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Title: From radio to TeV: the surprising spectral energy distribution of AP Librae

Following the discovery of high-energy (HE; E > 10 MeV) and very-high-energy (VHE; E > 100 GeV) γ-ray emission from the low-frequency-peaked BL Lac (LBL) object AP Librae, its electromagnetic spectrum is studied over 60 octaves in energy. Contemporaneous data in radio, optical and UV together with the (non-simultaneous) γ-ray data are used to construct the most precise spectral energy distribution of this source. We found that the data was modelled with difficulties with single-zone homogeneous leptonic synchrotron self-Compton (SSC) radiative scenarios due to the unprecedented width of the HE component when compared to the lower-energy component. Furthermore, the two other LBL objects also detected at VHE appear to have similar modelling difficulties. Nevertheless, VHE γ-rays produced in the extended jet could account for the VHE flux observed by HESS.
 [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [2] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [11]
  1. Univ. of Savoy (France). Annecy-le-Vieux Particle Physics Lab.
  2. Ecole Polytechnique Federale Lausanne (Switzlerland). Leprince-Ringuet Lab.
  3. Harvard-Smithsonian Center for Astrophysics, Amado, AZ (United States). Fred Lawrence Whipple Observatory
  4. Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology. Dept. of Physics; SLAC National Accelerator Lab., Menlo Park, CA (United States)
  5. Stanford Univ., CA (United States); Univ. of Wurzburg (Germany)
  6. US Naval Research Lab., Washington, DC (United States)
  7. Univ. of Wurzburg (Germany)
  8. Astro Space Center of Lebedev Physical Inst., Moscow (Russia); Max Planck Inst. for Radio Astronomy, Bonn (Germany)
  9. Purdue Univ., West Lafayette, IN (United States). Dept. of Physics
  10. Max Planck Inst. for Radio Astronomy, Bonn (Germany); Crimean Astrophysical Observatory (Russia); Pulkova Observatory, St. Petersburg (Russia)
  11. Max Planck Inst. for Radio Astronomy, Bonn (Germany); Aalto Univ., Kylmala (Finland). Metsahovi Radio Observatory
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 454; Journal Issue: 3; Journal ID: ISSN 0035-8711
Royal Astronomical Society
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
Contributing Orgs:
Fermi LAT Collaboration
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; galaxies: active; BL lacertae objects: individual: AP librae; galaxies: jets
OSTI Identifier: