Constraints on the Assembly and Dynamics of Galaxies: I. Detailed
  Rest-frame Optical Morphologies on Kiloparsec-scale of z ~ 2 Star-forming
  Galaxies
  We present deep and high-resolution HST/NIC2 F160W imaging at 1.6micron of
six z~2 star-forming galaxies with existing near-IR integral field spectroscopy
from SINFONI at the VLT. The unique combination of rest-frame optical imaging
and nebular emission-line maps provides simultaneous insight into morphologies
and dynamical properties. The overall rest-frame optical emission of the
galaxies is characterized by shallow profiles in general (Sersic index n<1),
with median effective radii of ~5kpc. The morphologies are significantly clumpy
and irregular, which we quantify through a non-parametric morphological
approach, estimating the Gini (G), Multiplicity (Psi), and M_20 coefficients.
The strength of the rest-frame optical emission lines in the F160W bandpass
indicates that the observed structure is not dominated by the morphology of
line-emitting gas, and must reflect the underlying stellar mass distribution of
the galaxies. The sizes and structural parameters in the rest-frame optical
continuum and Halpha emission reveal no significant differences, suggesting
similar global distributions of the on-going star formation and more evolved
stellar population. While no strong correlations are observed between stellar
population parameters and morphology within the NIC2/SINFONI sample itself, a
consideration of the sample in the context of a broader range of z~2 galaxy
types indicates that these galaxies probe the high specific star formation rate
and low stellar mass surface density part of the massive z~2 galaxy population,
with correspondingly large effective radii, low Sersic indices, low G, and high
Psi and M_20. The combined NIC2 and SINFONI dataset yields insights of
unprecedented detail into the nature of mass accretion at high redshift.
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