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 ~ sigma^4. Together
with a black hole mass M_BH ~ sigma^4 set by AGN momentum feedback, this
produces a linear M_BH - M_b relation. At low redshift this gives M_BH/M_b ~
0.001, 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.
