15 March 2001CfA Colloquium

Title: Quasar Absorption Lines: Observations with Chandra, the MMT and Hubble

Speaker: Jill Bechtold

Abstract: We analyzed quasar absorption line spectra obtained with the Faint Object Spectrograph, from the Hubble Space Telescope Archives. The sample is about four times larger than the Quasar Absorption Line Key Project sample obtained by Bahcall and collaborators. The larger sample confirms many of their results, and allows us to investigate a number of new issues. We combine the HST data with our ground-based spectroscopy of quasars at the MMT to determine the evolution of the Lyman alpha forest, the clustering of absorption lines, the evolution of the ionizing UV background, and the distribution of C IV in the Milky Way. Finally, this sample contains interesting objects which are well-suited for detailed study at other wavelengths. We report one such study, in which we have used ACIS aboard Chandra to detect absorption associated with a damped Lyman alpha quasar absorber.

Reference for students:

Lunch with the students will be on Friday, March 16th at 12:00 in A-101.