Jet-BLR connection in the radio galaxy 3C 390.3

TL;DR

This study reveals correlations between optical and radio emissions in the galaxy 3C 390.3, suggesting a model where jet-related ionization causes double-peaked emission lines at a specific distance from the nucleus.

Contribution

It introduces a new model linking jet activity with broad emission line formation through ionization of surrounding material in 3C 390.3.

Findings

Long-term optical variations correlate with radio emission from the jet base.

Optical variations follow radio flares with about one-year delay.

A model of ionized conical regions explains double-peaked emission lines.

Abstract

Variations of the optical continuum emission in the radio galaxy 3C 390.3 are compared to the properties of radio emission from the compact, sub-parsec-scale jet in this object. We showed that very long-term variations of optical continuum emission (>10 years) is correlated with the radio emission from the base of the jet located above the disk, while the optical long-term variations (1-2 years) follows the radio flares from the stationary component in the jet with time delay of about 1 year. This stationary feature is most likely to be a standing shock formed in the continuous relativistic flow seen at a distance of ~0.4 parsecs from the base of the jet. To account for the correlations observed we propose a model of the nuclear region of 3C 390.3 in which the beamed continuum emission from the jet and counterjet ionizes material in a subrelativistic outflow surrounding the jet. This results in the formation of two conical regions with double-peaked broad emission lines (in addition to the conventional broad line region around the central nucleus) at a distance ~0.6 parsecs from the central engine.