The Structure and Emission Model of the Relativistic Jet in the Quasar 3C 279 Inferred from Radio to High-energy γ-Ray Observations in 2008-2010
Abstract
We present time-resolved broadband observations of the quasar 3C 279 obtained from multi-wavelength campaigns conducted during the first two years of the Fermi Gamma-ray Space Telescope mission. While investigating the previously reported γ-ray/optical flare accompanied by a change in optical polarization, we found that the optical emission appears to be delayed with respect to the γ-ray emission by about 10 days. X-ray observations reveal a pair of "isolated" flares separated by ~90 days, with only weak γ-ray/optical counterparts. The spectral structure measured by Spitzer reveals a synchrotron component peaking in the mid-infrared band with a sharp break at the far-infrared band during the γ-ray flare, while the peak appears in the millimeter (mm)/submillimeter (sub-mm) band in the low state. Selected spectral energy distributions are fitted with leptonic models including Comptonization of external radiation produced in a dusty torus or the broad-line region. Adopting the interpretation of the polarization swing involving propagation of the emitting region along a curved trajectory, we can explain the evolution of the broadband spectra during the γ-ray flaring event by a shift of its location from ~1 pc to ~4 pc from the central black hole. On the other hand, if the γ-ray flare is generated instead at sub-pc distance from the central black hole, the far-infrared break can be explained by synchrotron self-absorption. We also model the low spectral state, dominated by the mm/sub-mm peaking synchrotron component, and suggest that the corresponding inverse-Compton component explains the steady X-ray emission.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2012
- DOI:
- 10.1088/0004-637X/754/2/114
- arXiv:
- arXiv:1206.0745
- Bibcode:
- 2012ApJ...754..114H
- Keywords:
-
- galaxies: active;
- galaxies: jets;
- gamma rays: galaxies;
- quasars: individual: 3C 279;
- radiation mechanisms: non-thermal;
- X-rays: galaxies;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 23 pages, 18 figures 5 tables, Accepted for publication in The Astrophysical Journal