2013/04/30 by C. D. Dermer, Charles D. Dermer, Matteo Cerruti +7 · 1 citation
Physics and Astronomy · #Astrophysics #Astrophysics and Cosmic Phenomena #Black hole (networking) #Blazar #Dark Matter and Cosmic Phenomena #Electron #Equipartition theorem #Fermi Gamma-ray Space Telescope #Flare #Galaxy #Gamma ray #Geometry #Jet (fluid) #Lorentz factor #Lorentz transformation #Luminosity #Magnetic field #Nuclear physics #Physics #Radio Astronomy Observations and Technology #Torus #astro-ph.HE
paper · pdf · doi:10.1088/0004-637x/782/2/82
17 pages, 8 figures. Accepted from publication in ApJ
arxiv created 2014/01/09 · openalex publication_date 2014/01/30 · arxiv updated 2015/06/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Blazar spectral models generally have numerous unconstrained parameters, leading to ambiguous values for physical properties like Doppler factor δ 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 D , B ', and the peak electron Lorentz factor . 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 D ∼ 20–30, B ' ∼ few G, and total (IR + BLR) external radiation field energy densities u ∼ 10 −2 –10 −3 erg cm −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 2 ct var ∼ 0.1(Γ/30) 2 ( t var /10 4 s) pc from the black hole powering 3C 279's jets, where t 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.