# Ideas about the origin of the “black hole - galaxy mass” relation?

It has been extensively shown that the mass of black-holes located at the center of galaxies scales with several galaxy properties, most notably the stellar velocity dispersion of the stellar bulge, which is an indicator of stellar mass. The origin of this relation remains controversial, and a leading candidate is AGN feedback. However, new studies (e.g., Woo et al. 2019; https://arxiv.org/pdf/1905.00145.pdf) show that the relation still exists on low-masses ranges (dwarf galaxies) where we do not expect AGN-feedback to be much significant. Therefore the question still remains: how such a correlation can exist? How the central BH 'knows' about galaxy mass (or viceversa)?

• The Woo et al. paper suggests that a single dwarf galaxy happens to fall on or near the relation; that doesn't mean that dwarf galaxies in general still obey the relation. There's been some work suggesting that black holes with masses $< 10^{7} M_{\odot}$ tend to scatter broadly, so this single data point is very meaningful. – Peter Erwin May 2 '19 at 11:21