1 March 2001CfA Colloquium


Title: Cosmic Census of AGN and the Growth of Supermassive Black Holes

Speaker: Amy Barger

Abstract: The Chandra X-ray Observatory detects X-rays emitted during the accretion of matter onto supermassive black holes, even when they are highly obscured. A cosmic census of AGN contributing to the X-ray background is nearing completion. Follow-up observations with ground-based telescopes provide new knowledge about distant supermassive black holes. From optical data we find the duration and times of black hole activity. Surprisingly, the duty cycle is about a billion years, and accretion is still occurring at cosmologically recent times. These conclusions challenge conventional wisdom that black hole growth is only associated with host galaxy formation or violent galaxy mergers. With the addition of submillimeter and radio data, we determine bolometric luminosities and estimate black hole masses.

Reference for students:

Barger et al., 2001, "The Nature of the Hard X-Ray Bacground Sources: Optical, Near-infrared, Submillimeter, and Radio Properties", astro-ph/0007175

Mushotzky et al., 2000, "Resolving the Extragalactic Hard X-ray Background", Nature, 404, 459

Barger et al., 2000, "Mapping the Evolution of High-Redshift Dusty Galaxies with Submillimeter Observations of a Radio-Selected Sample", AJ, 119, 2092

Lunch with the students will be on Friday, March 2nd at 12:00 in A-101.