Speaker
Description
Active galactic nucleus (AGN) growth in disk-dominated, merger-free galaxies is poorly understood, largely due to the difficulty in disentangling the AGN emission from that of the host galaxy. By carefully separating this emission, we examine the differences between AGN in galaxies hosting a (possibly) merger-grown, classical bulge, and AGN in secularly grown, truly bulgeless disk galaxies. We use Galfit to obtain robust, accurate morphologies of 100 disk-dominated galaxies imaged with the Hubble Space Telescope. Adopting an inclusive definition of classical bulges, we detect a classical bulge component in 53.3 ± 0.5% of the galaxies. These bulges were not visible in Sloan Digital Sky Survey photometry; however, these galaxies are still unambiguously disk-dominated, with an average bulge-to-total luminosity ratio of 0.1 ± 0.1. We find some correlation between bulge mass and black hole mass for disk-dominated galaxies, though this correlation is significantly weaker in comparison to the relation for bulge-dominated or elliptical galaxies. Furthermore, a significant fraction (~ 90%) of our black holes are overly massive when compared to the relationship for elliptical galaxies. We find a weak correlation between total stellar mass and black hole mass for the disk-dominated galaxies, hinting that the stochasticity of black hole-galaxy co-evolution may be higher in disk-dominated than bulge-dominated systems.
