The Kiloparsec Scale Influence of the AGN in NGC 1068 with SALT RSS Fabry-P\'erot Spectroscopy

TL;DR

This study uses Fabry-Pérot spectroscopy with SALT RSS to examine how the active nucleus of NGC 1068 influences ionized gas on kiloparsec scales, confirming AGN-driven ionization and proposing a light-echo model of past activity.

Contribution

It demonstrates the effectiveness of FP spectroscopy for studying nearby Seyfert galaxies and introduces a toy model explaining ionization features as a light-echo from past AGN activity.

Findings

Ionized gas features are driven by AGN photoionization.

FP spectroscopy effectively studies kiloparsec-scale ionization.

Ionization features may be a light-echo from activity 2000 years ago.

Abstract

We present Fabry-P\'erot (FP) imaging and longslit spectroscopy of the nearby Seyfert II galaxy NGC 1068 using the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT) to observe the impact of the central Active Galactic Nucleus (AGN) on the ionized gas in the galaxy on kiloparsec scales. With SALT RSS FP we are able to observe the H$\alpha$+[N II] emission line complex over a $\sim$2.6 arcmin$^2$ field of view. Combined with the longslit observation, we demonstrate the efficacy of FP spectroscopy for studying nearby Type II Seyfert galaxies and investigate the kiloparsec-scale ionized gas in NGC 1068. We confirm the results of previous work from the TYPHOON/Progressive Integral Step Method (PrISM) survey that the kiloparsec-scale ionized features in NGC 1068 are driven by AGN photoionization. We analyze the spatial variation of the AGN intensity to put forward an explanation for the shape and structure of the kiloparsec-scale ionization features. Using a toy model, we suggest the ionization features may be understood as a light-echo from a burst of enhanced AGN activity $\sim$2000 years in the past.