NOAO >   Observing Info >   Approved Programs >   2003B-0370

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Proposal Information for 2003B-0370


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

CoI: Donald G. York, University of Chicago
CoI: James T. Lauroesch, Northwestern University
CoI: Pushpa A. Khare, Utkal University
CoI: Arlin P. S. Crotts, Columbia University
CoI: Osamu Nakamura, University of Tokyo

Title: The Evolution of Metals and Dust in Damped Lyman-alpha Quasar Absorbers

Abstract: The evolution of metals and dust in galaxies provide important constraints on the cosmic star formation history. Abundances of undepleted elements such as Zn in damped Lyman-alpha (DLA) quasar absorbers probe the metallicity, while ratios such as Cr/Zn or Fe/Zn trace the dust content. Most cosmic chemical evolution models predict the global mean metallicity to increase with time. But it is unclear whether or not DLAs actually show this trend, mainly because of the small number of Zn measurements available at z \lesssim 1.5, which spans ~ 70 % of the cosmic history. The enormous increase in the number of Mg II/DLA absorber detections from the SDSS and HST surveys provides us an opportunity to pin down the cosmic age- metallicity relation to unprecedented accuracy. Since Fall 2002, we have started an abundance survey of z < 1.5 SDSS/HST DLAs at the MMT. With 2 out of 6 nights lost to bad weather, we have observed 12 z < 1.5 DLAs. Here we propose to extend our sample by observing Zn, Cr, Fe, Ni, Mn, Si in 9 more SDSS DLAs with 0.6 < z < 1.5 and Ti, Ca in 3 DLAs at z < 0.6 for which we are obtaining Zn and Cr with HST. We request 3 grey nights with the MMT blue channel spectrograph to achieve the necessary S/N and spectral resolution.


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