Clues to the Structure of AGN through massive variability surveys

TL;DR

This paper reviews how large-scale variability surveys like SDSS, PanSTARRS, and LSST are advancing our understanding of AGN structure by analyzing optical and UV variability, including rare events like Tidal Disruption Events and changing-look AGN.

Contribution

It synthesizes recent findings from variability surveys, highlighting new insights into AGN physics and the significance of rare large-scale outbursts.

Findings

Variability studies reveal details of accretion discs and broad-line regions.

Large-scale surveys have identified rare events like Tidal Disruption Events.

Recent results include observations of changing-look AGN and microlensing phenomena.

Abstract

Variability studies hold information on otherwise unresolvable regions in Active Galactic Nuclei (AGN). Population studies of large samples likewise have been very productive for our understanding of AGN. These two themes are coming together in the idea of systematic variability studies of large samples - with SDSS, PanSTARRS, and soon, LSST. I summarise what we have learned about the optical and UV variability of AGN, and what it tells us about accretion discs and the BLR. The most exciting recent results have focused on rare large-scale outbursts and collapses - Tidal Disruption Events, changing-look AGN, and large amplitude microlensing. All of these promise to give us new insight into AGN physics.