On the Dearth of Compact, Massive, Red Sequence Galaxies in the Local
  Universe
  Using data from the Sloan Digital Sky Survey (SDSS; data release 7), we have
conducted a search for local analogs to the extremely compact, massive,
quiescent galaxies that have been identified at z > 2. We show that
incompleteness is a concern for such compact galaxies, particularly for low
redshifts (z < ~0.05) as a result of the SDSS spectroscopic target selection
algorithm. We have identified 63 massive red sequence galaxies at 0.066 < z <
0.12 that are smaller than the median size-mass relation by a factor of 2 or
more. Consistent with expectations from the virial theorem, the median offset
from the mass-velocity dispersion relation for these galaxies is 0.12 dex. We
do not find any galaxies with sizes and masses comparable to those observed at
z ~ 2, implying a decrease in the comoving number density (at fixed size and
mass) by a factor of > 5000. This result cannot be explained by incompleteness:
at 0.066 < z <0.12, the SDSS spectroscopic sample should typically be ~75%
complete for galaxies with the sizes and masses seen at high redshift, although
for the very smallest galaxies it may be as low as ~20%. To confirm that the
absence of such compact massive galaxies in SDSS is not a spectroscopic
selection effect, we have also looked for such galaxies in the SDSS photometric
catalog, using photometric redshifts. While we do find signs of a bias against
massive, compact galaxies, this analysis suggests that the SDSS spectroscopic
sample is missing at most a few objects in the regime we consider. Accepting
the high redshift results, it is clear that massive galaxies must undergo
significant structural evolution over z<2 in order to match the population seen
in the local universe. Our results suggest that a highly stochastic mechanism
like major mergers cannot be the primary driver of this strong size evolution.
