The Sloan Digital Sky Survey damped Lyα survey: data release 1.
PROCHASKA J.X. and HERBERT-FORT S.
Abstract (from CDS):
We 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50 previously unpublished) at z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 Ωgvalues do not require a significant correction from Lyman limit systems at any redshift. We also find that the Ωgvalues 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 Ωgat higher redshift.