Quiescent Compact Galaxies at Intermediate Redshift in the COSMOS Field.
  The Number Density
  We investigate the evolution of compact galaxy number density over the
redshift range $0.2<z<0.8$. Our sample consists of galaxies with secure
spectroscopic redshifts observed in the COSMOS field. With the large
uncertainties, the compact galaxy number density trend with redshift is
consistent with a constant value over the interval $0.2<z<0.8$. Our number
density estimates are similar to the estimates at $z>1$ for equivalently
selected compact samples. Small variations in the abundance of the COSMOS
compact sources as a function of redshift correspond to known structures in the
field. The constancy of the compact galaxy number density is robust and
insensitive to the compactness threshold or the stellar mass range (for
$M_\ast>10^{10}\, M_\odot$). To maintain constant number density any size
growth of high-redshift compact systems with decreasing redshift must be
balanced by formation of quiescent compact systems at $z<1$.
