Discovering AGN-driven winds through their infrared emission: II. Mass
  outflow rate and energetics
  The global influence of AGN-driven outflows remains uncertain, due to a lack
of large samples with accurately-determined outflow properties. In the second
paper of this series, we determine the mass and energetics of ionized outflows
is 234 type II AGN, the largest such sample to date, by combining the infrared
emission of the dust in the wind (paper I) with the emission line properties.
We provide new general expressions for the properties of the outflowing gas,
which depend on the ionization state of the gas. We also present a novel method
to estimate the electron density in the outflow, based on optical line ratios
and on the known location of the wind. The inferred electron densities,
$n_{\mathrm{e}} \sim 10^{4.5}\,\mathrm{(cm^{-3})}$, are two orders of magnitude
larger than typically found in most other cases of ionized outflows. We argue
that the discrepancy is due to the fact that the commonly-used [SII]-based
method underestimates the true density by a large factor. As a result, the
inferred mass outflow rates and kinetic coupling efficiencies are
$\dot{M}_{\mathrm{out}} \sim 10^{-2}\, \mathrm{(M_{\odot}/yr)}$ and $\epsilon =
\dot{E}_{\mathrm{kin}}/L_{\mathrm{bol}} \sim 10^{-5}$ respectively, 1--2 orders
of magnitude lower than previous estimates. Our analysis suggests the existence
of a significant amount of neutral atomic gas at the back of the outflowing
ionized gas clouds, with mass that is a factor of a few larger than the
observed ionized gas mass. This has significant implications for the estimated
mass and energetics of such flows.
