A Shot in the Dark: A Technique for Locating the Stellar Counterparts of Damped Lyman Alpha Absorbers

Abstract

We present initial results from a Magellan telescope program to image galaxies that give rise to damped Lyman absorbers (DLAs) at 1.63 < z_DLA < 2.37. Our program differs from previous efforts in that we target quasars with intervening Lyman limit systems (LLS) along the line of sight at redshift z_LLS > 3.5. The higher-redshift LLS is applied as a blocking filter to remove the glare of the background quasar at the rest-frame ultraviolet wavelengths of the foreground galaxy. The complete absence of quasar light offers an unimpeded view along the sightline to the redshift of the LLS, allowing an exhaustive search for the DLA galaxy to the sensitivity limit of the imaging data (at or better than 0.25L*). In both of our pilot fields (PKS2000-330, z_DLA=2.033 and SDSS0322-0558, z_DLA=1.69), we identify an L* galaxy within 5&#34; of the sightline which has optical colors consistent with star-forming galaxies at z~2. We examine the correlation between absorption-line properties and galaxy luminosity and impact distance, and compare the high-redshift galaxy and absorber pairs with those known at z<1.