Chasing Shadows: Quasar Absorption Lines as Probes of Galaxy Evolution
Varsha Kulkarni

The evolution of galaxies and the cosmic history of element production are fundamental themes in modern astrophysics and cosmology. However, the light emitted by distant galaxies is often too faint to allow detailed studies. Absorption lines in quasar spectra can be used to probe interstellar gas in galaxies at various stages of evolution, and thus provide powerful probes of the history of star formation and chemical enrichment in galaxies. Using this technique, we uncovered a "missing metals problem'' in low-redshift galaxies, i.e. a discrepancy between the observed amount of "metals" and the amount predicted by the chemical evolution models. On the other hand, there appears to be a population of galaxies with very high levels of "metals", including some that had reached several times the Sun's metallicity 7-10 billion years ago. What are these galaxies, and why did they get enriched so quickly? How vigorously did star formation take place in these distant galaxies, and how were they affected by inflows and outflows of gas? We will discuss clues emerging from imaging/spectroscopic observations that promise to shed light on various aspects of galaxy evolution.