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RASC Mississauga Centre Meeting May 23

  • University of Toronto Mississauga 3359 Mississauga Road Mississauga Ontario L5L 1C6 (map)

The May 23 meeting of the RASC Mississauga Centre will feature a talk on Quasars and Black Holes.

Gas Falling Into Black Holes: A Surprising Discovery

Speaker: Professor Pat Hall, York University 

A black holes is inferred to exist at the center of every massive galaxy, including our own Milky Way. We cannot see such a black hole directly, but we can see light from hot gas orbiting the black hole. This gas forms a disk larger than the Earth's orbit around the Sun and hotter than the surface of the Sun, putting out enough light to be seen across the universe; we call this light a quasar.

For 45 years we have known that some quasars have part of their light absorbed by gas streaming AWAY from the black holes, in winds lifted from the surface of these disks. A few years ago, I discovered some cases of absorption which may come from gas streaming INTO the black holes. But it may be difficult to explain the speeds at which the gas appears to be falling into the black holes in these quasars; they may instead be cases of winds in systems with two black holes orbiting each other!

An artist's impression of a supermassive black hole, with matter falling into it rotating as a disk heating up in its centre, and two jets of relativistic particles emitted along the axis. Some gas and stars from the surrounding galaxy are visible in the background. Artwork courtesy University of Toronto / Dunlap Institute

An artist's impression of a supermassive black hole, with matter falling into it rotating as a disk heating up in its centre, and two jets of relativistic particles emitted along the axis. Some gas and stars from the surrounding galaxy are visible in the background. Artwork courtesy University of Toronto / Dunlap Institute

Pat Hall is an astronomer and Associate Professor in York University's Department of Physics and Astronomy.  Born in California to Canadian parents, he double-majored in Physics and Astronomy at U. C. Berkeley and obtained a doctorate in astronomy at U. Arizona (even if it took 7 and a half years).  He then studied galaxies as a postdoctoral fellow at  U. Toronto and quasars as a joint postdoc at Princeton and the Universidad Catolica de Chile before joining the faculty at York.

He divides his work time between research on quasars (and anything else astronomical that catches his fancy), teaching astronomy, and outreach. Once in a while he blogs at pathallresearch.blogspot.ca

The meeting will be held from 8:00 to 10:00 p.m. at The University of Toronto,Mississauga Campus, 3359 Mississauga Road in lecture hall SE2082 in the William Davis Building. The meeting is open to the public and is free.  

 Enter off of Mississauga Road. Park in lot 4 or the parkade, across from the fitness centre south of theDavis Building. Enter through the Fitness centre, walk up the stairs untilyou reach the main corridor then turn right. (If you need an elevator,follow the corridor to the right of the stairs, then go up to the mainfloor.) Look for the Mississauga Centre sign in front of the lecture room. For directions see this online map.

Post meeting plans: we usually continue the discussion post-meeting at a local bar – please join us!