Dr. John Moustakas
NYU

University of Florida Astronomy Colloquium - Nov. 29th, 2006

The Star Formation and Chemical Evolution Histories of Galaxies

A predictive theory of galaxy formation remains elusive owing to our poor understanding of star formation, and the effects of star formation on the surrounding interstellar medium ("feedback"). In addition to directly measuring star formation rates, valuable insight into these physical processes can be gleaned by studying the gas-phase abundance of heavy elements. As part of a larger effort to develop quantitative spectral diagnostics of galaxy evolution, I will present some recent results on using the H-alpha and [O II] nebular emission lines as quantitative star formation indicators at both low and high redshift. I will also show some preliminary measurements of the chemical abundance properties of luminous star-forming galaxies at intermediate redshift. At fixed luminosity, we find that star-forming galaxies at z=1 are a factor of two more metal-poor than comparably luminous galaxies today. However, the bulk of this change can be attributed to passive luminosity evolution, indicating that very little chemical enrichment, and therefore star formation, has taken place in massive star-forming galaxies over the past eight billion years.