NOAO >   Observing Info >   Approved Programs >   2013B-0525

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Proposal Information for 2013B-0525


PI: Varsha P. Kulkarni, University of South Carolina, kulkarni@sc.edu
Address: Dept. of Physics and Astronomy, 712 S. Main Street, Columbia, SC 29208, USA

CoI: Debopam Som, University of South Carolina
CoI: Celine Peroux, Laboratoire d’Astrophysique de Marseille
CoI: Donald G. York, University of Chicago

Title: Prospecting for rare metals in the distant universe: The Chemical Composition of Super-damped Lyman-alpha Absorbers

Abstract: Damped Lyman-alpha absorbers (DLAs) observed in the spectra of quasars dominate the mass density of neutral gas in the universe. While DLAs with very high H I column densities were missing from earlier studies, recently some ``super-DLAs" with H I column densities exceeding 5 \times 10^21 cm^-2 have been discovered in the SDSS III DR9. These super-DLAs are especially interesting, because they appear to be moderately enriched chemically, and may contain substantial amount of molecular gas. Moreover, at least some of them may arise in galaxies with substantial star formation rates, as indicated by detection of emission lines from some of them. Here we propose to obtain Keck ESI spectra of 9 such super-DLAs at 2 < z < 3. Our science goals are to (1) determine abundances of a large range of elements, including rare elements (e.g., Cl, V, Cu, Co, Ga), to obtain new nucleosynthetic constraints in young galaxies, (2) constrain the dust content using relative abundances, (3) determine the electron density, (4) determine the star formation rate (SFR) and SFR surface density, and (5) search for molecules, in these unique absorbers in the distant universe. Keck ESI is needed to efficiently obtain medium-resolution spectra of these super-DLAs with optically faint background quasars.


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