THE STRUCTURE AND EMISSION MODEL OF THE RELATIVISTIC JET IN THE QUASAR 3C 279 INFERRED FROM RADIO TO HIGH-ENERGY gamma-RAY OBSERVATIONS IN 2008-2010
2012 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 754, no 2, 114- p.Article in journal (Refereed) Published
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 gamma-ray/optical flare accompanied by a change in optical polarization, we found that the optical emission appears to be delayed with respect to the gamma-ray emission by about 10 days. X-ray observations reveal a pair of isolated flares separated by similar to 90 days, with only weak gamma-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 gamma-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 gamma-ray flaring event by a shift of its location from similar to 1 pc to similar to 4 pc from the central black hole. On the other hand, if the gamma-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.
Place, publisher, year, edition, pages
2012. Vol. 754, no 2, 114- p.
galaxies: active, galaxies: jets, gamma rays: galaxies, quasars: individual (3C 279), radiation mechanisms: non-thermal, X-rays: galaxies
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:su:diva-80094DOI: 10.1088/0004-637X/754/2/114ISI: 000306666700035OAI: oai:DiVA.org:su-80094DiVA: diva2:555331