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Physics Colloquium: How Long do Quasars Shine?
Start Date: 11/29/2018Start Time: 3:30 PM
End Date: 11/29/2018End Time: 4:30 PM

Event Description

Joseph F. Hennawi, PhD, University of California, Santa Barbara

Luminous quasars are believed to be the progenitors of the supermassive black holes observed ubiquitously at the centers of all massive galaxies. But half a century after their discovery, we are still in the dark about how these black holes actually formed. Our ignorance largely results from the long expected timescale for supermassive black hole growth of 45 million years — far longer than humans have been conducting astronomical observations.

A holy grail would thus be a direct measurement of the lifetimes of luminous quasars, shedding light on the physical mechanisms responsible for fueling black hole growth, and how the back-reaction of this growth might influence how galaxies form. I will show how observations of diffuse intergalactic gas in the environs of luminous quasars can be used to chronicle the history of quasar emission on timescales from kiloyears to gigayears. I will also discuss how these same observations can be used to constrain the timing of an important phase transition in our Universe's history.

Contact Information:
Name: Professor Gordon Richards
Email: gtr@physics.drexel.edu
Disque Hall, Room 919, 32 South 32nd Street, Philadelphia, PA 19104
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