Hubble Space Telescope Imaging of Post-Starburst Quasars
  We present images of 29 post-starburst quasars (PSQs) from a Hubble Space
Telescope (\emph{HST}) Advanced Camera for Surveys (ACS) Wide Field Channel
Snapshot program. These broad-lined active galactic nuclei (AGN) possess the
spectral signatures of massive ($M_{burst} \sim 10^{10} M_{\odot}$),
moderate-aged stellar populations (hundreds of Myrs). Thus, their composite
nature provides insight into the AGN-starburst connection. We measure
quasar-to-host galaxy light contributions via semi-automated two-dimensional
light profile fits of PSF-subtracted images. We examine the host morphologies,
as well as, model the separate bulge and disk components. The
\emph{HST}/ACS-F606W images reveal an equal number of spiral (13/29) and
early-type (13/29) hosts, with the remaining three hosts having indeterminate
classifications. AGNs hosted by early-type galaxies have on average greater
luminosity than those hosted by spiral galaxies. Disturbances, such as tidal
tails, shells, star-forming knots, and asymmetries are seen as signposts of
interaction/merger activity. Disturbances such as these were found in 17 of the
29 objects and are evenly distributed among early-type and spiral galaxies. Two
of these systems are clearly merging with their companions. Compared to other
AGN of similar luminosity and redshift these PSQs have a higher fraction of
early-type hosts and disturbances. Our most luminous objects with disturbed
early-type host galaxies appear to be consistent with merger products. Thus,
these luminous disturbed galaxies may represent a phase in an evolutionary
scenario for merger driven activity and of hierarchical galaxy evolution. Our
less luminous objects appear to be consistent with Seyfert galaxies not
requiring triggering by major mergers. Many of these Seyferts are barred spiral
galaxies.
