Two Epochs of VLBI Observations of 8 KISSR Seyfert & LINER Galaxies: Suggestions of Fast and Filamentary Outflows

TL;DR

This study presents multi-epoch VLBI observations of 8 Seyfert and LINER galaxies, revealing persistent and evolving parsec-scale jets, superluminal motions, and structures suggesting AGN-driven outflows and interactions with their environment.

Contribution

First multi-epoch VLBI study of KISSR Seyfert and LINER galaxies showing jet persistence, superluminal motions, and detailed jet-environment interactions in radio-quiet AGN.

Findings

Detection of parsec-scale radio emission in 7 of 8 sources.

Evidence of superluminal jet motion in two sources.

Jets lose collimation over 200 parsec to 1 kpc scales.

Abstract

We present here the results from a second epoch of phase-referenced VLBA observations of 8 Seyfert and LINER galaxies from the KISSR sample. These sources were chosen based on the presence of double peaks or asymmetries in their emission lines as observed in SDSS spectra. Parsec-scale radio emission is detected in 7 of the 8 sources in the second epoch. Jet-like features appear to persist over a $\sim4-9$ year timeline in these `radio-quiet' AGN. A few sources like KISSR1494, however, show significantly different structures after a 9 year interval. KISSR102, which was previously suggested to be a binary black hole candidate based on the presence of two compact cores, shows the tentative signatures of superluminal jet motion ($1.05\pm0.45$c). Tentative superluminal motion in a jet knot has been reported in another source, KISSR872 ($1.65\pm0.57$c). We present 1.5 GHz images from the VLA A-array of 4 sources. These images reveal core-lobe or core-halo structures. The alignment of the VLBI jet direction with the kpc-scale spectral index gradient, as well as the mismatch between the star formation rate derived from the radio and H$\alpha$ line emission, support the suggestion that the kpc-scale emission is AGN-jet-related. The jets in KISSR sources appear to lose collimation over spatial scales between 200 parsec and 1 kpc. Overall, the characteristics of the KISSR jets are reminiscent of similar properties observed in VLBI monitoring studies of `radio-loud' AGN jets even as subtle differences related to the compactness and brightness of jet features remain.