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Title: Probing the gamma-ray variability in 3C 279 using broad-band observations

In this study, we present the results of a broad-band radio-to-GeV observing campaign organized to get a better understanding of the radiation processes responsible for the γ-ray flares observed in 3C 279. The total intensity and polarization observations of the source were carried out between 2013 December 28 and 2014 January 03 using the Fermi-Large Area Telescope, Swift-XRT, Swift-UVOT, and Korean VLBI Network telescopes. A prominent flare observed in the optical/near-UV passbands was found to be correlated with a concurrent γ-ray flare at a confidence level >95 percent, which suggests a co-spatial origin of the two. Moreover, the flaring activity in the two regimes was accompanied by no significant spectral variations. A peak in the X-ray light curve coincides with the peaks of the fractional polarization curves at 43 and 86 GHz radio bands. No prominent variation was noticed for the total intensity and the electric vector position angle observations at radio bands during this period. We noticed a possible hint of steepening of the radio spectrum with an increase in percentage polarization, which suggests that the radio polarization variations could be simply due to a spectral change. In a simple scenario, the correlated optical/γ-ray flares could be caused bymore » the same population of emitting particles. The coincidence of the increase in radio polarization with the X-ray flux supports the picture that X-rays are produced via inverse-Compton scattering of radio photons. Finally, the observed fractional variability for the γ-ray flare ~0.23 does not exceed that in the optical regime, which is inconsistent with what we usually observe for 3C 279; it could be due to different dependencies of the magnetic field and the external radiation field energy density profiles along the jet.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [3] ;  [5] ;  [2]
  1. NASA Goddard Space Flight Center, Greenbelt, MD (United States); Max-Planck-Institut fur Radioastronomie (MPIfR) (Germany)
  2. Max-Planck-Institut fur Radioastronomie (MPIfR) (Germany)
  3. Korea Astronomy and Space Science Institute (Korea); University of Science and Technology (Korea)
  4. Astro Space Center of Lebedev Physical Institute, Moscow (Russia); IAASARS, National Observatory of Athens (Greece); Moscow State University (Russia). Sternberg Astronomical Institute
  5. Astro Space Center of Lebedev Physical Institute, Moscow (Russia)
Publication Date:
Grant/Contract Number:
AC02-76SF00515; 14-02-31789; NRF-2016R1C1B2006697
Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 464; Journal Issue: 1; 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, galaxies; jets, quasars; individual; 3C 279, gamma-rays; general, radio continuum; galaxies, X-rays
OSTI Identifier: