Strong Candidate for AGN Feedback: VLT/X-shooter Observations of BALQSO
  SDSS J0831+0354
  We measure the location and energetics of a SIV BALQSO outflow. This ouflow
has a velocity of 10,800 km s$^{-1}$ and a kinetic luminosity of $10^{45.7}$
erg s$^{-1}$, which is 5.2% of the Eddington luminosity of the quasar. From
collisional excitation models of the observed SIV$/$SIV* absorption troughs, we
measure a hydrogen number density of $n_\mathrm{\scriptscriptstyle H}=10^{4.3}$
cm$^{-3}$, which allows us to determine that the outflow is located 110 pc from
the quasar. Since SIV is formed in the same ionization phase as CIV, our
results can be generalized to the ubiquitous CIV BALs. Our accumulated distance
measurements suggest that observed BAL outflows are located much farther away
from the central source than is generally assumed (0.01-0.1 pc).
