Feedback from Accreting Black Holes: The Importance of Momentum Driving

Black holes, resident in the centers of galaxies, will be fed by
accretion of ambient gas whenever gas reaches those central
regions. This can be due to mergers, but even without mergers the
evolution of the stellar populations of normal galaxies provides very
large amounts of gas, as stars pass through the planetary nebula
stage, the total mass release being greater than 10$^{11}$ Msolar for
massive ellipticals. Much of that gas will cool and fall to the
centers of the systems, where it will induce starbursts and accretion
events onto the central black holes. Accretion then induces outbursts
of UV from the BH discs, Xrays from coronal gas and polar, radiation
driven winds, with the efficiencies in these three categories roughly
10$^{-1}$, 10$^{-2}$ \& 10$^{-3}$.  The mass, momentum and energy in
these outbursts can have dramatic consequences for the growth of the
BH and for the ambient galaxy. Most AGN feedback treatments do not
include the mass and momentum components. We follow these events with
1D, 2D and 3D hydrodynamic codes. BH growth is similar to what has
been found by others, but the momentum driving produces much more
energetic winds than does thermal feedback. Observable consequences
include the narrow line AGN absorption lines, shock accelerated
synchrotron emitting particles and wind driven bubbles in the IGM. In
addition, we find that the feedback strongly inhibits inflow, causing
episodic accretion and a low ``duty cycle''. The simulations help us
to understand many phenomena including the black hole stellar mass
relation, the paucity of gas in ellipticals, the incidence of the
¡°E+A¡± phenomena and the observed fact that most of the black holes
found in galactic centers are found in the ``off'' state.