Accretion and Host-Galaxy Properties of 14 New "Changing-Look'' Active Galactic Nuclei Identified from the SDSS-V Survey

TL;DR

This study identifies 14 new changing-look AGNs from SDSS data, analyzes their properties, and suggests they are in a transitional evolutionary stage, with implications for understanding AGN variability and the disk-wind broad-line-region model.

Contribution

The paper reports the discovery of 14 new changing-look AGNs and provides detailed spectral analysis, reinforcing biases against high Eddington ratios and luminosities, and proposing an evolutionary stage for these objects.

Findings

CL-AGNs tend to have low Eddington ratios and luminosities.

Host galaxies of CL-AGNs are dominated by intermediate stellar populations.

SDSS J025951.22+003744.2 is a newly identified rapid turn-on CL narrow-line Seyfert 1 galaxy.

Abstract

The widely accepted active galactic nucleus (AGN) paradigm has been recently challenged by the discovery of the so-called ``changing-look'' (CL) phenomenon characterized by spectral-type transitions. By comparing the SDSS-V and SDSS DR16 spectroscopic datasets, here we report the identification of 14 new CL-AGNs (redshift $z<0.5$) exhibiting spectral-type changes on a timescale of $\sim 10$yr. Follow-up spectroscopy was conducted with the Lick Shane 3m and Keck 10m telescopes for three of the objects. Detailed analysis of these spectra enables us to arrive at the following two main results. (1) By compiling a sample of 65 CL-AGNs with good measurements, we reinforce the previous claim that CL-AGNs tend to be biased against both a high Eddington ratio ($\lesssim 0.1$) and a high bolometric luminosity ($\lesssim 10^{46}\,\mathrm{erg\,s^{-1}}$). This bias suggests that the disk-wind broad-line-region model is a plausible explanation of the CL phenomenon. (2) The host galaxies of CL-AGNs tend to be dominated by intermediate stellar populations, which motivates us to propose that CL-AGNs are probably particular AGNs at a special evolutionary stage, such as a transition stage from ``feast'' to ``famine'' fueling of the supermassive black hole. In addition, with our spectra, we identify SDSS J025951.22+003744.2 as a new repeat CL narrow-line Seyfert 1 galaxy with a rapid ``turn-on'' timescale of $\sim 1$yr.