Properties of a fading AGN from SDSS-IV MaNGA

Abstract

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 2.4 kpc is characterized as LINER-like line ratios while the outskirts extended to 15 kpc show Seyfert-like line ratios. The 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 8 10 yr (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 300 km sis related to a wind outflow. The kinematic position angle (PA) of the ionized gas shows an 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 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 5007 flux and EQW maps is due to multiple AGN outbursts triggered by merger remnant gas inflows.