Quasar outflow energetics from broad absorption line variability
  Quasar outflows have long been recognized as potential contributors to the
co-evolution between supermassive black holes (SMBHs) and their host galaxies.
The role of outflows in AGN feedback processes can be better understood by
placing observational constraints on wind locations and kinetic energies. We
utilize broad absorption line (BAL) variability to investigate the properties
of a sample of 71 BAL quasars with P$\thinspace$V broad absorption. The
presence of P$\thinspace$V BALs indicates that other BALs like C$\thinspace$IV
are saturated, such that variability in those lines favours clouds crossing the
line of sight. We use these constraints with measurements of BAL variability to
estimate outflow locations and energetics. Our data set consists of
multiple-epoch spectra from the Sloan Digital Sky Survey and MDM Observatory.
We detect significant (4$\sigma$) BAL variations from 10 quasars in our sample
over rest frame time-scales between < 0.2-3.8 yr. Our derived distances for the
10 variable outflows are nominally < 1-10 pc from the SMBH using the
transverse-motion scenario, and < 100-1000 pc from the central source using
ionization-change considerations. These distances, in combination with the
estimated high outflow column densities (i.e. $N_{\textrm{H}}$ > 10$^{22}$
cm$^{-2}$), yield outflow kinetic luminosities between ~ 0.001-1 times the
bolometric luminosity of the quasar, indicating that many absorber energies
within our sample are viable for AGN feedback.
