Research on AGN

I have specialized in studies of AGN ever since my graduate studies at Caltech during 1968-1972. Following my early work on the emission lines of Seyfert galaxies, including photoionization modeling, I branched out in two main directions: (1) accretion disk models for the energy source in AGN, and (2) photoionization modeling of H II regions (discussed on a separate page).

A long standing interest has been the question of what AGN disks should look like. I have concentrated on the thermal emission from accretion disks, including the energy distribution and polarization. Recently I have been particularly interested in the strong polarization observed by HST in the Lyman continuum of some QSOs.

I am also continuing work on the broad absorption lines (BALs) of QSOs. I am a member of a team led by Dr. Vesa Junkkarinen of UCSD to obtain HST spectra of a sample of BAL QSOs.

February 23, 2000
Department of Astronomy
UT Austin
Austin TX 78712