August 2018

The merger fraction of AGN host galaxies

Since our recent paper on the role of galaxy mergers for driving AGN activity is now accepted, I decided to show you once more a plot from this paper (Steinborn at al. 2018). At z=2, the merger fraction increases with AGN luminosity, in overall good agreement with several recent observations. At lower redshifts (z=0.1) the merger fraction does not depend on AGN luminosity and is always below 20%. Nevertheless, it is always somewhat higher than for inactive galaxies (arrows on the left-hand side). However, we caution the reader since this does not imply that the mergers cause AGN activity. Instead, we find that the above relation between the merger fraction and AGN luminosity is by a large amount driven by the different intrinsic properties of galaxies with and without a recent merger (see Steinborn at al. 2018 for details).