Properties of a fading AGN from SDSS-IV MaNGA.

We identify a fading AGN SDSS J220141.64+115124.3 from the internal Product Launch-11 (MPL-11) in Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. The central region with a projected radius of |$\sim$| 2.4 kpc is characterized as LINER-like line ratios while the outskirts extended to |$\sim$| 15 kpc show Seyfert-like line ratios. The |${\rm{[O {\small III}]}}$| |$\lambda$| 5007 luminosity of the Seyfert regions is a factor of 37 (2) higher than the LINER regions without (with) dust attenuation correction, suggesting that the AGN activity decreases at least |$\sim$| 8 |$\times$| 10 |$^3$| yr (⁠|$\sim$| 2.4 kpc/light-speed) ago. We model the emission line spectra in the central region with double Gaussian components (a narrow core and a broad wing) and analyse the properties of each component. The narrow core component mostly co-rotates with the stellar disc, whereas the broad wing component with a median of the velocity dispersion |$\sim$| 300 km s ^{|$^{-1}$|} is related to a wind outflow. The kinematic position angle (PA) of the ionized gas shows an |$\sim 20^{\circ }$| twist from the galaxy centre to 1.5 effective radius. The median of the PA difference between the gas and stellar components is as large as |$\sim 50^{\circ }$| within 0.4 effective radius. The tidal feature in DESI image and star–gas misalignment suggest this galaxy is a merger remnant. Combining all these observational results as well as public available X-ray and MIR luminosities, we confirm this is a fading AGN, the merger process kick-started the central engine to quasar phase which ionized gas composed of tidal debris, and now the activity of the central black hole decreases. The discontinuity in |${\rm{[O {\small III}]}}$| |$\lambda$| 5007 flux and EQW maps is due to multiple AGN outbursts triggered by merger remnant gas inflows. [ABSTRACT FROM AUTHOR]