Sizes and surface brightness profiles of quiescent galaxies at z ~ 2
  We use deep Hubble Space Telescope Wide Field Camera 3 near-infrared imaging
obtained of the GOODS-South field as part of the CANDELS survey to investigate
a stellar mass-limited sample of quiescent galaxies at 1.5 < z < 2.5. We
measure surface brightness profiles for these galaxies using a method that
properly measures low surface brightness flux at large radii. We find that
quiescent galaxies at z ~ 2 very closely follow Sersic profiles, with
n_{median} = 3.7, and have no excess flux at large radii. Their effective radii
are a factor ~ 4 smaller than those of low-redshift quiescent galaxies of
similar mass. However, there is significant spread in sizes (sigma_{log r_e} =
0.24), with the largest z ~ 2 galaxies lying close to the z = 0 mass-size
relation. We compare the stellar mass surface density profiles with those of
massive elliptical galaxies in the Virgo cluster and confirm that most of the
mass-growth which occurs between z ~ 2 and z = 0 must be due to accretion of
material onto the outer regions of the galaxies. Additionally, we investigate
the evolution in the size distribution of massive quiescent galaxies. We find
that the minimum size growth required for z ~ 2 quiescent galaxies to fall
within the z = 0 size distribution is a factor ~ 2 smaller than the total
median size growth between z ~ 2 and z = 0.
