High-redshift elliptical galaxies: are they (all) really compact?
  We investigate the properties of 12 ultra-massive passively evolving early
type galaxies (ETGs) at z_phot>1.4 in the COSMOS 2 deg^2 field. These 12 ETGs
were selected as pBzKs, have accurate 1.4<= z_phot <=1.7,high Sersic index
profiles typical of ellipticals, no detection at 24 micron, resulting in a
complete ETG sample at M*>2.5x10^11 M_sun (Chabrier IMF). Contrary to previous
claims, the half light radii estimated in very high S/N imaging data from
HST+ACS are found to be large for most of the sample, consistent with local
ellipticals. If the high redshift ETGs with M*<2.5x10^11 M_sun are really small
in size and compact as reported in previous studies, our result may suggest a
"downsizing" scenario, whereby the most massive ETGs reach their final
structure earlier and faster than lower mass ones. However, simulating galaxies
with morphological properties fixed to those of local ETGs with the same
stellar mass show that the few compact galaxies that we still recover in our
sample can be understood in term of fluctuations due to noise preventing the
recovery of the extended low surface brightness halos in the light profile.
Such halos, typical of Sersic profiles, extending even up to 40 kpc, are indeed
seen in our sample.
