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Investigating broadband variability of the TeV blazar 1ES 1959+650.

Aliu, E. and Archambault, S. and Arlen, T. and Aune, T. and Barnacka, A. and Beilicke, M. and Benbow, W. and Berger, K. and Bird, R. and Bouvier, A. and Buckley, J.H. and Bugaev, V. and Cerruti, M. and Chen, X. 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, S. and Feng, Q. and Finley, J.P. and Fleischhack, H. and Fortin, P. and Fortson, L. and Furniss, A. and Galante, N. and Gillanders, G.H. and Griffin, S. and Griffiths, S.T. and Grube, J. and Gyuk, G. and Håkansson, N. and Hanna, D. and Holder, J. and Hughes, G. and Hughes, Z. and Humensky, T.B. and Johnson, C.A. and Kaaret, P. and Kar, 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 Majumdar, P. and McArthur, S. and McCann, A. and Meagher, K. and Millis, J. and Moriarty, P. and Mukherjee, R. and Nelson, T. and Nieto, D. and O'Faoláin de Bhróithe, A. and Ong, R.A. and Otte, A.N. and Park, N. and Perkins, J.S. and Pohl, M. and Popkow, A. and Prokoph, H. and Quinn, J. and Ragan, K. and Rajotte, J. and Reyes, L.C. and Reynolds, P.T. and Richards, G.T. and Roache, E. and Sadun, A. and Santander, M. and Sembroski, G.H. and Shahinyan, K. and Sheidaei, F. and Smith, A.W. and Staszak, D. and Telezhinsky, I. and Theiling, M. and Tyler, J. and Varlotta, A. and Vassiliev, V.V. and Vincent, S. and Wakely, S.P. and Weekes, T.C. and Weinstein, A. and Welsing, R. and Wilhelm, A. and Williams, D.A. and Zitzer, B. and Böttcher, M. and Fumagalli, M. (2014) 'Investigating broadband variability of the TeV blazar 1ES 1959+650.', Astrophysical journal., 797 (2).

Abstract

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.

Item Type:Article
Keywords:BL Lacertae objects: individual (1ES 1959+650), Gamma rays: galaxies.
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Status:Peer-reviewed
Publisher Web site:http://dx.doi.org/10.1088/0004-637X/797/2/89
Publisher statement:© 2014. The American Astronomical Society. All rights reserved. Printed in the U.S.A.
Date accepted:No date available
Date deposited:03 February 2015
Date of first online publication:December 2014
Date first made open access:No date available

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