Detection of quasars in the time domain

Abstract

Abstract. The time domain is the emerging forefront of astronomical research with new facilities and instruments providing unprecedented amounts of data on the temporal behavior of astrophysical populations. Dealing with the size and complexity of this requires new techniques and methodologies. Quasars are an ideal work set for developing and applying these: they vary in a detectable but not easily quantifiable manner whose physical origins are poorly understood. In this paper, we will review how quasars are identified by their variability and how these techniques can be improved, what physical insights into their variability can be gained from studying extreme examples of variability, and what approaches can be taken to increase the number of quasars known. These will demonstrate how astroinformatics is essential to discovering and understanding this important population.

SkyMapper colours of Seyfert galaxies and Changing-Look AGN

“…Monitoring the sky for variable objects provided a separate approach to identify AGN, at least those whose usually variable and UV-optically luminous accretion disk was not obscured by dust (e.g. Hawkins & Veron 1993;Graham et al 2017). Variability was recognised as ubiquitous long ago, but it was long assumed that it could not be strong enough to change profoundly the spectral type of an AGN (Lawrence 2018, and references therein).…”