# A Curved 150 Parsec Long Jet in the Double-Peaked Emission-Line AGN KISSR 434

## TL;DR

This study presents VLBI observations of the Seyfert galaxy KISSR 434, revealing a 150 parsec curved jet likely caused by precession, with implications for understanding AGN emission line features and jet dynamics.

## Contribution

First high-resolution VLBI imaging of KISSR 434 showing a long, curved jet, suggesting precession possibly due to a binary black hole or warped disk, and analyzing ionization mechanisms in the emission lines.

## Key findings

- Detected a 150 parsec curved jet in KISSR 434
- Jet likely precessing due to binary black hole or warped disk
- AGN photoionization explains emission line ratios, not shocks

## Abstract

Double-peaked emission lines in the narrow- and/or broad-line spectra of AGN have been suggested to arise due to disky broad/narrow line regions, jet-medium interaction, or the presence of binary supermassive black holes. We present the results from 1.5 and 4.9 GHz phase-referenced Very Long Baseline Interferometry (VLBI) observations of the Seyfert type 2 galaxy KISSR 434, which exhibits double-peaked emission lines in its optical spectrum. We detect a steep-spectrum ($\alpha<-1$), curved and long (~150 parsec) jet in the VLBI images of KISSR 434. The jet curvature could be a result of precession rather than ram-pressure bending from a rotating ISM. Precession could in turn arise due to a warped accretion disk or the presence of a binary black hole with a separation of 0.015 parsec, not accessible to present day telescopes. An examination of the emission line ratios with the MAPPINGS III code reveals that AGN photoionization is likely to be responsible for the observed line ratios and not shock-ionization due to the jet. A light (with jet-to-ambient medium density ratio of $\eta\sim0.01$) and fast (with speed $v_j\gtrsim0.75c$) precessing jet in KISSR 434 may have stirred up the emission-line gas clouds to produce the observed splits in the narrow line peaks but is not powerful enough to shock-ionise the gas.