3-D Radiative Transfer Calculations of Radiation Feedback from Massive
  Black Holes: Outflow of Mass from the Dusty "Torus"
  Observational and theoretical arguments suggest that the momentum carried in
mass outflows from AGN can reach several times L / c, corresponding to outflow
rates of hundreds of solar masses per year. Radiation pressure on lines alone
may not be sufficient to provide this momentum deposition, and the transfer of
reprocessed IR radiation in dusty nuclear gas has been postulated to provide
the extra enhancement. The efficacy of this mechanism, however, will be
sensitive to multi-dimensional effects such as the tendency for the reprocessed
radiation to preferentially escape along sight-lines of lower column density.
We use Monte Carlo radiative transfer calculations to determine the radiation
force on dusty gas residing within approximately 10 parsecs from an accreting
super-massive black hole. We calculate the net rate of momentum deposition in
the surrounding gas and estimate the mass-loss rate in the resulting outflow as
a function of solid angle for different black hole luminosities,
sightline-averaged column densities, clumping parameters, and opening angles of
the dusty gas. We find that these dust-driven winds carry momentum fluxes of
1-5 times L / c and correspond to mass-loss rates of 10-100 solar masses per
year for a 10^8 solar mass black hole radiating at or near its Eddington limit.
These results help to explain the origin of high velocity molecular and atomic
outflows in local ULIRGs, and can inform numerical simulations of galaxy
evolution including AGN feedback.
