We present the results of a 42-orbit Hubble Space Telescope Wide-Field Camera 3 ( HST /WFC3 ) survey of the rest-frame optical morphologies of star forming galaxies with spectroscopic redshifts in the range z = 1.5 - 3.6 .
The survey consists of 42 orbits of F160W imaging covering \sim 65 arcmin ^ { 2 } distributed widely across the sky and reaching a depth of 27.9 AB for a 5 \sigma detection within a 0.2 arcsec radius aperture .
Focusing on an optically selected sample of 306 star forming galaxies with stellar masses in the range M _ { \ast } = 10 ^ { 9 } -10 ^ { 11 } M _ { \odot } , we find that typical circularized effective half-light radii range from \sim 0.7 - 3.0 kpc and describe a stellar mass - radius relation as early as z \sim 3 .
While these galaxies are best described by an exponential surface brightness profile ( Sersic index n \sim 1 ) , their distribution of axis ratios is strongly inconsistent with a population of inclined exponential disks and is better reproduced by triaxial stellar systems with minor/major and intermediate/major axis ratios \sim 0.3 and 0.7 respectively .
While rest-UV and rest-optical morphologies are generally similar for a subset of galaxies with HST /ACS imaging data , differences are more pronounced at higher masses M _ { \ast } > 3 \times 10 ^ { 10 } M _ { \odot } .
Finally , we discuss galaxy morphology in the context of efforts to constrain the merger fraction , finding that morphologically-identified mergers/non-mergers generally have insignificant differences in terms of physical observables such as stellar mass and star formation rate , although merger-like galaxies selected according to some criteria have statistically smaller effective radii and correspondingly larger \Sigma _ { SFR } .