NOAO >   Observing Info >   Approved Programs >   2006A-0477

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Proposal Information for 2006A-0477


PI: Joseph Meiring, University of South Carolina, meiring@physics.sc.edu
Address: Dept. of Physics and Astronomy, 712 Main Street, Columbia, SC 29208, USA

CoI: Varsha P. Kulkarni, University of South Carolina
CoI: Donald G. York, University of Chicago
CoI: Pushpa Khare, Utkal University
CoI: Celine P\'eroux, European Southern Observatory
CoI: James T. Lauroesch, Northwestern University
CoI: Arlin P. S. Crotts, Columbia University
CoI: Osamu Nakamura, University of Nottingham

Title: Element Abundances in Sub Damped Lyman-(alpha) and Dusty Damped Lyman- (alpha) Absorbers: Possible solutions to the ``Missing-Metals Puzzle''

Abstract: Damped Lyman-alpha Absorbers (DLAs) and sub-DLAs in quasar spectra can be used to test model predictions that the global mean interstellar metallicity in galaxies increases with time. Our recent HST, MMT, and VLT data suggest that the DLA global metallicity does not reach the solar level at low redshifts. This ``missing-metals problem'' contradicts the predictions of chemical evolution models based on the cosmic star formation history. We propose to investigate two possible sites for the missing metals, i.e. sub-DLAs and dusty DLAs. We have recently discovered two sub-DLAs with solar or super solar metallicities. If a large number of other sub-DLAs also show high metallicity, they could contribute significantly to the cosmic budget of metals. We request 3 nights with the MMT blue channel spectrograph to study metal abundances in 6 sub-DLAs at 0.7 < z < 1.3 and to search for the 2175 A dust feature. We also request 2 nights with Magellan MIKE to study 5 dusty absorbers toward red quasars and 1 night with Keck HIRESb to study 3 absorbers at z ~ 0.5, the lowest redshift currently accessible. The proposed data will enable accurate determinations of the mean metallicity and dispersion in metallicity in low-z absorbers, help quantify the role of sub-DLAs and dust obscuration effects and greatly increase the low-z high-resolution sample.


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