SPATIALLY RESOLVED EMISSION OF A HIGH-REDSHIFT DLA GALAXY WITH THE KECK/OSIRIS IFU

We present the first Keck/OSIRIS infrared IFU observations of a high-redshift damped Ly alpha (DLA) galaxy detected in the line of sight to a background quasar. By utilizing the Laser Guide Star Adaptive Optics to reduce the quasar point-spread function to FWHM similar to 0 ''.15, we were able to search for and map the foreground DLA emission free from the quasar contamination. We present maps of the H alpha and [O III] lambda lambda 5007, 4959 emission of DLA 2222-0946 at a redshift of z similar to 2.35. From the composite spectrum over the Ha emission region, we measure a star formation rate of 9.5 +/- 1.0 M-circle dot yr(-1) and a dynamical mass of M-dyn = 6.1 Chi 10(9) M-circle dot. The average star formation rate surface density is = 0.55 M-circle dot yr(-1) kpc(-2), with a central peak of 1.7 M-circle dot yr(-1) kpc(-2). Using the standard Kennicutt-Schmidt relation, this corresponds to a gas mass surface density of Sigma(gas) = 243 M-circle dot pc(-2). Integrating over the size of the galaxy, we find a total gas mass of M-gas = 4.2 Chi 10(9) M-circle dot. We estimate the gas fraction of DLA 2222-0946 to be f(gas) similar to 40%. We detect [N II] lambda 6583 emission at 3 sigma significance with a flux corresponding to a metallicity of 75% solar. Comparing this metallicity with that derived from the low-ion absorption gas similar to 6 kpc away, similar to 30% solar, indicates possible evidence for a metallicity gradient or enriched in/outflow of gas. Kinematically, both H alpha and [O III] emission show relatively constant velocity fields over the central galactic region. While we detect some red and blueshifted clumps of emission, they do not correspond with rotational signatures that support an edge-on disk interpretation.