Abstract
We present the first Keck/OSIRIS infrared IFU observations of a high redshift
damped Lyman-alpha (DLA) galaxy detected in the line of sight to a background
quasar. By utilizing the Laser Guide Star Adaptive Optics (LGSAO) to reduce the
quasar PSF to FWHM~0.15 arcsec, 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 OIII $łambda$ 5007, 4959 emission of DLA 2222-0946
at a redshift of z ~ 2.35. From the composite spectrum over the H-alpha
emission region we measure a star formation rate of 9.5 $\pm$ 1.0 M$_ødot$
year$^-1$ and a dynamical mass, M$_dyn$ = 6.1 x 10$^9$ M$_ødot$. The
average star formation rate surface density is < \Sigma_SFR > = 0.55
M$_ødot$ yr$^-1$ kpc$^-2$, with a central peak of 1.7 M$_ødot$
yr$^-1$ kpc$^-2$. Using the standard Kennicutt-Schmidt relation, this
corresponds to a gas mass surface density of $\Sigma_gas$ = 243 M$_ødot$
pc$^-2$. Integrating over the size of the galaxy we find a total gas mass of
M$_gas$ = 4.2 x 10$^9$ M$_ødot$. We estimate the gas fraction of DLA
2222-0946 to be $f_gas$ ~ 40%. We detect NII$łambda$6583 emission at 2.5
sigma significance with a flux corresponding to a metallicity of 75% solar.
Comparing this metallicity with that derived from the low-ion absorption gas ~6
kpc away, ~30% solar, indicates possible evidence for a metallicity gradient or
enriched in/outflow of gas. Kinematically, both H-alpha and OIII 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.
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