Grant: $264,491 - National Science Foundation - Aug. 20, 2009
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Award Description: Damped and Sub-damped Lyman-alpha Absorbers: What Are They, and What Do They Tell Us About Galaxy Evolution? PROJECT SUMMARY The evolution of galaxies and the production of chemical elements in the universe are fun- damental issues in astrophysics and cosmology. As the cycle of star birth and death progresses,the mean interstellar metallicity of galaxies is expected to rise, reaching a near-solar level by the present epoch. A powerful tool for tracing galaxy evolution is provided by the damped Lyman- (DLA) and sub-DLA absorbers that lie along the sightlines to quasars. Historically, sub-DLAs have been largely ignored in previous studies due to their lower H I content, and most measurements have focussed on DLAs. These DLA observations appear to contradict the predictions of most chemical evolution models: DLA metallicities and star formation rates (SFRs) stay far below model predictions, and show relatively little evolution over 70% of the age of the universe.We have recently uncovered a highly enriched population of sub-DLA absorbers. These data suggest that, in fact, the sub-DLAs may be the sites of most of the action` related to star formation and chemical enrichment. Here we propose to use sub-DLAs and DLAs as probes of galaxy populations and large-scale structure in the distant universe, combining high-resolution spectroscopy, adaptive optics (AO) imaging and integral eld spectroscopy (IFS). This strategy will address many exciting questions and enable us to make the following important contributions: (1) We will double the existing sub-DLA abundance samples and thus determine the metallicity evolution of sub-DLAs to signicantly greater accuracy. (2) Our AO/IFS studies will yield morphologies, impact parameters, luminosities, and emission-line metallicities of the underlying galaxies. (3) The proposed data will allow us to examine what factors (e.g., the mass-metallicity relation,metallicity gradients, galactic outows) drive the observed trends in absorber metallicities. (4) We will determine SFRs in absorber galaxies from emission lines in our IFS data and from C II absorption lines. This will help clarify where absorbers lie in the cosmic star formation history. (5) We will use spectra of binary and gravitationally lensed quasars that provide multiple sightlines through intervening absorbers to determine the sizes and structures of the absorbers. (6) Our studies will help to understand whether sub-DLAs and DLAs may be the progenitors of early-type and late-type galaxies, and whether their properties reect down-sizing in galaxies. Intellectual Merit : Our study will represent the first step toward etablishing a uniform statistically signicant sample of gas-rich galaxies with accurately determined metallicities over a signicant cosmic time interval. The transformative nature of this research arises from the fact that this project brings together the synergies of absorption line chemistry, galaxy imaging, and gravitational lensing, and will provide fundamental tests of galaxy evolution models. Our research will utilize new data to be obtained at state-of-the-art facilities that we have already been using (Gemini, Keck, VLT, Magellan, MMT). We have extensive experience in this field and have obtained 2=3 of the existing abundance data for z < 1:5 and the first AO images of the absorbers. We are thus uniquely qualifed to carry out the proposed work. Broader Impact: Our work will provide educational benefits through research training of graduate and undergraduate students at the Univ. of South Carolina. The PI will enhance our introductory astronomy courses which currently enroll >2000 undergraduates each year, and develop new graduate/undergraduate courses in extragalactic astronomy and cosmology; she has already developed 3 such courses with prior NSF support. The PI is involved in extensive outreach activities through USC Melton Observatory and South Carolina State Museum. Finally, our team includes several women an
Project Description: As defined in the Award Description field.
Jobs Summary: Graduate Research Assistant (Total jobs reported: 1)
Project Status: Less Than 50% Completed
This award's data was last updated on Aug. 20, 2009. Help expand these official descriptions using the wiki below.