The Connection between the Radio Jet and the γ-ray Emission in the Radio Galaxy 3C 120 and the Blazar CTA 102

Abstract

We present multi-wavelength studies of the radio galaxy 3C 120 and the blazar CTA 102 during unprecedented γ-ray flares for both sources. In both studies the analysis of γ-ray data has been compared with a series of 43 GHz VLBA images from the VLBA-BU-BLAZAR program, providing the necessary spatial resolution to probe the parsec scale jet evolution during the high Galaxies 2016, 4, 34; doi:10.3390/galaxies4040034www.mdpi.com/journal/galaxies Galaxies 2016, 4, 34 2 of 9 energy events. To extend the radio dataset for 3C 120 we also used 15 GHz VLBA data from the MOJAVE sample. These two objects which represent very different classes of AGN, have similar properties during the γ-ray events. The γ-ray flares are associated with the passage of a new superluminal component through the mm VLBI core, but not all ejections of new components lead to γ-ray events. In both sources γ-ray events occurred only when the new components are moving in a direction closer to our line of sight. We locate the γ-ray dissipation zone a short distance from the radio core but outside of the broad line region, suggesting synchrotron self-Compton scattering as the probable mechanism for the γ-ray production.

Jetted Narrow-Line Seyfert 1 Galaxies & Co.: where do we stand?

“…• 3C 120 (z = 0.033) [209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230];…”

3C 120 Disk/Corona vs. Jet Variability in X-rays

“…As shown in [21,22], there is a significant correlation between the dips and flares on the radio, optical, and X-ray light curves, which can be considered as a sign of the effect of the "jet base" in the direct vicinity of the "central engine" in AGN. As estimated in [23], based on Fermi and VLBI observations of 3C 120, the sources of the synchrotron radio-emission and the inverse Compton (IC)/synchrotron-self-Compton (SSC) γ-ray emission are located approximately within ∼0.24 pc and ∼0.13 pc around the central massive black hole of 3C 120, respectively. The Fermi observations of 3C 120 and a sample of other similar objects have revealed their variability on a 6-month timescale at high γ energies [24].…”

Polarization of broad line emission in radio galaxies

“…It should be noted that the properties of radiation of 3C 120 in γ‐ray, X‐ray, and radio frequencies are evidently connected to jet and during the flares optical radiation also could be affected by jet (Arshakian et al ; Casadio et al ; Chatterjee et al ; Marscher et al ). However, we believe that most of the time optical radiation originates from BLR of accretion disk.…”