Self-regulated star formation and the black hole-galaxy bulge relation

We show that star formation in galaxy bulges is self-regulating through momentum feedback, limiting the stellar bulge mass to M-b proportional to sigma(4). Together with a black hole mass M-BH proportional to sigma(4) set by active galactic nucleus (AGN) momentum feedback, this produces a linear M-BH-M-b relation. At low redshift this gives M-BH/M-b similar to 10(-3), close to the observed ratio. We show that AGN feedback can remove any remaining gas from the bulge and terminate star formation once the central black hole reaches the M-BH-sigma value, contrary to earlier claims. We find a mild upward deviation from the sigma(4) law at higher redshift and at higher sigma.