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T. C. Urrutia (UC Davis, IGPP LLNL), M. Lacy (SIRTF Science Center), R. H. Becker (UC Davis, IGPP LLNL), L. J. Storrie-Lombardi (SIRTF Science Center), M. D. Gregg (UC Davis, IGPP LLNL)
We present results of an ongoing campaign to discover damped Ly\alpha (DLA) absorption systems at redshifts z < 1.5. We selected quasar absorption systems from the FIRST Bright Quasar Survey with equivalent widths for FEII 2600 > 1 Å and took follow-up spectra of some of these with the Hubble Space Telescope (HST). So far, 6 new low redshift DLAs have been discovered in spectra of 21 candidate absorption systems. This is fewer than predicted by previous studies (Rao & Turnshek 2000). Nevertheless, all of our systems show a column density NHI \ge 1019 cm-2.
We have made different high resolution composite spectra of 45 possible DLAs, revealing much weaker absorption lines. Metallicity measurements in the composite spectra show that the cosmic neutral gas-phase metallicity traced by the DLAs is larger at lower redshift.
We have also identified galaxies near 5 quasars which are at the redshift of DLA systems of the quasars. The spectra suggest that these are star forming galaxies and they have a mean luminosity lower than the break in the local galaxy luminosity function (sub-L*).
This work is supported under grant AST-00-98355 from the NSF.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.