Massive Neutral Gas Outflow in Reddened Quasar SDSS J072910.34+333634.3
  SDSS J072910.34+333634.3 is a reddened quasar at z=0.96. The archivel
Keck/ESI spectrum and our new P200/TripleSpec spectrum reveal an absorption
line system in He I*, Ca II H\&K and Na ID. The absorption line system has a
width of $\sim$600 km/s and a blueshift velocity of $\sim$800 km/s relative to
the core of narrow emission lines, indicating an outflow. Using the Ca II
doublet, we determined that the outflowing gas covers $\sim$70\% of the
continuum. On the other hand, the HST/ACS image which taken in rest-frame 4130
\AA\ show that the fraction of the quasar emission in ESI aperture was $<$40\%.
We thus conclude that the absorbing gas covers a significant fraction of
extended starlight emission, and the best-estimated fraction of $\sim$50\%
yields a lower limit of the crosssectional area of the outflowing gas to be
$>$8 kpc$^2$. The strong Na\&Ca absorption suggests that the absorbing gas is
thick and mostly neutral, which is also supported by dust extinction
$A_V\sim3$. Using the best-estimated hydrogen column density
$N_H\sim3\times10^{22}$ cm$^{-2}$, the total mass of the outflowing gas is
$>3\times10^9 M_\odot$. The outflow is likely to be driven by AGN because of
the $\sim$800 km/s blueshift velocity, suggesting SDSS J072910.34+333634.3 is
undergoing one of the most violent AGN feedback we have seen. In the future,
one can find more such massive neutral gas outflows in other reddened quasars
using similar method, and this can shed new light on the study of AGN feedback.
