Signatures of Feedback in the Spectacular Extended Emission Region of NGC 5972

Large clouds of ionized gas far from AGN, known as Extended Emission Line Regions (EELRs), promise a novel tool for getting a handle on the kiloyear timescale behavior of AGN accretion. These clouds are often considered as quasar light echoes, because their emission states can encode the AGN luminosity history over the past 100,000 years. AGN with current luminosity below the required luminosity to ionise the EELR are known as “fading AGN”. NGC 5972 contains the most extended known EELR and is thought to be a faded AGN, with 2 dex lower luminosity than 50 kiloyears ago. NGC 5972 is a complex system, so obscuration may also play a role in the variability, along with winds and outflows on different scales.

We present a new analysis of 3 Chandra observations of NGC 5972, totalling 50ks, which take advantage of Chandra’s sub-arcsecond angular resolution to analyse spectra, luminosity and potential spatial distribution of hot gas within the galaxy. By comparison to Chandra PSF simulations we determine that the soft (< 2keV) emission is spatially extended and show correlation with the HST [OIII] features, including the galaxy-scale EELR and an arcsecond scale nuclear bubble. We also present kinematic analysis of the nuclear bubble based on new Hubble STIS spectra. We are investigating the role of the AGN, jets and possible winds in exciting these features and how AGN state changes can contribute to emission patterns.