No Small Scale Radio Jets Here: Multi-Epoch Observations of Radio Continuum Structures in NGC 1068 with the VLBA

TL;DR

This study uses multi-epoch VLBA radio observations of NGC 1068 to analyze the motion and origin of radio knots, revealing sub-relativistic speeds and suggesting shock-induced synchrotron emission from AGN-host interactions.

Contribution

First multi-epoch VLBA observations of NGC 1068 revealing detailed motion of radio knots and their likely origin from shock interactions in the host galaxy.

Findings

Radio knots have sub-relativistic speeds (<0.1c).

Radio emission likely caused by synchrotron radiation from shocks.

Interaction between AGN winds and host environment produces observed features.

Abstract

We present recent Very Long Baseline Array (VLBA) 5 GHz radio observations of the nearby, luminous Seyfert 2 galaxy NGC 1068 for comparison to similar VLBA observations made on 1997 April 26. By cross-correlating the positions of emitting regions across both epochs, we find that spatially-resolved extra-nuclear radio knots in this system have sub-relativistic transverse speeds (v < 0.1c). We discuss sources of the observed knots and how the radio emission relates to additional phases of gas in the central ~150 pcs of this system. We suggest that the most likely explanation for the observed emission is synchrotron radiation formed by shocked host media via interactions between AGN winds and the host environment.