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Title: Extreme blazars studied with Fermi-lat and Suzaku: 1ES 0347–121 and blazar candidate HESS J1943+213

We report on our study of high-energy properties of two peculiar TeV emitters: the 'extreme blazar' 1ES 0347–121 and the 'extreme blazar candidate' HESS J1943+213 located near the Galactic plane. Both objects are characterized by quiescent synchrotron emission with flat spectra extending up to the hard X-ray range, and both were reported to be missing GeV counterparts in the Fermi Large Area Telescope (LAT) two-year Source Catalog. We analyze a 4.5 yr accumulation of the Fermi-LAT data, resulting in the detection of 1ES 0347–121 in the GeV band, as well as in improved upper limits for HESS J1943+213. We also present the analysis results of newly acquired Suzaku data for HESS J1943+213. The X-ray spectrum is well represented by a single power law extending up to 25 keV with photon index 2.00 ± 0.02 and a moderate absorption in excess of the Galactic value, which is in agreement with previous X-ray observations. No short-term X-ray variability was found over the 80 ks duration of the Suzaku exposure. Under the blazar hypothesis, we modeled the spectral energy distributions of 1ES 0347–121 and HESS J1943+213, and we derived constraints on the intergalactic magnetic field strength and source energetics. We conclude that althoughmore » the classification of HESS J1943+213 has not yet been determined, the blazar hypothesis remains the most plausible option since, in particular, the broadband spectra of the two analyzed sources along with the source model parameters closely resemble each other, and the newly available Wide-field Infrared Survey Explorer and UKIRT Infrared Deep Sky Survey data for HESS J1943+213 are consistent with the presence of an elliptical host at the distance of approximately ∼600 Mpc.« less
Authors:
 [1] ;  [2] ; ; ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10]
  1. Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan)
  2. Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)
  3. Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States)
  4. Research Institute for Science and Engineering, Waseda University, 3- 4-1, Okubo, Shinjuku, Tokyo 169-8555 (Japan)
  5. Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo, Sagamihara, Kanagawa 252-5258 (Japan)
  6. UJF-Grenoble 1/CNRS-INSU, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble F-38041 (France)
  7. Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS/IN2P3, F-91128 Palaiseau (France)
  8. Landessternwarte, Universität Heidelberg, Königstuhl, D-69117 Heidelberg (Germany)
  9. Department of Physical Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)
  10. NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
Publication Date:
OSTI Identifier:
22356748
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 787; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; APPROXIMATIONS; BL LACERTAE OBJECTS; CATALOGS; CLASSIFICATION; DETECTION; EMISSION; ENERGY SPECTRA; GAMMA RADIATION; HARD X RADIATION; HYPOTHESIS; INFRARED SURVEYS; MAGNETIC FIELDS; PHOTONS; STARS; SYNCHROTRON RADIATION; TELESCOPES; X-RAY GALAXIES; X-RAY SPECTRA