Detailed accretion history of the supermassive black hole in NGC 5972 over the past $\gtrsim$10$^4$ years through the extended emission line region
We present integral field spectroscopic observations of NGC 5972 obtained with the Multi Unit Spectroscopic Explorer (MUSE) at VLT. NGC 5972 is a nearby galaxy containing both an active galactic nucleus (AGN), and an extended emission line region (EELR) reaching out to $\sim 17$ kpc from the nucleus...
Saved in:
Main Authors | , , , , , , , , , , |
---|---|
Format | Journal Article |
Language | English |
Published |
09.08.2022
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | We present integral field spectroscopic observations of NGC 5972 obtained
with the Multi Unit Spectroscopic Explorer (MUSE) at VLT. NGC 5972 is a nearby
galaxy containing both an active galactic nucleus (AGN), and an extended
emission line region (EELR) reaching out to $\sim 17$ kpc from the nucleus. We
analyze the physical conditions of the EELR using spatially-resolved spectra,
focusing on the radial dependence of ionization state together with the light
travel time distance to probe the variability of the AGN on $\gtrsim 10^{4}$ yr
timescales. The kinematic analysis suggests multiple components: (a) a faint
component following the rotation of the large scale disk; (b) a component
associated with the EELR suggestive of extraplanar gas connected to tidal
tails; (c) a kinematically decoupled nuclear disk. Both the kinematics and the
observed tidal tails suggest a major past interaction event. Emission line
diagnostics along the EELR arms typically evidence Seyfert-like emission,
implying that the EELR was primarily ionized by the AGN. We generate a set of
photoionization models and fit these to different regions along the EELR. This
allows us to estimate the bolometric luminosity required at different radii to
excite the gas to the observed state. Our results suggests that NGC 5972 is a
fading quasar, showing a steady gradual decrease in intrinsic AGN luminosity,
and hence the accretion rate onto the SMBH, by a factor $\sim 100$ over the
past $5 \times 10^{4}$ yr. |
---|---|
DOI: | 10.48550/arxiv.2208.04911 |