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Title: Equipartition gamma-ray blazars and the location of the gamma-ray emission site in 3C 279

Blazar spectral models generally have numerous unconstrained parameters, leading to ambiguous values for physical properties like Doppler factor δ{sub D} or fluid magnetic field B'. To help remedy this problem, a few modifications of the standard leptonic blazar jet scenario are considered. First, a log-parabola function for the electron distribution is used. Second, analytic expressions relating energy loss and kinematics to blazar luminosity and variability, written in terms of equipartition parameters, imply δ{sub D}, B', and the peak electron Lorentz factor γ{sub pk}{sup ′}. The external radiation field in a blazar is approximated by Lyα radiation from the broad-line region (BLR) and ≈0.1 eV infrared radiation from a dusty torus. When used to model 3C 279 spectral energy distributions from 2008 and 2009 reported by Hayashida et al., we derive δ{sub D} ∼ 20-30, B' ∼ few G, and total (IR + BLR) external radiation field energy densities u ∼ 10{sup –2}-10{sup –3} erg cm{sup –3}, implying an origin of the γ-ray emission site in 3C 279 at the outer edges of the BLR. This is consistent with the γ-ray emission site being located at a distance R ≲ Γ{sup 2} ct {sub var} ∼ 0.1(Γ/30){sup 2}(t {sub var}/10{sup 4}more » s) pc from the black hole powering 3C 279's jets, where t {sub var} is the variability timescale of the radiation in the source frame, and at farther distances for narrow-jet and magnetic-reconnection models. Excess ≳ 5 GeV γ-ray emission observed with Fermi LAT from 3C 279 challenges the model, opening the possibility of a second leptonic component or a hadronic origin of the emission. For low hadronic content, absolute jet powers of ≈10% of the Eddington luminosity are calculated.« less
Authors:
 [1] ;  [2] ;  [3] ; ;  [4]
  1. Code 7653, Space Science Division, U.S. Naval Research Laboratory, Washington, DC 20375 (United States)
  2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  3. Centre d'Études Nucléaires Bordeaux Gradignan, Université de Bordeaux, CNRS/IN2P3, UMR 5797, F-33175 Gradignan (France)
  4. Laboratoire Univers et THeories (LUTH), Observatoire de Paris-Meudon, 5 Place Jules Janssen, F-92195 Meudon Cedex (France)
Publication Date:
OSTI Identifier:
22351435
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 782; 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; APPROXIMATIONS; BLACK HOLES; DISTANCE; DISTRIBUTION; ELECTRONS; EMISSION; ENERGY DENSITY; ENERGY LOSSES; ENERGY SPECTRA; GALAXIES; GAMMA RADIATION; GEV RANGE; INFRARED RADIATION; LUMINOSITY; MAGNETIC FIELDS; MAGNETIC RECONNECTION; MODIFICATIONS; ORIGIN