Date of Award

1-1-2012

Document Type

Campus Access Dissertation

Department

Physics and Astronomy

Sub-Department

Physics

First Advisor

Varsha P Kulkarni

Abstract

The question of how galaxies evolve is a difficult one to answer. By studying galaxies hosting Damped (DLA) and sub-Damped Lyman-alpha (sub-DLA) systems, we hope to shed some light on the subject. DLA and sub-DLA systems contain the vast majority of neutral gas in the universe, making them ideal candidates for studies of primordial gas. However, it is unclear how these absorption systems relate to present day galaxies. Observations of these systems detected through absorption in background quasar spectra indicate the DLAs are metal poor and slowly evolving while their counterparts, the sub-DLAs, are highly enriched. In order to determine the relationship between galaxies detected in absorption and normal galaxies, we compile a sample of low redshift quasar galaxy pairs (QGP) detected in emission in quasar spectra. These emission detected galaxies are searched for absorption features that may indicate a connection to higher redshift galaxy absorption systems, including DLAs and sub-DLAs. While the roles of spectroscopy and imaging play equal parts in determining characteristics of these systems, focus here is placed on the broad-band imaging aspect, used to locate absorption host galaxies and determine their photometric properties. These properties can then be compared to the known properties of galaxies at other epochs. The role of the Sloan Digital Sky Survey has been paramount in this study. Presented here are two sets of data: high metallicity DLA and sub-DLA absorption systems at z>0.4 and quasar-galaxy pairs selected in emission from the Sloan Digital Sky Survey at z0.4 sample of DLAs and sub-DLAs. Morphologically, those galaxies selected by emission naturally tend to be late-type, while our sample of DLAs and sub-DLAs appears to be primarily early-type.

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