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.

Another interest is observational signatures of recoiling black holes. The paper "Powerful Flares from Recoiling Black Holes in Quasars" (G. A. Shields and E. W. Bonning 2008, ApJ 682:758) discusses a numerical simulation of an accretion disk disrupted by a recoiling black hole. An animation of the numerical simulation is here.

My recent paper "A Captured Runaway Black Hole in NGC 1277?" (Shields and Bonning 2013, ApJ 772, L5) is described in an article in Science News by Andrew Grant available here.

July 13, 2013
Department of Astronomy
UT Austin
Austin TX 78712