Mid-infrared variability of changing-look AGN

TL;DR

This study detects significant mid-infrared luminosity variations in 10 changing-look AGNs, supporting the idea that their transitions are driven by accretion rate changes rather than obscuration.

Contribution

It provides observational evidence linking mid-infrared variability to accretion rate changes in changing-look AGNs, using WISE and NEOWISE-R data.

Findings

Mid-infrared variability correlates with optical variability with expected dust reprocessing lag.

Large amplitude mid-infrared variations are inconsistent with obscuration scenarios.

Results support accretion rate changes as the primary driver of AGN type transitions.

Abstract

It is known that some active galactic nuclei (AGNs) transited from type 1 to type 2 or vice versa. There are two explanations for the so-called changing look AGNs: one is the dramatic change of the obscuration along the line-of-sight, the other is the variation of accretion rate. In this paper, we report the detection of large amplitude variations in the mid-infrared luminosity during the transitions in 10 changing look AGNs using WISE and newly released NEOWISE-R data. The mid-infrared light curves of 10 objects echoes the variability in the optical band with a time lag expected for dust reprocessing. The large variability amplitude is inconsistent with the scenario of varying obscuration, rather supports the scheme of dramatic change in the accretion rate.