Physical Processes of Galaxy Evolution

University Of Texas At Austin, Austin TX

Investigators

Abstract

The Universe is in transition from early times when galaxies formed and evolved by the growth, hierarchical clustering, and merging of primordial density fluctuations to a future when galaxies will evolve mainly in isolation by slow processes. Secular evolution is the slow rearrangement of energy and mass that results from interactions of stars and gas with collective phenomena like bars and tri-axial dark halos. The Principal Investigator takes a quantitative approach to galaxy evolution by investigating the relative importance of secular vs. hierarchical merging through determining the relative frequency of central bulges and pseudo-bulges (high-density stellar components) in several carefully chosen samples of galaxies. He will study the surface brightness and color distribution of ~1000 galaxies from the SDSS (Sloan Digital Sky Survey) data, and study low-luminosity objects that are rapidly rotating and nearly isotropic in velocity distributions as well as giant objects that are slowly rotating, anisotropic, and moderately tri-axial. Observations will include photometry at the MacDonald Observatory 0.8m telescope and spectroscopy at the Hobby-Eberly telescope. Comparing the observations with simulations will reveal details of the formation processes that will help us understand high-redshift galaxies. The Principal Investigator will collaborate with the McDonald Observatory Education and Outreach Office to produce five radio programs per year that communicate the excitement and results of this research program to the public. The English-language "StarDate" version has an audience of more than two million people, and the Spanish "Universo" version reaches approximately 250,000 people. The team will concurrently write two popular-level articles for Stardate magazine, which has a circulation of about 10,000 subscribers. For professional astronomers, the data products from this program will be made available online.