The SINS/zC-SINF Survey of z~2 Galaxy Kinematics: Rest-frame Morphology, Structure, and Colors from Near-infrared Hubble Space Telescope Imaging

We present the analysis of HST \(J\)- and \(H\)-band imaging for 29 galaxies on the star-forming main sequence at \(z\sim2\), which have Adaptive Optics VLT SINFONI integral field spectroscopy from our SINS/zC-SINF program. The SINFONI H\(\alpha\) data resolve the on-going star-formation and the ionized gas kinematics on scales of \(1-2\) kpc; the near-IR images trace the galaxies' rest-frame optical morphologies and distributions of stellar mass in old stellar populations at a similar resolution. The global light profiles of most galaxies show disk-like properties well described by a single Sérsic profile with \(n\sim1\), with only \(\sim15%\) requiring a high \(n>3\) Sérsic index, all more massive than \(10^{10}M_\odot\). In bulge+disk fits, about \(40%\) of galaxies have a measurable bulge component in the light profiles, with \(\sim15%\) showing a substantial bulge-to-total ratio \(B/T\ge0.3\). This is a lower limit to the frequency of \(z\sim2\) massive galaxies with a developed bulge component in stellar mass because it could be hidden by dust and/or outshined by a thick actively star-forming disk component. The galaxies' rest-optical half-light radii range between \(1-7\) kpc, with a median of 2.1 kpc, and lie slightly above the size-mass relation at these epochs reported in the literature. This is attributed to differences in sample selection and definitions of size and/or mass measurements. The \((u-g)_{rest}\) color gradient and scatter within individual \(z\sim2\) massive galaxies with \(\ge10^{11}M_\odot\) are as high as in \(z=0\) low-mass, late-type galaxies, and are consistent with the high star-formation rates of massive \(z\sim2\) galaxies being sustained at large galactocentric distances.