Abstract

Spectroscopic+photometric redshifts, stellar mass estimates, and rest-frame colors from the 3D-HST survey are combined with structural parameter measurements from CANDELS imaging to determine the galaxy size–mass distribution over the redshift range 0 3 × 109 M☉, and steep, , for early-type galaxies with stellar mass >2 × 1010 M☉. The intrinsic scatter is ≲0.2 dex for all galaxy types and redshifts. For late-type galaxies, the logarithmic size distribution is not symmetric but is skewed toward small sizes: at all redshifts and masses, a tail of small late-type galaxies exists that overlaps in size with the early-type galaxy population. The number density of massive (∼1011 M☉), compact (Reff < 2 kpc) early-type galaxies increases from z = 3 to z = 1.5–2 and then strongly decreases at later cosmic times.