High Resolution Studies of Lensed z~2 Galaxies: Kinematics and Metal Gradients

<p>We use the OSIRIS integral field unit (IFU) spectograph to secure spatially-resolved strong emission lines of 15 gravitationally-lensed star-forming galaxies at redshift z~2. With the aid of gravitational lensing and Keck laser-assisted adaptive optics, the spatial resolution of these sub-luminous galaxies is at a few hundred parsecs. First, we demonstrate that high spatial resolution is crucial in diagnosing the kinematic properties and dynamical maturity of z~2 galaxies. We observe a significantly lower fraction of rotationally-supported systems than what has been claimed in lower spatial resolution surveys. Second, we find a much larger fraction of z~2 galaxies with weak metallicity gradients, contrary to the simple picture suggested by earlier studies that well-ordered rotation develops concurrently with established steep metal gradients in all but merging systems. Comparing our observations with the predictions of hydronamical simulations, strong feedback is likely to play a key role in flattening metal gradients in early star-forming galaxies.