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Title: MULTIWAVELENGTH OBSERVATIONS AND MODELING OF 1ES 1959+650 IN A LOW FLUX STATE

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 {approx}< 2 in the high energy (E > 1 MeV) and very high energy (E > 100 GeV) {gamma}-ray regimes, which is corroboratedmore » by the Fermi-LAT, VERITAS, and Whipple 10 m telescope light curves.« less
Authors:
;  [1] ;  [2] ; ;  [3] ; ; ;  [4] ;  [5] ; ;  [6] ;  [7] ;  [8] ;  [9] ; ;  [10] ;  [11] ;  [12] ;  [13] ;  [14] more »; « less
  1. Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States)
  2. Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada)
  3. Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)
  4. Department of Physics, Washington University, St. Louis, MO 63130 (United States)
  5. Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States)
  6. School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)
  7. Astrophysical Institute, Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States)
  8. Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States)
  9. Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)
  10. School of Physics, National University of Ireland Galway, University Road, Galway (Ireland)
  11. Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States)
  12. Department of Physics, Purdue University, West Lafayette, IN 47907 (United States)
  13. Department of Physics, Grinnell College, Grinnell, IA 50112-1690 (United States)
  14. School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)
Publication Date:
OSTI Identifier:
22133848
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 775; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BL LACERTAE OBJECTS; ELECTRON BEAM INJECTION; EMISSION; ENERGY SPECTRA; GAMMA RADIATION; GEV RANGE; LUMINOSITY; MEV RANGE; SIMULATION; TELESCOPES; TEV RANGE; VISIBLE RADIATION; X RADIATION; X-RAY SPECTRA