Admin Login • Instructor Login • Student Login

Your Support

Departmental Colloquium

Chasing Shadows: Quasar Absorption Lines as Probes of Galaxy Evolution  
Guest Speaker
Dr. Varsha Kulkarni  
Guest Affiliation
University of South Carolina, Department of Physics and Astronomy  
Dr. Robin Shelton  
Thursday, October 14, 2010 4:00 pm - 5:00 pm  
Physics 202  

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. Fortunately, a very sensitive technique to detect distant galaxies is by means of their "shadows" against the light of bright background sources such as quasars. 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 recently 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, we have recently discovered a new 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 strange galaxies, and why did they get enriched so quickly? We will discuss clues emerging from our imaging/ spectroscopic observations that promise to shed light on several aspects of galaxy evolution.