Some things change, some don’t. An exploration of Seyfert galaxy luminosity changes over a generation

Abstract

In the 1980's some of the first systematic photometric studies established that Seyfert galaxies are variable on typical timescales of months. In some instances the luminosity, and even some of the spectral characteristics have changed dramatically over the years. In contrast, other AGN also classified as broad-line Seyferts have proved to be much more photometrically stable. The paper presents re-observations of several AGN obtained at SAAO in 2016-2017. These are used with other recent data to highlight a potential correlation between the spectral characteristics and the variability pattern. The significance of this correlation is briefly explored.