Central Stellar Mass Deficits in the Bulges of Local Lenticular
  Galaxies, and the Connection with Compact z ~ 1.5 Galaxies
  We have used the full radial extent of images from the Hubble Space
Telescope's Advanced Camera for Surveys and Wide Field Planetary Camera 2 to
extract surface brightness profiles from a sample of six, local lenticular
galaxy candidates. We have modelled these profiles using a core-Sersic bulge
plus an exponential disk model. Our lenticular disk galaxies with bulge
magnitudes M_V < ~ -21.30 mag have central stellar deficits, suggesting that
these bulges may have formed from `dry' merger events involving supermassive
black holes while their surrounding disk was subsequently built up, perhaps via
cold gas accretion scenarios. The central stellar mass deficits M_def are
roughly 0.5 to 2 M_BH (black hole mass), rather than ~ 10 to 20 M_BH as claimed
from some past studies, which is in accord with core-Sersic model mass deficit
measurements in elliptical galaxies. Furthermore, these bulges have Sersic
indices n ~ 3, half light radii R_e < 2 kpc and masses > 10^11 M_sun, and
therefore appear to be descendants of the compact galaxies reported at z ~ 1.5
to 2. Past studies which have searched for these local counterparts by using
single-component galaxy models to provide the z ~ 0 size comparisons have
over-looked these dense, compact and massive bulges in today's early-type disk
galaxies. This evolutionary scenario not only accounts for what are today
generally old bulges---which must be present in z ~ 1.5 images---residing in
what are generally young disks, but it eliminates the uncomfortable suggestion
of a factor of 3 to 5 growth in size for the compact, z ~ 1.5 galaxies that are
known to possess infant disks.
