The Sloan Digital Sky Survey Damped Lyα Survey: Data Release 1

Abstract

ABSTRACTWe present the results from an automated search for damped Lyα (DLA) systems in the quasar spectra of Data Release 1 from the Sloan Digital Sky Survey (SDSS‐DR1). At z ≈ 2.5, this homogeneous data set has greater statistical significance than the previous two decades of research. We derive a statistical sample of 71 DLA systems (>50 previously unpublished) at z>2.1 and measure H i column densities directly from the SDSS spectra. The number of DLA systems per unit redshift is consistent with previous measurements, and we expect our survey has more than 95% completeness. We examine the cosmological baryonic mass density of neutral gas, Ωg, inferred from the DLA systems from the SDSS‐DR1 survey and a combined sample drawn from the literature. Contrary to previous results, the Ωg values do not require a significant correction from Lyman limit systems at any redshift. We also find that the Ωg values for the SDSS‐DR1 sample do not decline at high redshift, and the combined sample shows a (statistically insignificant) decrease only at z>4. Future data releases from SDSS will provide the definitive survey of DLA systems at z ≈ 2.5 and will significantly reduce the uncertainty in Ωg at higher redshift.