Parsec-scale Nuclear Radio Structures in Seyfert Galaxies

TL;DR

This paper reviews radio outflows in Seyfert and LINER galaxies, highlighting the connection between parsec-scale jets and kiloparsec structures, and suggests episodic AGN activity as a key factor.

Contribution

It provides a comprehensive review of radio outflows across different scales in Seyfert and LINER galaxies, emphasizing the link between small-scale jets and large-scale structures.

Findings

VLBI observations suggest a connection between parsec-scale jets and kiloparsec radio structures.

Misalignment angles indicate prevalent bent outflows in Seyfert and LINER galaxies.

Multiple misaligned structures support episodic AGN activity.

Abstract

Radio outflows of extents ranging from a few parsecs to a few kiloparsecs are present in Seyfert and LINER galaxies that make up the `radio-quiet' AGN class. AGN jets and/or starburst superwinds have been suggested to produce these outflows. We present a brief review of radio outflows in Seyfert and LINER galaxies on different spatial scales. Very long baseline interferometry (VLBI) observations of several individual Seyferts and LINERs suggest a link between AGN jets on parsec-scales and their kiloparsec-scale radio structures (KSRs). The whole range of misalignment angles present between the parsec-scale and the kpc-scale outflows in Seyfert galaxies and LINERs, supports the prevalence of bent outflows in them. Episodic AGN activity is suggested by the presence of multiple misaligned KSRs in several Seyfert galaxies in total and polarized intensity images; this latter result provides further support for an AGN jet origin of the KSRs present in Seyfert and LINER galaxies.