein, A. ; Welsing, R. ; Williams, D. A. ; Zitzer, B. ; Fortin, P. ; Horan, D. ; Fumagalli, M. ; Kaplan, K. ; Prochaska, J. X.
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.
Aliu, E. ; Archambault, S. ; Arlen, T. ; Aune, T. ; Beilicke, M. ; Benbow, W. ; Boettcher, Markus ; Bouvier, A. ; Bradbury, S. M. ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cannon, A. ; Cesarini, A. ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Coppi, P. ; Cui, W. ; Decerprit, G. ; Dickherber, R. ; Dumm, J. ; Errando, Manel ; Falcone, A. ; Feng, Q. ; Finley, J. P. ; Finnegan, G. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gall, D. ; Godambe, S. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Hawkins, K. ; Holder, J. ; Huan, H. ; Hughes, G. ; Humensky, T. B. ; Kaaret, P. ; Karlsson, N. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Lee, K. ; Madhavan, A. S. ; Maier, G. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; Moriarty, P. ; Mukherjee, Reshmi ; Ong, R. A. ; Orr, M. ; Otte, A. N. ; Palma, N. ; Park, N. ; Perkins, J. S. ; Pichel, A. ; Pohl, Martin ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Roache, E. ; Rose, H. J. ; Ruppel, J. ; Saxon, D. B. ; Schroedter, M. ; Sembroski, G. H. ; Sentuerk, G. D. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Tesic, G. ; Theiling, M. ; Thibadeau, S. ; Tsurusaki, K. ; Varlotta, A. ; Vivier, M. ; Wakely, S. P. ; Ward, J. E. ; Weekes, T. C. ; Weinstein, A. ; Weisgarber, T. ; Williams, D. A. ; Zitzer, B. ; Fortin, P. ; Horan, D.
We report on the discovery of high-energy (HE; E > 0.1 GeV) and very high energy (VHE; E > 100 GeV) gamma-ray emission from the high-frequency-peaked BL Lac object RBS 0413. VERITAS, a ground-based gamma-ray observatory, detected VHE. rays from RBS 0413 with a statistical significance of 5.5 standard deviations (sigma) and a gamma-ray flux of (1.5 +/- 0.6(stat) +/- 0.7(syst)) x 10(-8) photons m(-2) s(-1) (similar to 1% of the Crab Nebula flux) above 250 GeV. The observed spectrum can be described by a power law with a photon index of 3.18 +/- 0.68(stat) +/- 0.30(syst). Contemporaneous observations with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope detected HE gamma rays from RBS 0413 with a (stat)istical significance of more than 9 sigma, a power-law photon index of 1.57 +/- 0.12(stat-0.12sys')(+0.11) and a gamma-ray flux between 300 MeV and 300 GeV of (1.64 +/- 0.43(stat-0.22sys)(+ 0.31)) x 10(-5) photons m(-2) s(-1). We present the results from Fermi-LAT and VERITAS, including a spectral energy distribution modeling of the gamma-ray, quasi-simultaneous X-ray (Swift-XRT), ultraviolet (Swift-UVOT), and R-band optical (MDM) data. We find that, if conditions close to equipartition are required, both the combined synchrotron self-Compton/external-Compton and the lepto-hadronic models are preferred over a pure synchrotron self-Compton model.
Aliu, E. ; Archambault, S. ; Arlen, T. ; Aune, T. ; Beilicke, M. ; Benbow, W. ; Bird, R. ; Bouvier, A. ; Buckley, J. H. ; Bugaev, V. ; Cesarini, A. ; Ciupik, L. ; Connolly, M. P. ; Cui, W. ; Dumm, J. ; Errando, M. ; Falcone, A. ; Federici, Simone ; Feng, Q. ; Finley, J. P. ; Fortin, P. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gerard, L. ; Gillanders, G. H. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Kaaret, P. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Madhavan, A. S. ; Maier, G. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; De Bhroithe, A. O'Faolain ; Ong, R. A. ; Orr, M. ; Otte, A. N. ; Park, N. ; Perkins, J. S. ; Pohl, Martin ; Popkow, A. ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Saxon, D. B. ; Sembroski, G. H. ; Skole, C. ; Smith, A. W. ; Soares-Furtado, M. ; Staszak, D. ; Telezhinsky, Igor O. ; Tesic, G. ; Theiling, M. ; Varlotta, A. ; Vassiliev, V. V. ; Vincent, S. ; Wakely, S. P. ; Weekes, T. C. ; Weinstein, A. ; Welsing, R. ; Williams, D. A. ; Zitzer, B. ; Böttcher, Markus ; Fumagalli, M. ; Jadhav, J.
We report on VERITAS observations of the BL Lac object B2 1215+30 between 2008 and 2012. During this period, the source was detected at very high energies (VHEs; E > 100 GeV) by VERITAS with a significance of 8.9s and showed clear variability on timescales larger than months. In 2011, the source was found to be in a relatively bright state and a power-law fit to the differential photon spectrum yields a spectral index of 3.6 +/- 0.4(stat) +/- 0.3(syst) with an integral flux above 200 GeV of (8.0 +/- 0.9(stat) +/- 3.2(syst)) x 10(-12) cm(-2) s(-1). No short term variability could be detected during the bright state in 2011. Multi-wavelength data were obtained contemporaneously with the VERITAS observations in 2011 and cover optical (Super-LOTIS, MDM, Swift/UVOT), X-ray (Swift/XRT), and gamma-ray (Fermi-LAT) frequencies. These were used to construct the spectral energy distribution (SED) of B2 1215+30. A one-zone leptonic model is used to model the blazar emission and the results are compared to those of MAGIC from early 2011 and other VERITAS-detected blazars. The SED can be reproduced well with model parameters typical for VHE-detected BL Lac objects.
Aliu, E. ; Archambault, S. ; Arlen, T. ; Aune, T. ; Beilicke, M. ; Benbow, W. ; Bird, R. ; Boettcher, Markus ; Bouvier, A. ; Bugaev, V. ; Byrum, K. ; Cesarini, A. ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Cui, W. ; Dickherber, R. ; Duke, C. ; Dumm, J. ; Errando, M. ; Falcone, A. ; Federici, Simone ; Feng, Q. ; Finley, J. P. ; Finnegan, G. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gall, D. ; Gillanders, G. H. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Kaaret, P. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Madhavan, A. S. ; Maier, G. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; Moriarty, P. ; Mukherjee, R. ; Nelson, T. ; de Bhroithe, A. O'Faolain ; Ong, R. A. ; Orr, M. ; Otte, A. N. ; Park, N. ; Perkins, J. S. ; Pichel, A. ; Pohl, Martin ; Popkow, A. ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Roache, E. ; Saxon, D. B. ; Schroedter, M. ; Sembroski, G. H. ; Skole, C. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Theiling, M. ; Tyler, J. ; Varlotta, A. ; Vassiliev, V. V. ; Wakely, S. P. ; Weekes, T. C. ; Weinstein, A. ; Welsing, R. ; Williams, D. A. ; Zitzer, B.
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.
Aliu, E. ; Archambault, S. ; Arlen, T. ; Aune, T. ; Behera, B. ; Beilicke, M. ; Benbow, W. ; Berger, K. ; Bird, R. ; Bouvier, A. ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cerruti, M. ; Chen, Xuhui ; Ciupik, L. ; Connolly, M. P. ; Cui, W. ; Duke, C. ; Dumm, J. ; Errando, M. ; Falcone, A. ; Federici, S. ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Fortin, P. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gillanders, G. H. ; Griffin, S. ; Griffiths, S. T. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Johnson, C. A. ; Kaaret, P. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Madhavan, A. S. ; Maier, G. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; Meagher, K. ; Millis, J. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Perkins, J. S. ; Pohl, M. ; Popkow, A. ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Sembroski, G. H. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Theiling, M. ; Varlotta, A. ; Vassiliev, V. V. ; Vincent, S. ; Wakely, S. P. ; Weekes, T. C. ; Weinstein, A. ; Welsing, R. ; Williams, D. A. ; Zajczyk, A. ; Zitzer, B.
Aliu, E. ; Archambault, S. ; Arlen, T. ; Aune, T. ; Barnacka, Anna ; Beilicke, M. ; Benbow, W. ; Berger, K. ; Bird, R. ; Bouvier, A. ; Buckley, J. H. ; Bugaev, V. ; Cerruti, M. ; Chen, X. ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Cui, W. ; Dumm, J. ; Eisch, J. D. ; Falcone, A. ; Federici, S. ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Fortin, P. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gillanders, G. H. ; Griffin, S. ; Griffiths, S. T. ; Grube, J. ; Gyuk, G. ; Hakansson, N. ; Hanna, D. ; Holder, J. ; Hughes, G. ; Hughes, Z. ; Humensky, T. B. ; Johnson, C. A. ; Kaaret, P. ; Kar, P. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Madhavan, A. S. ; Majumdar, P. ; McArthur, S. ; McCann, A. ; Meagher, K. ; Millis, J. ; Moriarty, P. ; Mukherjee, R. ; Nelson, T. ; Nieto, D. ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Perkins, J. S. ; Pohl, M. ; Popkow, A. ; Prokoph, H. ; Quinn, J. ; Ragan, K. ; Rajotte, J. ; Reyes, L. C. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Sadun, A. ; Santander, M. ; Sembroski, G. H. ; Shahinyan, K. ; Sheidaei, F. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Theiling, M. ; Tyler, J. ; Varlotta, A. ; Vassiliev, V. V. ; Vincent, S. ; Wakely, S. P. ; Weekes, T. C. ; Weinstein, A. ; Welsing, R. ; Wilhelm, Alina ; Williams, D. A. ; Zitzer, B. ; Boettcher, Markus ; Fumagalli, M.
We summarize broadband observations of the TeV-emitting blazar 1ES 1959+650, including optical R-band observations by the robotic telescopes Super-LOTIS and iTelescope, UV observations by Swift Ultraviolet and Optical Telescope, X-ray observations by the Swift X-ray Telescope, high-energy gamma-ray observations with the Fermi Large Area Telescope, and very-high-energy (VHE) gamma-ray observations by VERITAS above 315 GeV, all taken between 2012 April 17 and 2012 June 1 (MJD 56034 and 56079). The contemporaneous variability of the broadband spectral energy distribution is explored in the context of a simple synchrotron self Compton (SSC) model. In the SSC emission scenario, we find that the parameters required to represent the high state are significantly different than those in the low state. Motivated by possible evidence of gas in the vicinity of the blazar, we also investigate a reflected emission model to describe the observed variability pattern. This model assumes that the non-thermal emission from the jet is reflected by a nearby cloud of gas, allowing the reflected emission to re-enter the blob and produce an elevated gamma-ray state with no simultaneous elevated synchrotron flux. The model applied here, although not required to explain the observed variability pattern, represents one possible scenario which can describe the observations. As applied to an elevated VHE state of 66% of the Crab Nebula flux, observed on a single night during the observation period, the reflected emission scenario does not support a purely leptonic non-thermal emission mechanism. The reflected emission model does, however, predict a reflected photon field with sufficient energy to enable elevated gamma-ray emission via pion production with protons of energies between 10 and 100 TeV.
Aliu, E. ; Archambault, S. ; Archer, A. ; Aune, T. ; Barnacka, Anna ; Beilicke, M. ; Benbow, W. ; Bird, R. ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cardenzana, J. V. ; Cerruti, M. ; Chen, Xuhui ; Ciupik, L. ; Connolly, M. P. ; Cui, W. ; Dickinson, H. J. ; Dumm, J. ; Eisch, J. D. ; Errando, M. ; Falcone, A. ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Fortin, P. ; Fortson, L. ; Furniss, A. ; Gillanders, G. H. ; Griffin, S. ; Griffiths, S. T. ; Grube, J. ; Gyuk, G. ; Kansson, N. H. A. ; Hanna, D. ; Holder, J. ; Humensky, T. B. ; Johnson, C. A. ; Kaaret, P. ; Kar, P. ; Kertzman, M. ; Kieda, D. ; Krennrich, F. ; Kumar, S. ; Lang, M. J. ; Lyutikov, M. ; Madhavan, A. S. ; Maier, G. ; McArthur, S. ; McCann, A. ; Meagher, K. ; Millis, J. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Pohl, Manuela ; Popkow, A. ; Prokoph, H. ; Pueschel, Elisa ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Santander, M. ; Sembroski, G. H. ; Shahinyan, K. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Tucci, J. V. ; Tyler, J. ; Varlotta, A. ; Vincent, S. ; Wakely, S. P. ; Weinstein, A. ; Williams, D. A. ; Zajczyk, A. ; Zitzer, B.
We present the results of 71.6 hr of observations of the Geminga pulsar (PSR J0633+1746) with the VERITAS very-high-energy gamma-ray telescope array. Data taken with VERITAS between 2007 November and 2013 February were phase-folded using a Geminga pulsar timing solution derived from data recorded by the XMM-Newton and Fermi-LAT space telescopes. No significant pulsed emission above 100 GeV is observed, and we report upper limits at the 95% confidence level on the integral flux above 135 GeV (spectral analysis threshold) of 4.0x10(-13) s(-1) cm(-2) and 1.7 x 10(-13) s(-1) cm(-2) for the two principal peaks in the emission profile. These upper limits, placed in context with phase-resolved spectral energy distributions determined from 5 yr of data from the Fermi-Large Area Telescope (LAT), constrain possible hardening of the Geminga pulsar emission spectra above similar to 50 GeV.
Aliu, E. ; Archambault, S. ; Archer, A. ; Arlen, T. ; Aune, T. ; Barnacka, Anna ; Behera, B. ; Beilicke, M. ; Benbow, W. ; Berger, K. ; Bird, R. ; Böttcher, Markus ; Bouvier, A. ; Buchovecky, M. ; Buckley, J. H. ; Bugaev, V. ; Cardenzana, J. V. ; Cerruti, M. ; Cesarini, A. ; Chen, Xuhui ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Cui, W. ; Dumm, J. ; Eisch, J. D. ; Falcone, A. ; Federici, Simone ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Fortin, P. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gall, D. ; Gillanders, G. H. ; Griffin, S. ; Griffiths, S. T. ; Grube, J. ; Gyuk, G. ; Hütten, M. ; Hakansson, Nils ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Johnson, C. A. ; Kaaret, P. ; Kar, P. ; Kelley-Hoskins, N. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krause, M. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Madhavan, A. S. ; Maier, G. ; McArthur, S. ; McCann, A. ; Meagher, K. ; Millis, J. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Ong, R. A. ; Orr, M. ; Otte, A. N. ; Pandel, D. ; Park, N. ; Pelassa, V. ; Perkins, J. S. ; Pichel, A. ; Pohl, Martin ; Popkow, A. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Roache, E. ; Rousselle, J. ; Rovero, A. C. ; Saxon, D. B. ; Sembroski, G. H. ; Shahinyan, K. ; Sheidaei, F. ; Skole, C. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Theiling, M. ; Todd, N. W. ; Tucci, J. V. ; Tyler, J. ; Varlotta, A. ; Vassiliev, V. V. ; Vincent, S. ; Wakely, S. P. ; Weiner, O. M. ; Weinstein, A. ; Welsing, R. ; Wilhelm, Alina ; Williams, D. A. ; Zitzer, B. ; Baring, M. G. ; Gonzalez, J. Becerra ; Cillis, A. N. ; Horan, D. ; Paneque, D.
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.
Aleksic, J. ; Ansoldi, S. ; Antonelli, L. A. ; Antoranz, P. ; Babic, A. ; Bangale, P. ; de Almeida, U. Barres ; Barrio, J. A. ; Gonzalez, J. Becerra ; Bednarek, W. ; Berger, K. ; Bernardini, E. ; Bilandli, A. ; Bianch, O. ; Bock, R. K. ; Bonnefoy, S. ; Bonnoli, G. ; Borracci, F. ; Bretz, T. ; Carmona, E. ; Carosi, A. ; Fidalgo, D. Carreto ; Colin, P. ; Colombo, E. ; Contreras, J. L. ; Cortina, J. ; Covino, S. ; Da Vela, P. ; Dazzi, F. ; De Angelis, A. ; De Caneva, G. ; De Lotto, B. ; Delgado Mendez, C. ; Doert, M. ; Dominguez, A. ; Prester, Dijana Dominis ; Dorner, D. ; Doro, M. ; Einecke, S. ; Eisenacher, D. ; Elsaesser, D. ; Farina, E. ; Ferenc, D. ; Fonseca, M. V. ; Font, L. ; Frantzen, K. ; Fruck, C. ; Garcia Lopez, R. J. ; Garczarczyki, M. ; Garrido Terrats, D. ; Gaug, M. ; Giavitto, G. ; Godinovic, N. ; Gonzalez Munoz, A. ; Gozzini, S. R. ; Hadamek, A. ; Hadasch, D. ; Herrero, A. ; Hildebrand, D. ; Hose, J. ; Hrupec, D. ; Idec, W. ; Kadenius, V. ; Kellermann, H. ; Knoetig, M. L. ; Krause, J. ; Kushida, J. ; La Barbera, A. ; Lelas, D. ; Lewandowska, N. ; Lindfors, E. ; Longo, F. ; Lombardi, S. ; Lopez, M. ; Lopez-Coto, R. ; Lopez-Oramas, A. ; Lorenz, E. ; Lozano, I. ; Makariev, M. ; Mallot, K. ; Maneva, G. ; Mankuzhiyil, N. ; Mannheim, K. ; Maraschi, L. ; Marcote, B. ; Mariotti, M. ; Martinez, M. ; Mazin, D. ; Menzel, U. ; Meucci, M. ; Miranda, J. M. ; Mirzoyan, R. ; Moralejo, A. ; Munar-Adrover, P. ; Nakajima, D. ; Niedzwiecki, A. ; Nilsson, K. ; Nowak, N. ; Orito, R. ; Overkemping, A. ; Paiano, S. ; Palatiello, M. ; Paneque, D. ; Paoletti, R. ; Paredes, J. M. ; Paredes-Fortuny, X. ; Partini, S. ; Persic, M. ; Prada, F. ; Moroni, P. G. Prada ; Prandini, E. ; Preziuso, S. ; Puljak, I. ; Reinthal, R. ; Rhode, W. ; Ribo, M. ; Rico, J. ; Garcia, J. Rodriguez ; Ruegamer, S. ; Saggion, A. ; Saito, K. ; Salvati, M. ; Satalecka, K. ; Scalzotto, V. ; Scapin, V. ; Schuliz, C. ; Schweizer, T. ; Shore, S. N. ; Sillanpaa, A. ; Sitarek, J. ; Snidaric, I. ; Sobczynska, D. ; Spanier, F. ; Stamatescu, V. ; Stamerra, A. ; Steinbring, T. ; Storz, J. ; Sun, S. ; Suric, T. ; Takalo, L. ; Tavecchio, F. ; Temnikov, P. ; Terzic, T. ; Tescaro, D. ; Teshima, M. ; Thaele, J. ; Tibolla, O. ; Torres, D. F. ; Toyama, T. ; Treves, A. ; Uellenbeck, M. ; Vogler, P. ; Wagner, R. M. ; Zandanel, F. ; Zanin, R. ; Archambault, S. ; Behera, B. ; Beilicke, M. ; Benbow, W. ; Bird, R. ; Buckley, J. H. ; Bugaev, V. ; Cerruti, M. ; Chen, X. ; Ciupik, L. ; Collins-Hughes, E. ; Cui, W. ; Dumm, J. ; Eisch, J. D. ; Falcone, A. ; Federici, S. ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Fortin, P. ; Fortson, L. ; Furniss, A. ; Griffin, S. ; Griffiths, S. T. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Holder, J. ; Hughes, G. ; Humensky, T. B. ; Johnson, C. A. ; Kaaret, P. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Kumar, S. ; Lang, M. J. ; Maier, G. ; McArthur, S. ; Meagher, K. ; Moriarty, P. ; Mukherjee, R. ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Pichel, A. ; Pohl, M. ; Popkow, A. ; Prokoph, H. ; Quinn, M. J. ; Ragan, K. ; Rajotte, J. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Rovero, A. C. ; Sembroski, G. H. ; Shahinyan, K. ; Staszak, D. ; Telezhinsky, Igor O. ; Theiling, M. ; Tucci, J. V. ; Tyler, J. ; Varlotta, A. ; Wakely, S. P. ; Weekes, T. C. ; Weinstein, A. ; Welsing, R. ; Wilhelm, Alina ; Williams, D. A. ; Zitzer, B. ; Villata, M. ; Raiteri, C. ; Aller, H. D. ; Aller, M. F. ; Chen, W. P. ; Jordan, B. ; Koptelova, E. ; Kurtanidze, O. M. ; Lahteenmaki, A. ; McBreen, B. ; Larionov, V. M. ; Lin, C. S. ; Nikolashvili, M. G. ; Angelakis, E. ; Capalbi, M. ; Carraminana, A. ; Carrasco, L. ; Cassaro, P. ; Cesarini, A. ; Fuhrmann, L. ; Giroletti, M. ; Hovatta, T. ; Krichbaum, T. P. ; Krimm, H. A. ; Max-Moerbeck, W. ; Moody, J. W. ; Maccaferri, G. ; Mori, Y. ; Nestoras, I. ; Orlati, A. ; Pace, C. ; Pearson, R. ; Perri, M. ; Readhead, A. C. S. ; Richards, J. L. ; Sadun, A. C. ; Sakamoto, T. ; Tammi, J. ; Tornikoski, M. ; Yatsu, Y. ; Zook, A.
Aims. We perform an extensive characterization of the broadband emission of Mrk 421, as well as its temporal evolution, during the non-flaring (low) state. The high brightness and nearby location (z = 0.031) of Mrk 421 make it an excellent laboratory to study blazar emission. The goal is to learn about the physical processes responsible for the typical emission of Mrk 421, which might also be extended to other blazars that are located farther away and hence are more difficult to study.
Methods. We performed a 4.5-month multi-instrument campaign on Mrk 421 between January 2009 and June 2009, which included VLBA, F-GAMMA, GASP-WEBT, Swift, RXTE, Fermi-LAT, MAGIC, and Whipple, among other instruments and collaborations. This extensive radio to very-high-energy (VHE; E > 100 GeV) gamma-ray dataset provides excellent temporal and energy coverage, which allows detailed studies of the evolution of the broadband spectral energy distribution.
Results. Mrk421 was found in its typical (non-flaring) activity state, with a VHE flux of about half that of the Crab Nebula, yet the light curves show significant variability at all wavelengths, the highest variability being in the X-rays. We determined the power spectral densities (PSD) at most wavelengths and found that all PSDs can be described by power-laws without a break, and with indices consistent with pink/red-noise behavior. We observed a harder-when-brighter behavior in the X-ray spectra and measured a positive correlation between VHE and X-ray fluxes with zero time lag. Such characteristics have been reported many times during flaring activity, but here they are reported for the first time in the non-flaring state. We also observed an overall anti-correlation between optical /UV and X-rays extending over the duration of the campaign.
Conclusions. The harder-when-brighter behavior in the X-ray spectra and the measured positive X-ray/VHE correlation during the 2009 multiwavelength campaign suggests that the physical processes dominating the emission during non-flaring states have similarities with those occurring during flaring activity. In particular, this observation supports leptonic scenarios as being responsible for the emission of Mrk 421 during non-flaring activity. Such a temporally extended X-ray /VHE correlation is not driven by any single flaring event, and hence is difficult to explain within the standard hadronic scenarios. The highest variability is observed in the X-ray band, which, within the one-zone synchrotron self-Compton scenario, indicates that the electron energy distribution is most variable at the highest energies.
Aleksic, J. ; Ansoldi, S. ; Antonelli, L. A. ; Antoranz, P. ; Babic, A. ; Bangale, P. ; de Almeida, U. Barres ; Barrio, J. A. ; Becerra Gonzalez, J. ; Bednarek, W. ; Berger, K. ; Bernardini, E. ; Biland, A. ; Blanch Bigas, O. ; Bock, R. K. ; Bonnefoy, S. ; Bonnoli, G. ; Borracci, F. ; Bretz, T. ; Carmona, E. ; Carosi, A. ; Fidalgo, D. Carreto ; Colin, P. ; Colombo, E. ; Contreras, J. L. ; Cortina, J. ; Covino, S. ; Da Vela, P. ; Dazzi, F. ; De Angelis, A. ; De Caneva, G. ; De Lotto, B. ; Delgado Mendez, C. ; Doert, M. ; Dominguez, A. ; Prester, Dijana Dominis ; Dorner, D. ; Doro, M. ; Einecke, S. ; Eisenacher, D. ; Elsaesser, D. ; Farina, E. ; Ferenc, D. ; Fonseca, M. V. ; Font, L. ; Frantzen, K. ; Fruck, C. ; Garcia Lopez, R. J. ; Garczarczyk, M. ; Garrido Terrats, D. ; Gaug, M. ; Giavitto, G. ; Godinovic, N. ; Gonzalez Munoz, A. ; Gozzini, S. R. ; Hadamek, A. ; Hadasch, D. ; Herrero, A. ; Hildebrand, D. ; Hose, J. ; Hrupec, D. ; Idec, W. ; Kadenius, V. ; Kellermann, H. ; Knoetig, M. L. ; Krause, J. ; Kushida, J. ; La Barbera, A. ; Lelas, D. ; Lewandowska, N. ; Lindfors, E. ; Lombardi, S. ; Lopez, M. ; Lopez-Coto, R. ; Lopez-Oramas, A. ; Lorenz, E. ; Lozano, I. ; Makariev, M. ; Mallot, K. ; Maneva, G. ; Mankuzhiyil, N. ; Mannheim, K. ; Maraschi, L. ; Marcote, B. ; Mariotti, M. ; Martinez, M. ; Mazin, D. ; Menzel, U. ; Meucci, M. ; Miranda, J. M. ; Mirzoyan, R. ; Moralejo, A. ; Munar-Adrover, P. ; Nakajima, D. ; Niedzwiecki, A. ; Nilsson, K. ; Nowak, N. ; Orito, R. ; Overkemping, A. ; Paiano, S. ; Palatiello, M. ; Paneque, D. ; Paoletti, R. ; Paredes, J. M. ; Paredes-Fortuny, X. ; Partini, S. ; Persic, M. ; Prada, F. ; Moroni, P. G. Prada ; Prandini, E. ; Preziuso, S. ; Puljak, I. ; Reinthal, R. ; Rhode, W. ; Ribo, M. ; Rico, J. ; Garcia, J. Rodriguez ; Ruegamer, S. ; Saggion, A. ; Saito, T. ; Saito, K. ; Salvati, M. ; Satalecka, K. ; Scalzotto, V. ; Scapin, V. ; Schultz, C. ; Schweizer, T. ; Shore, S. N. ; Sillanpaa, A. ; Sitarek, J. ; Snidaric, I. ; Sobczynska, D. ; Spanier, F. ; Stamatescu, V. ; Stamerra, A. ; Steinbring, T. ; Storz, J. ; Sun, S. ; Suric, T. ; Takalo, L. ; Tavecchio, F. ; Temnikov, P. ; Terzic, T. ; Tescaro, D. ; Teshima, M. ; Thaele, J. ; Tibolla, O. ; Torres, D. F. ; Toyama, T. ; Treves, A. ; Uellenbeck, M. ; Vogler, P. ; Wagner, R. M. ; Zandanel, F. ; Zanin, R. ; Behera, B. ; Beilicke, M. ; Benbow, W. ; Berger, K. ; Bird, R. ; Bouvier, A. ; Bugaev, V. ; Cerruti, M. ; Chen, Xuhui ; Ciupik, L. ; Collins-Hughes, E. ; Cui, W. ; Duke, C. ; Dumm, J. ; Falcone, A. ; Federici, Simone ; Feng, Q. ; Finley, J. P. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gillanders, G. H. ; Griffin, S. ; Griffiths, S. T. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Holder, J. ; Johnson, C. A. ; Kaaret, P. ; Kertzman, M. ; Kieda, D. ; Krawczynski, H. ; Lang, M. J. ; Madhavan, A. S. ; Maier, G. ; Majumdar, P. ; Meagher, K. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Ong, R. A. ; Otte, A. N. ; Pichel, A. ; Pohl, Manula ; Popkow, A. ; Prokoph, H. ; Quinn, J. ; Rajotte, J. ; Ratliff, G. ; Reyes, L. C. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Sembroski, G. H. ; Shahinyan, K. ; Sheidaei, F. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Theiling, M. ; Tyler, J. ; Varlotta, A. ; Vincent, S. ; Wakely, S. P. ; Weekes, T. C. ; Welsing, R. ; Williams, D. A. ; Zajczyk, A. ; Zitzer, B. ; Villata, M. ; Raiteri, C. M. ; Ajello, M. ; Perri, M. ; Aller, H. D. ; Aller, M. F. ; Larionov, V. M. ; Efimova, N. V. ; Konstantinova, T. S. ; Kopatskaya, E. N. ; Chen, W. P. ; Koptelova, E. ; Hsiao, H. Y. ; Kurtanidze, O. M. ; Nikolashvili, M. G. ; Kimeridze, G. N. ; Jordan, B. ; Leto, Paolo ; Buemi, C. S. ; Trigilio, C. ; Umana, G. ; Lahteenmaki, A. ; Nieppola, E. ; Tornikoski, M. ; Sainio, J. ; Kadenius, V. ; Giroletti, M. ; Cesarini, A. ; Fuhrmann, L. ; Kovalev, Yu. A. ; Kovalev, Y. Y.
Context. Blazars are variable sources on various timescales over a broad energy range spanning from radio to very high energy (>100 GeV, hereafter VHE). Mrk 501 is one of the brightest blazars at TeV energies and has been extensively studied since its first VHE detection in 1996. However, most of the gamma-ray studies performed on Mrk 501 during the past years relate to flaring activity, when the source detection and characterization with the available gamma-ray instrumentation was easier to perform.
Aims. Our goal is to characterize the source gamma-ray emission in detail, together with the radio-to-X-ray emission, during the non-flaring (low) activity, which is less often studied than the occasional flaring (high) activity.
Methods. We organized a multiwavelength (MW) campaign on Mrk 501 between March and May 2008. This multi-instrument effort included the most sensitive VHE gamma-ray instruments in the northern hemisphere, namely the imaging atmospheric Cherenkov telescopes MAGIC and VERITAS, as well as Swift, RXTE, the F-GAMMA, GASP-WEBT, and other collaborations and instruments. This provided extensive energy and temporal coverage of Mrk 501 throughout the entire campaign.
Results. Mrk 501 was found to be in a low state of activity during the campaign, with a VHE flux in the range of 10%-20% of the Crab nebula flux. Nevertheless, significant flux variations were detected with various instruments, with a trend of increasing variability with energy and a tentative correlation between the X-ray and VHE fluxes. The broadband spectral energy distribution during the two different emission states of the campaign can be adequately described within the homogeneous one-zone synchrotron self-Compton model, with the (slightly) higher state described by an increase in the electron number density.
Conclusions. The one-zone SSC model can adequately describe the broadband spectral energy distribution of the source during the two months covered by the MW campaign. This agrees with previous studies of the broadband emission of this source during flaring and non-flaring states. We report for the first time a tentative X-ray-to-VHE correlation during such a low VHE activity. Although marginally significant, this positive correlation between X-ray and VHE, which has been reported many times during flaring activity, suggests that the mechanisms that dominate the X-ray/VHE emission during non-flaring-activity are not substantially different from those that are responsible for the emission during flaring activity.
Introducing the CTA concept
(2013)
Acharya, B. S. ; Actis, M. ; Aghajani, T. ; Agnetta, G. ; Aguilar, J. ; Aharonian, Felix A. ; Ajello, M. ; Akhperjanian, A. G. ; Alcubierre, M. ; Aleksic, J. ; Alfaro, R. ; Aliu, E. ; Allafort, A. J. ; Allan, D. ; Allekotte, I. ; Amato, E. ; Anderson, J. ; Angüner, Ekrem Oǧuzhan ; Antonelli, L. A. ; Antoranz, P. ; Aravantinos, A. ; Arlen, T. ; Armstrong, T. ; Arnaldi, H. ; Arrabito, L. ; Asano, K. ; Ashton, T. ; Asorey, H. G. ; Awane, Y. ; Baba, H. ; Babic, A. ; Baby, N. ; Baehr, J. ; Bais, A. ; Baixeras, C. ; Bajtlik, S. ; Balbo, M. ; Balis, D. ; Balkowski, C. ; Bamba, A. ; Bandiera, R. ; Barber, A. ; Barbier, C. ; Barcelo, M. ; Barnacka, Anna ; Barnstedt, Jürgen ; Barres de Almeida, U. ; Barrio, J. A. ; Basili, A. ; Basso, S. ; Bastieri, D. ; Bauer, C. ; Baushev, Anton N. ; Becerra Gonzalez, J. ; Becherini, Yvonne ; Bechtol, K. C. ; Tjus, J. Becker ; Beckmann, Volker ; Bednarek, W. ; Behera, B. ; Belluso, M. ; Benbow, W. ; Berdugo, J. ; Berger, K. ; Bernard, F. ; Bernardino, T. ; Bernlöhr, K. ; Bhat, N. ; Bhattacharyya, S. ; Bigongiari, C. ; Biland, A. ; Billotta, S. ; Bird, T. ; Birsin, E. ; Bissaldi, E. ; Biteau, Jonathan ; Bitossi, M. ; Blake, S. ; Blanch Bigas, O. ; Blasi, P. ; Bobkov, A. A. ; Boccone, V. ; Boettcher, Markus ; Bogacz, L. ; Bogart, J. ; Bogdan, M. ; Boisson, Catherine ; Boix Gargallo, J. ; Bolmont, J. ; Bonanno, G. ; Bonardi, A. ; Bonev, T. ; Bonifacio, P. ; Bonnoli, G. ; Bordas, Pol ; Borgland, A. W. ; Borkowski, Janett ; Bose, R. ; Botner, O. ; Bottani, A. ; Bouchet, L. ; Bourgeat, M. ; Boutonnet, C. ; Bouvier, A. ; Brau-Nogue, S. ; Braun, I. ; Bretz, T. ; Briggs, M. S. ; Bringmann, T. ; Brook, P. ; Brun, Pierre ; Brunetti, L. ; Buanes, T. ; Buckley, J. H. ; Buehler, R. ; Bugaev, V. ; Bulgarelli, A. ; Bulik, Tomasz ; Busetto, G. ; Buson, S. ; Byrum, K. ; Cailles, M. ; Cameron, R. A. ; Camprecios, J. ; Canestrari, R. ; Cantu, S. ; Capalbi, M. ; Caraveo, P. A. ; Carmona, E. ; Carosi, A. ; Carr, John ; Carton, P. H. ; Casanova, Sabrina ; Casiraghi, M. ; Catalano, O. ; Cavazzani, S. ; Cazaux, S. ; Cerruti, M. ; Chabanne, E. ; Chadwick, Paula M. ; Champion, C. ; Chen, Andrew ; Chiang, J. ; Chiappetti, L. ; Chikawa, M. ; Chitnis, V. R. ; Chollet, F. ; Chudoba, J. ; Cieslar, M. ; Cillis, A. N. ; Cohen-Tanugi, J. ; Colafrancesco, Sergio ; Colin, P. ; Calome, J. ; Colonges, S. ; Compin, M. ; Conconi, P. ; Conforti, V. ; Connaughton, V. ; Conrad, Jan ; Contreras, J. L. ; Coppi, P. ; Corona, P. ; Corti, D. ; Cortina, J. ; Cossio, L. ; Costantini, H. ; Cotter, G. ; Courty, B. ; Couturier, S. ; Covino, S. ; Crimi, G. ; Criswell, S. J. ; Croston, J. ; Cusumano, G. ; Dafonseca, M. ; Dale, O. ; Daniel, M. ; Darling, J. ; Davids, I. ; Dazzi, F. ; De Angelis, A. ; De Caprio, V. ; De Frondat, F. ; de Gouveia Dal Pino, E. M. ; de la Calle, I. ; De La Vega, G. A. ; Lopez, R. de los Reyes ; De Lotto, B. ; De Luca, A. ; de Mello Neto, J. R. T. ; de Naurois, M. ; de Oliveira, Y. ; de Ona Wilhelmi, E. ; de Souza, V. ; Decerprit, G. ; Decock, G. ; Deil, C. ; Delagnes, E. ; Deleglise, G. ; Delgado, C. ; Della Volpe, D. ; Demange, P. ; Depaola, G. ; Dettlaff, A. ; Di Paola, A. ; Di Pierro, F. ; Diaz, C. ; Dick, J. ; Dickherber, R. ; Dickinson, H. ; Diez-Blanco, V. ; Digel, S. ; Dimitrov, D. ; Disset, G. ; Djannati-Ataï, A. ; Doert, M. ; Dohmke, M. ; Domainko, W. ; Prester, Dijana Dominis ; Donat, A. ; Dorner, D. ; Doro, M. ; Dournaux, J-L. ; Drake, G. ; Dravins, D. ; Drury, L. ; Dubois, F. ; Dubois, R. ; Dubus, G. ; Dufour, C. ; Dumas, D. ; Dumm, J. ; Durand, D. ; Dyks, J. ; Dyrda, M. ; Ebr, J. ; Edy, E. ; Egberts, Kathrin ; Eger, P. ; Einecke, S. ; Eleftheriadis, C. ; Elles, S. ; Emmanoulopoulos, D. ; Engelhaupt, D. ; Enomoto, R. ; Ernenwein, J-P ; Errando, M. ; Etchegoyen, A. ; Evans, P. ; Falcone, A. ; Fantinel, D. ; Farakos, K. ; Farnier, C. ; Fasola, G. ; Favill, B. ; Fede, E. ; Federici, S. ; Fegan, S. ; Feinstein, F. ; Ferenc, D. ; Ferrando, P. ; Fesquet, M. ; Fiasson, A. ; Fillin-Martino, E. ; Fink, D. ; Finley, C. ; Finley, J. P. ; Fiorini, M. ; Firpo Curcoll, R. ; Flores, H. ; Florin, D. ; Focke, W. ; Foehr, C. ; Fokitis, E. ; Font, L. ; Fontaine, G. ; Fornasa, M. ; Foerster, A. ; Fortson, L. ; Fouque, N. ; Franckowiak, A. ; Fransson, C. ; Fraser, G. ; Frei, R. ; Albuquerque, I. F. M. ; Fresnillo, L. ; Fruck, C. ; Fujita, Y. ; Fukazawa, Y. ; Fukui, Y. ; Funk, S. ; Gaebele, W. ; Gabici, S. ; Gabriele, R. ; Gadola, A. ; Galante, N. ; Gall, D. ; Gallant, Y. ; Gamez-Garcia, J. ; Garcia, B. ; Garcia Lopez, R. ; Gardiol, D. ; Garrido, D. ; Garrido, L. ; Gascon, D. ; Gaug, M. ; Gaweda, J. ; Gebremedhin, L. ; Geffroy, N. ; Gerard, L. ; Ghedina, A. ; Ghigo, M. ; Giannakaki, E. ; Gianotti, F. ; Giarrusso, S. ; Giavitto, G. ; Giebels, B. ; Gika, V. ; Giommi, P. ; Girard, N. ; Giro, E. ; Giuliani, A. ; Glanzman, T. ; Glicenstein, J. -F. ; Godinovic, N. ; Golev, V. ; Gomez Berisso, M. ; Gomez-Ortega, J. ; Gonzalez, M. M. ; Gonzalez, A. ; Gonzalez, F. ; Gonzalez Munoz, A. ; Gothe, K. S. ; Gougerot, M. ; Graciani, R. ; Grandi, P. ; Granena, F. ; Granot, J. ; Grasseau, G. ; Gredig, R. ; Green, A. ; Greenshaw, T. ; Gregoire, T. ; Grimm, O. ; Grube, J. ; Grudzinska, M. ; Gruev, V. ; Gruenewald, S. ; Grygorczuk, J. ; Guarino, V. ; Gunji, S. ; Gyuk, G. ; Hadasch, D. ; Hagiwara, R. ; Hahn, J. ; Hakansson, N. ; Hallgren, A. ; Hamer Heras, N. ; Hara, S. ; Hardcastle, M. J. ; Harris, J. ; Hassan, T. ; Hatanaka, K. ; Haubold, T. ; Haupt, A. ; Hayakawa, T. ; Hayashida, M. ; Heller, R. ; Henault, F. ; Henri, G. ; Hermann, G. ; Hermel, R. ; Herrero, A. ; Hidaka, N. ; Hinton, J. ; Hoffmann, D. ; Hofmann, W. ; Hofverberg, P. ; Holder, J. ; Horns, D. ; Horville, D. ; Houles, J. ; Hrabovsky, M. ; Hrupec, D. ; Huan, H. ; Huber, B. ; Huet, J. -M. ; Hughes, G. ; Humensky, T. B. ; Huovelin, J. ; Ibarra, A. ; Illa, J. 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B. ; Kifune, T. ; Kihm, T. ; Kishimoto, T. ; Kitamoto, K. ; Kluzniak, W. ; Knapic, C. ; Knapp, J. w ; Knoedlseder, J. ; Koeck, F. ; Kocot, J. ; Kodani, K. ; Koehne, J. -H. ; Kohri, K. ; Kokkotas, K. ; Kolitzus, D. ; Komin, N. ; Kominis, I. ; Konno, Y. ; Koeppel, H. ; Korohoda, P. ; Kosack, K. ; Koss, G. ; Kossakowski, R. ; Kostka, P. ; Koul, R. ; Kowal, G. ; Koyama, S. ; Koziol, J. ; Kraehenbuehl, T. ; Krause, J. ; Krawzcynski, H. ; Krennrich, F. ; Krepps, A. ; Kretzschmann, A. ; Krobot, R. ; Krueger, P. ; Kubo, H. ; Kudryavtsev, V. A. ; Kushida, J. ; Kuznetsov, A. ; La Barbera, A. ; La Palombara, N. ; La Parola, V. ; La Rosa, G. ; Lacombe, K. ; Lamanna, G. ; Lande, J. ; Languignon, D. ; Lapington, J. ; Laporte, P. ; Lavalley, C. ; Le Flour, T. ; Le Padellec, A. ; Lee, S. -H. ; Lee, W. H. ; Leigui de Oliveira, M. A. ; Lelas, D. ; Lenain, J. -P. ; Leopold, D. 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M. ; Madhavan, A. ; Mahabir, M. ; Maier, G. ; Majumdar, P. ; Malaguti, G. ; Maltezos, S. ; Manalaysay, A. ; Mancilla, A. ; Mandat, D. ; Maneva, G. ; Mangano, A. ; Manigot, P. ; Mannheim, K. ; Manthos, I. ; Maragos, N. ; Marcowith, Alexandre ; Mariotti, M. ; Marisaldi, M. ; Markoff, S. ; Marszalek, A. ; Martens, C. ; Marti, J. ; Martin, J-M. ; Martin, P. ; Martinez, G. ; Martinez, F. ; Martinez, M. ; Masserot, A. ; Mastichiadis, A. ; Mathieu, A. ; Matsumoto, H. ; Mattana, F. ; Mattiazzo, S. ; Maurin, G. ; Maxfield, S. ; Maya, J. ; Mazin, D. ; Mc Comb, L. ; McCubbin, N. ; McHardy, I. ; McKay, R. ; Medina, C. ; Melioli, C. ; Melkumyan, D. ; Mereghetti, S. ; Mertsch, P. ; Meucci, M. ; Michalowski, J. ; Micolon, P. ; Mihailidis, A. ; Mineo, T. ; Minuti, M. ; Mirabal, N. ; Mirabel, F. ; Miranda, J. M. ; Mirzoyan, R. ; Mizuno, T. ; Moal, B. ; Moderski, R. ; Mognet, I. ; Molinari, E. ; Molinaro, M. ; Montaruli, T. ; Monteiro, I. ; Moore, P. ; Moralejo Olaizola, A. ; Mordalska, M. ; Morello, C. ; Mori, K. ; Mottez, F. ; Moudden, Y. ; Moulin, Emmanuel ; Mrusek, I. ; Mukherjee, R. ; Munar-Adrover, P. ; Muraishi, H. ; Murase, K. ; Murphy, A. ; Nagataki, S. ; Naito, T. ; Nakajima, D. ; Nakamori, T. ; Nakayama, K. ; Naumann, C. L. ; Naumann, D. ; Naumann-Godo, M. ; Nayman, P. ; Nedbal, D. ; Neise, D. ; Nellen, L. ; Neustroev, V. ; Neyroud, N. ; Nicastro, L. ; Nicolau-Kuklinski, J. ; Niedzwiecki, A. ; Niemiec, J. ; Nieto, D. ; Nikolaidis, A. ; Nishijima, K. ; Nolan, S. ; Northrop, R. ; Nosek, D. ; Nowak, N. ; Nozato, A. ; O'Brien, P. ; Ohira, Y. ; Ohishi, M. ; Ohm, S. ; Ohoka, H. ; Okuda, T. ; Okumura, A. ; Olive, J. -F. ; Ong, R. A. ; Orito, R. ; Orr, M. ; Osborne, J. ; Ostrowski, M. ; Otero, L. A. ; Otte, N. ; Ovcharov, E. ; Oya, I. ; Ozieblo, A. ; Padilla, L. ; Paiano, S. ; Paillot, D. ; Paizis, A. ; Palanque, S. ; Palatka, M. ; Pallota, J. ; Panagiotidis, K. ; Panazol, J. -L. ; Paneque, D. ; Panter, M. ; Paoletti, R. ; Papayannis, Alexandros ; Papyan, G. ; Paredes, J. M. ; Pareschi, G. ; Parks, G. ; Parraud, J. -M. ; Parsons, D. ; Arribas, M. Paz ; Pech, M. ; Pedaletti, G. ; Pelassa, V. ; Pelat, D. ; Perez, M. D. C. ; Persic, M. ; Petrucci, P-O ; Peyaud, B. ; Pichel, A. ; Pita, S. ; Pizzolato, F. ; Platos, L. ; Platzer, R. ; Pogosyan, L. ; Pohl, M. ; Pojmanski, G. ; Ponz, J. D. ; Potter, W. ; Poutanen, J. ; Prandini, E. ; Prast, J. ; Preece, R. ; Profeti, F. ; Prokoph, H. ; Prouza, M. ; Proyetti, M. ; Puerto-Gimenez, I. ; Puehlhofer, G. ; Puljak, I. ; Punch, M. ; Pyziol, R. ; Quel, E. J. ; Quinn, J. ; Quirrenbach, A. ; Racero, E. ; Rajda, P. J. ; Ramon, P. ; Rando, R. ; Rannot, R. C. ; Rataj, M. ; Raue, M. ; Reardon, P. ; Reimann, O. ; Reimer, A. ; Reimer, O. ; Reitberger, K. ; Renaud, M. ; Renner, S. ; Reville, B. ; Rhode, W. ; Ribo, M. ; Ribordy, M. ; Richer, M. G. ; Rico, J. ; Ridky, J. ; Rieger, F. ; Ringegni, P. ; Ripken, J. ; Ristori, P. R. ; Riviere, A. ; Rivoire, S. ; Rob, L. ; Roeser, U. ; Rohlfs, R. ; Rojas, G. ; Romano, Patrizia ; Romaszkan, W. ; Romero, G. E. ; Rosen, S. ; Lees, S. Rosier ; Ross, D. ; Rouaix, G. ; Rousselle, J. ; Rousselle, S. ; Rovero, A. C. ; Roy, F. ; Royer, S. ; Rudak, B. ; Rulten, C. ; Rupinski, M. ; Russo, F. ; Ryde, F. ; Sacco, B. ; Saemann, E. O. ; Saggion, A. ; Safiakian, V. ; Saito, K. ; Saito, T. ; Saito, Y. ; Sakaki, N. ; Sakonaka, R. ; Salini, A. ; Sanchez, F. ; Sanchez-Conde, M. ; Sandoval, A. ; Sandaker, H. ; Sant'Ambrogio, E. ; Santangelo, Andrea ; Santos, E. M. ; Sanuy, A. ; Sapozhnikov, L. ; Sarkar, S. ; Sartore, N. ; Sasaki, H. ; Satalecka, K. ; Sawada, M. ; Scalzotto, V. ; Scapin, V. ; Scarcioffolo, M. ; Schafer, J. ; Schanz, T. ; Schlenstedt, S. ; Schlickeiser, R. ; Schmidt, T. ; Schmoll, J. ; Schovanek, P. ; Schroedter, M. ; Schultz, C. ; Schultze, J. ; Schulz, A. ; Schure, K. ; Schwab, T. ; Schwanke, U. ; Schwarz, J. ; Schwarzburg, S. ; Schweizer, T. ; Schwemmer, S. ; Segreto, A. ; Seiradakis, J. -H. ; Sembroski, G. H. ; Seweryn, K. ; Sharma, M. ; Shayduk, M. ; Shellard, R. C. ; Shi, J. ; Shibata, T. ; Shibuya, A. ; Shum, E. ; Sidoli, L. ; Sidz, M. ; Sieiro, J. ; Sikora, M. ; Silk, J. ; Sillanpaa, A. ; Singh, B. B. ; Sitarek, J. ; Skole, C. ; Smareglia, R. ; Smith, A. ; Smith, D. ; Smith, J. ; Smith, N. ; Sobczynska, D. ; Sol, H. ; Sottile, G. ; Sowinski, M. ; Spanier, F. ; Spiga, D. ; Spyrou, S. ; Stamatescu, V. ; Stamerra, A. ; Starling, R. ; Stawarz, L. ; Steenkamp, R. ; Stegmann, Christian ; Steiner, S. ; Stergioulas, N. ; Sternberger, R. ; Sterzel, M. ; Stinzing, F. ; Stodulski, M. ; Straumann, U. ; Strazzeri, E. ; Stringhetti, L. ; Suarez, A. ; Suchenek, M. ; Sugawara, R. ; Sulanke, K. -H. ; Sun, S. ; Supanitsky, A. D. ; Suric, T. ; Sutcliffe, P. ; Sykes, J. ; Szanecki, M. ; Szepieniec, T. ; Szostek, A. ; Tagliaferri, G. ; Tajima, H. ; Takahashi, H. ; Takahashi, K. ; Takalo, L. ; Takami, H. ; Talbot, C. ; Tammi, J. ; Tanaka, M. ; Tanaka, S. ; Tasan, J. ; Tavani, M. ; Tavernet, J. -P. ; Tejedor, L. A. ; Telezhinsky, Igor O. ; Temnikov, P. ; Tenzer, C. ; Terada, Y. ; Terrier, R. ; Teshima, M. ; Testa, V. ; Tezier, D. ; Thuermann, D. ; Tibaldo, L. ; Tibolla, O. ; Tiengo, A. ; Tluczykont, M. ; Todero Peixoto, C. J. ; Tokanai, F. ; Tokarz, M. ; Toma, K. ; Torii, K. ; Tornikoski, M. ; Torres, D. F. ; Torres, M. ; Tosti, G. ; Totani, T. ; Toussenel, C. ; Tovmassian, G. ; Travnicek, P. ; Trifoglio, M. ; Troyano, I. ; Tsinganos, K. ; Ueno, H. ; Umehara, K. ; Upadhya, S. S. ; Usher, T. ; Uslenghi, M. ; Valdes-Galicia, J. F. ; Vallania, P. ; Vallejo, G. ; van Driel, W. ; van Eldik, C. ; Vandenbrouke, J. ; Vanderwalt, J. ; Vankov, H. ; Vasileiadis, G. ; Vassiliev, V. ; Veberic, D. ; Vegas, I. ; Vercellone, S. ; Vergani, S. ; Veyssiere, C. ; Vialle, J. P. ; Viana, A. ; Videla, M. ; Vincent, P. ; Vincent, S. ; Vink, J. ; Vlahakis, N. ; Vlahos, L. ; Vogler, P. ; Vollhardt, A. ; von Gunten, H. P. ; Vorobiov, S. ; Vuerli, C. ; Waegebaert, V. ; Wagner, R. ; Wagner, R. G. ; Wagner, S. ; Wakely, S. P. ; Walter, R. ; Walther, T. ; Warda, K. ; Warwick, R. ; Wawer, P. ; Wawrzaszek, R. ; Webb, N. ; Wegner, P. ; Weinstein, A. ; Weitzel, Q. ; Welsing, R. ; Werner, M. ; Wetteskind, H. ; White, R. ; Wierzcholska, A. ; Wiesand, S. ; Wilkinson, M. ; Williams, D. A. ; Willingale, R. ; Winiarski, K. ; Wischnewski, R. ; Wisniewski, L. ; Wood, M. ; Woernlein, A. ; Xiong, Q. ; Yadav, K. K. ; Yamamoto, H. ; Yamamoto, T. ; Yamazaki, R. ; Yanagita, S. ; Yebras, J. M. ; Yelos, D. ; Yoshida, A. ; Yoshida, T. ; Yoshikoshi, T. ; Zabalza, V. ; Zacharias, M. ; Zajczyk, A. ; Zanin, R. ; Zdziarski, A. ; Zech, Alraune ; Zhao, A. ; Zhou, X. ; Zietara, K. ; Ziolkowski, J. ; Ziolkowski, P. ; Zitelli, V. ; Zurbach, C. ; Zychowski, P.
The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project.
Acciari, V. A. ; Arlen, T. ; Aune, T. ; Benbow, W. ; Bird, R. ; Bouvier, A. ; Bradbury, S. M. ; Buckley, J. H. ; Bugaev, V. ; de la Calle Perez, I. ; Carter-Lewis, D. A. ; Cesarini, A. ; Ciupik, L. ; Collins-Hughes, E. ; Connolly, M. P. ; Cui, W. ; Duke, C. ; Dumm, J. ; Falcone, A. ; Federici, Simone ; Fegan, D. J. ; Fegan, S. J. ; Finley, J. P. ; Finnegan, G. ; Fortson, L. ; Gaidos, J. ; Galante, N. ; Gall, D. ; Gibbs, K. ; Gillanders, G. H. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Hanna, D. ; Horan, D. ; Humensky, T. B. ; Kaaret, P. ; Kertzman, M. ; Khassen, Y. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; McEnery, J. E. ; Madhavan, A. S. ; Moriarty, P. ; Nelson, T. ; Ong, R. A. ; Orr, M. ; Otte, A. N. ; Perkins, J. S. ; Petry, D. ; Pichel, A. ; Pohl, M. ; Quinn, J. ; Ragan, K. ; Reynolds, T. ; Roache, E. ; Rovero, A. ; Schroedter, M. ; Sembroski, G. H. ; Smith, A. ; Telezhinsky, Igor O. ; Theiling, M. ; Toner, J. ; Tyler, J. ; Varlotta, A. ; Vivier, M. ; Wakely, S. P. ; Ward, J. E. ; Weekes, T. C. ; Weinstein, A. ; Welsing, R. ; Williams, D. A. ; Wissel, S.
The variability of the blazar Markarian 421 in TeV gamma rays over a 14-year time period has been explored with the Whipple 10 m telescope. It is shown that the dynamic range of its flux variations is large and similar to that in X-rays. A correlation between the X-ray and TeV energy bands is observed during some bright flares and when the complete data sets are binned on long timescales. The main database consists of 878.4 h of observation with the Whipple telescope, spread over 783 nights. The peak energy response of the telescope was 400 GeV with 20% uncertainty. This is the largest database of any TeV-emitting active galactic nucleus (AGN) and hence was used to explore the variability profile of Markarian 421. The tithe-averaged flux from Markarian 421 over this period was 0.446 +/- 0.008 Crab flux units. The flux exceeded 10 Crab flux units on three separate occasions. For the 2000-2001 season the average flux reached 1.86 Crab units, while in the 1996-1997 season the average flux was only 0.23 Crab units.
Abeysekara, A. U. ; Archambault, S. ; Archer, A. ; Benbow, W. ; Bird, R. ; Biteau, Jonathan ; Buchovecky, M. ; Buckley, J. H. ; Bugaev, V. ; Byrum, K. ; Cardenzana, J. V. ; Cerruti, M. ; Chen, Xuhui ; Christiansen, J. L. ; Ciupik, L. ; Connolly, M. P. ; Cui, W. ; Dickinson, H. J. ; Dumm, J. ; Eisch, J. D. ; Errando, M. ; Falcone, A. ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Flinders, A. ; Fortin, P. ; Fortson, L. ; Furniss, A. ; Gillanders, G. H. ; Griffin, S. ; Grube, J. ; Gyuk, G. ; Huetten, M. ; Hanna, D. ; Holder, J. ; Humensky, T. B. ; Johnson, C. A. ; Kaaret, P. ; Kar, P. ; Kelley-Hoskins, N. ; Kertzman, M. ; Kieda, D. ; Krause, M. ; Krennrich, F. ; Lang, M. J. ; Maier, G. ; McArthur, S. ; McCann, A. ; Meagher, K. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Pelassa, V. ; Petrashyk, A. ; Petry, D. ; Pohl, Martin ; Popkow, A. ; Pueschel, Elisa ; Quinn, J. ; Ragan, K. ; Ratliff, G. ; Reyes, L. C. ; Reynolds, P. T. ; Reynolds, K. ; Richards, G. T. ; Roache, E. ; Rulten, C. ; Santander, M. ; Sembroski, G. H. ; Shahinyan, K. ; Smith, A. W. ; Staszak, D. ; Telezhinsky, Igor O. ; Tucci, J. V. ; Tyler, J. ; Vincent, S. ; Wakely, S. P. ; Weiner, O. M. ; Weinstein, A. ; Wilhelm, Alina ; Williams, D. A. ; Zitzer, B.
We present results from multiwavelength observations of the BL Lacertae object 1ES 1741 + 196, including results in the very high energy gamma-ray regime using the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The VERITAS time-averaged spectrum, measured above 180 GeV, is well modelled by a power law with a spectral index of 2.7 +/- 0.7(stat) +/- 0.2(syst). The integral flux above 180 GeV is (3.9 +/- 0.8(stat) +/- 1.0(syst)) x 10(-8) m(-2) s(-1), corresponding to 1.6 per cent of the Crab nebula flux on average. The multiwavelength spectral energy distribution of the source suggests that 1ES 1741+196 is an extreme-high-frequency-peaked BL Lacertae object. The observations analysed in this paper extend over a period of six years, during which time no strong flares were observed in any band. This analysis is therefore one of the few characterizations of a blazar in a non-flaring state.