Keck/OSIRIS IFU Detection of a z $\sim$ 3 Damped Lyman Alpha Host Galaxy

Abstract

We present Keck/OSIRIS infrared IFU observations of the $z = $ 3.153 sub-DLA DLA2233+131, previously detected in absorption to a background quasar and studied with single slit spectroscopy and PMAS integral field spectroscopy (IFU). We used the Laser Guide Star Adaptive Optics (LGSAO) and OSIRIS IFU to reduce the point-spread function of the background quasar to FWHM$\sim$0.15 arcseconds and marginally resolve extended, foreground DLA emission. We detect [OIII]$\lambda$5007 emission with a flux F$^{[OIII]\lambda5007}$ = $(2.4\pm0.5)\times10^{-17}$ erg s$^{-1}$ cm$^{-2}$, as well as unresolved [OIII]$\lambda$4959 and H$\beta\lambda$4861 emission. Using a composite spectrum over the emission region, we measure dynamical mass $\sim$ $3.1\times10^9$ M$_{\odot}$. We make several estimates of star formation rate using [OIII]$\lambda$5007 and H$\beta\lambda$4861 emission, and measure a star formation rate of $\sim$ $7.1- 13.6$ M$_{\odot}$ yr$^{-1}$. We map [OIII]$\lambda$5007 and H$\beta\lambda$4861 emission and the corresponding velocity fields to search for signs of kinematic structure. These maps allow for a more detailed kinematic analysis than previously possible for this galaxy. While some regions show slightly red and blue-shifted emission indicative of potential edge-on disk rotation, the data are insufficient to support this interpretation.