# Observational evidence for the link between the variable optical continuum and the subparsec-scale jet of the radio galaxy 3C 390.3 - Astrophysics > Cosmology and Nongalactic Astrophysics

Abstract: The mechanism and the region of generation of variable continuum emission arepoorly understood for radio-loud AGN because of a complexity of the nuclearregion. High-resolution radio VLBI very long baseline interferometryobservations allow zooming into a subparsec-scale region of the jet in theradio-loud galaxy 3C 390.3. We combined the radio VLBI and the optical datacovering the time period of 14 years to look for a link between optical flaresand parsec-scale jet. We identify two stationary and nine moving radio featuresin the innermost subparsec-scale region of the jet. All nine ejections areassociated with optical flares. We found a significant correlation at aconfidence level of $>99.99%$ between the ejected jet components and opticalcontinuum flares. The epochs at which the moving knots pass through thelocation of a stationary radio feature and the optical light curve reaches themaximum are correlated. The radio events follow the maxima of optical flareswith the mean time delay of $0.10\pm0.04$ years. This correlation can beunderstood if the variable optical continuum emission is generated in theinnermost part of the jet. A possible mechanism of the energy release is theejection of knots of high-energy electrons that are accelerated in the jet flowand generate flares of synchrotron continuum emission in the wide range offrequencies from radio to X-ray bands. In this scenario, the beamed opticalcontinuum emission from the jet and counterjet ionizes a gas in asubrelativistic outflow surrounding the jet, which results in a formation oftwo outflowing conical regions with broad emission lines in addition to theconventional broad line region around the central nucleus.

Author: T.G. Arshakian, J. Leon-Tavares, A.P. Lobanov, V.H. Chavushyan, A.I. Shapovalova, A.N. Burenkov, J.A. Zensus

Source: https://arxiv.org/