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 Upcoming Talks        Past Talks        Calendar View

Departmental Colloquium


Quasar Winds

Dr. Pat Hall
Princeton University / P. Universidad Catolica de Chile

Time
 
Mon. January 6, 2003     2:30 PM     STIRLING C

Abstract
 

Quasars, powered by accretion onto supermassive black holes at the centers of galaxies, are among the most luminous objects in the universe. Their spectra provide us with a wealth of insight into gas physics under a wide range of different conditions. In particular, about 15 percent of quasars, the Broad Absorption Line quasars, show absorption from gas with blueshifted outflow velocities of up to 20 percent of lightspeed and with mass loss rates comparable to the accretion rates required to power quasars. The Sloan Digital Sky Survey is, for the first time, providing a sample of BAL quasars large enough to begin constraining models for their origin(s) and evolution. For example, do all quasars have BAL winds with an average global covering factor of 15 percent, or do all quasars go through a 100 percent covering BAL phase that lasts 15 percent of the typical quasar lifetime? I will present an overview of how discovery and followup of SDSS BAL quasars is beginning to answer these and other questions about these intriguing objects.

Dr. Pat Hall is a candidate for the Observational-Experimental Astronomer position in the Department of Physics.

Refreshments will be available in the lounge after the talk.

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