THE MASS-RADIUS RELATION FOR STAR-FORMING GALAXIES AT z ∼ 1.5-3.0

We present early results from a Hubble Space Telescope WFC3/IR imaging survey of star-forming galaxies in the redshift range 1.5 < z < 3.0. When complete, this survey will consist of 42 orbits of F160W imaging distributed amongst 10 survey fields on the line of sight to bright background QSOs, covering 65 arcmin(2) to a depth of 27.9 AB with a point-spread function FWHM of 0.'' 18. In this contribution, we use a subset of these fields to explore the evolution of the galactic stellar mass-radius relation for a magnitude-limited sample of 102 spectroscopically confirmed star-forming galaxies (< SFR > similar to 30 M-circle dot yr(-1)) with stellar mass M-* similar to 10(10) M-circle dot. Although the light profile of these galaxies often has an irregular, multi-component morphology, it is typically possible to describe the brightest component with a Sersic profile of index n similar to 1. The circularized half-light radius r(e) of the brightest component is on average < r(e)> = 1.66 +/- 0.79 kpc (i.e., similar to 50%-70% the size of local late-type galaxies with similar stellar mass), consistent with recent theoretical models that incorporate strong feedback from star-forming regions. The mean half-light radius increases with stellar mass and, at fixed stellar mass, evolves with cosmic time as similar to(1 + z)(-1.42), suggesting that high-redshift star-forming galaxies may evolve onto the local stellar mass-radius relation by redshift z similar to 1.