Two New "Turn-off" Changing-look Active Galactic nuclei and Implication on "Partially Obscured" AGNs

TL;DR

This paper reports the discovery of two new changing-look AGNs with a 'turn-off' transition, analyzes their properties, and discusses implications for the nature of partially obscured AGNs and their variability mechanisms.

Contribution

The study identifies two new 'turn-off' changing-look AGNs and explores their relation to intermediate-type AGNs, highlighting different origins for their variability.

Findings

Two new 'turn-off' CL-AGNs identified.

Overlap between dim CL-AGNs and intermediate-type AGNs.

CL-AGNs tend to have low Eddington ratios.

Abstract

We here report a spectroscopic identification of two new changing-look AGNs (CL-AGNs): SDSS\,J104705.16+544405.8 and SDSS\,J120447.91+170256.8 both with a "turn-off" type transition from type 1 to type 1.8/1.9. The identification is arrived by a follow-up spectroscopic observation of the five changing-look AGN (CL-AGN) candidates that are extracted from the sample recently released in Macleod et al. The candidates are extract by the authors from the Sloan Digit Sky Survey Data Release 7 spectroscopically confirmed quasars with large amplitude variability. By compiling a sample of 26 previously identified CL-AGNs, we confirm the claim in Macleod et al. that CL-AGNs tend to be biased against low Eddington ratio, and identify an overlap between the CL-AGNs at their dim state and the so-called intermediate-type AGNs. The overlap implies that there two populations of the intermediate-type AGNs with different origins. One is due to the torus orientation effect, and the another the intrinsic change of the accretion rate of the central supermassive blackholes.