NOAO >   Observing Info >   Approved Programs >   2003B-0062

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Proposal Information for 2003B-0062


PI: David Turnshek, University of Pittsburgh, turnshek@pitt.edu
Address: Department of Physics and Astronomy, 3941 O'Hara Street, Pittsburgh, PA 15260, USA

CoI: Sandhya Rao, University of Pittsburgh

Title: The Kinematics of the Neutral Gas in Low-Redshift Damped Lyman-Alpha Galaxies

Abstract: The high-redshift (z>1.7) damped Ly(alpha) (DLA) absorbers seen in QSO spectra represent neutral gas that is involved in the early stages of galaxy formation. The kinematic properties of this gas can be probed by observing the metal lines of the DLA system at high resolution. This provides a sensitive diagnostic among competing models of galaxy formation (e.g. monolithic collapse of gas into centrifugally supported disks versus modern hierarchical models of galaxy formation), especially if the evolution of the kinematic properties of the neutral gas could be followed to low redshift. However, due to the lack of a sufficient number of DLA absorbers at low redshift until just recently, it has not been possible to obtain low-redshift observations that can be used to make kinematic-based tests of these models. Here we propose to use HET-HRS to do this. We will observe CaII metal-line absorption in 11 QSOs containing 12 DLA absorbers with z<0.9. This low-redshift dataset will be much more valuable than the comparable high-redshift dataset which exists. This is because there are identifications for the low-redshift DLA galaxies and corresponding information on their impact parameters and orientations, unlike the situation at high redshifts. Thus, these low-redshift observations will provide important tests of galaxy formation models. \bf Note: Our initial proposal was submitted in March 2002. We asked for and were allocated 2 nights, but noted that 2 additional nights would be needed to observe the entire sample. Given the performance of HET-HRS so far (see Technical Description), we now estimate that nearly 4 additional nights will be needed, but only 2 are requested here.


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