Probing the gamma-ray variability in 3C279 using broadband observations

Abstract

We present the results of a broadband radio-to-GeV observing campaign organized to get a better understanding of the radiation processes responsible for the $\gamma$-ray flares observed in 3C 279. The total intensity and polarization observations of the source were carried out between December 28, 2013 and January 03, 2014 using the Fermi-LAT, Swift-XRT, Swift-UVOT, and KVN telescopes. A prominent flare observed in the optical/near-UV passbands was found to be correlated with a concurrent $\gamma$-ray flare at a confidence level $>$95$\%$, which suggests a co-spatial origin of the two. Moreover, the flaring activity in the two regimes was accompanied by no significant spectral variations. A peak in the X-ray light curve coincides with the peaks of the fractional polarization curves at 43 and 86 GHz radio bands. No prominent variation was noticed for the total intensity and the electric vector position angle (EVPA) observations at radio bands during this period. We noticed a possible hint of steepening of the radio spectrum with an increase in percentage polarization, which suggests that the radio polarization variations could be simply due to a spectral change. In a simple scenario, the correlated optical/$\gamma$-ray flares could be caused by 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. The observed fractional variability for the $\gamma$-ray flare $\sim$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.

10 pages, 8 figures, accepted for publication in MNRAS

References in corpus (13)

• Very-High-Energy Gamma Rays from a Distant Quasar: How Transparent Is the Universe?
• A change in the optical polarization associated with a gamma-ray flare in the blazar 3C 279
• Modeling the Emission Processes in Blazars
• MOJAVE: Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments. VIII. Faraday rotation in parsec-scale AGN jets
• Rapid Variability of Blazar 3C 279 during Flaring States in 2013-2014 with Joint Fermi-LAT, NuSTAR, Swift, and Ground-Based Multi-wavelength Observations
• Correlated Multi-Waveband Variability in the Blazar 3C~279 from 1996 to 2007
• Multiwaveband Polarimetric Observations of 15 Active Galactic Nuclei at High Frequencies: Correlated Polarization Behavior
• Results of WEBT, VLBA and RXTE monitoring of 3C 279 during 2006-2007
• The multiwavelength variability of 3C 273
• The WEBT Campaign on the Blazar 3C279 in 2006
• Temporal Correlations Between Optical and Gamma-ray Activity in Blazars
• Jet outflow and gamma-ray emission correlations in S5 0716+714
• Connection between inner jet kinematics and broadband flux variability in the BL Lac object S5 0716+714

Cited by in corpus (2)

• Broadband variability and correlation study of 3C 279 during flare of 2017-2018
• Multiwavelength analysis of brightness variations of 3C~279: Probing the relativistic jet structure and its evolution