July 2018

How ‘universal’ is the relation between bulge mass and BH mass?

This plot, which is taken from the introduction of my PhD thesis, summarises observations, which find a relationship between the bulge mass of galaxies and the mass of their central SMBHs. Especially interesting is that this relation (and also the M-sigma relation) seems to hold not for all galaxy types. Traditionally, it is thought to be valid only for early-type galaxies. Scott et al. (2013) find different relations for galaxies with and without a core. Furthermore, disturbed systems like mergers (green stars, Kormendy & Ho 2013), are below this relation.
My personal opinion is that only systems which are in equilibrium follow this relation, whereas others lie below and do probably not follow any relation at all, because they can be in very different non-equilibrium stages.