2000/07/25 by Martin G. Haehnelt, Guinevere Kauffmann · 1 citation
Physics and Astronomy · #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.2000.03989.x
published as Mon.Not.Roy.Astron.Soc. 318 (2000) L35 · 5 pages, LaTeX, 3 postscript figures included; submitted to MNRAS
arxiv created 2000/07/25 · arxiv updated 2009/12/01
Recent work has demonstrated that there is a tight correlation between the mass of a black hole and the velocity dispersion of the bulge of its host galaxy. We show that the model of Kauffmann & Haehnelt, in which bulges and supermassive black holes both form during major mergers, produces a correlation between Mbh and sigma with slope and scatter comparable to the observed relation. In the model, the Mbh - sigma relation is significantly tighter than the correlation between black hole mass and bulge luminosity or the correlation between bulge luminosity and velocity dispersion. There are two reasons for this: i) the gas masses of bulge progenitors depend on the velocity dispersion but not on the formation epoch of the bulge, whereas the stellar masses of the progenitors depend on both; ii) mergers between galaxies move black holes along the observed Mbh - sigma relation, even at late times when the galaxies are gas-poor and black holes grow mainly by merging of pre-existing black holes. We conclude that the small scatter in the observed Mbh - sigma relation is consistent with a picture in which bulges and black holes form over a wide range in redshift.