BEGIN:VCALENDAR VERSION:2.0 CALSCALE:GREGORIAN PRODID:UW-Madison-Physics-Events BEGIN:VEVENT SEQUENCE:0 UID:UW-Physics-Event-2107 DTSTART:20110201T213000Z DTEND:20110201T223000Z DTSTAMP:20260420T134614Z LAST-MODIFIED:20110128T150700Z LOCATION:4421 Sterling Hall SUMMARY:How do Galaxies get their Gas?\, SPECIAL ASTRONOMY TALK\, Dusa n Keres\, UC Berkeley DESCRIPTION:Most galaxies are actively star forming at all epochs. How ever\, observations of dense\, galactic gas indicate that\, at any epo ch\, there is not enough gas in galaxies to support evolution of star formation activity over time. This suggests that galactic gas is being replenished from the intergalactic medium.<\;br>\;

\n I u se fully cosmological hydrodynamic simulations to study the gas supply into galactic component from high redshift to present. At high redshi ft &\;quot\;smooth&\;quot\; infall of cold filamentary gas domin ates the gas supply of all galaxies. This &\;quot\;cold mode accret ion&\;quot\; is unlike the accretion in the standard model of galax y formation in which cooling of the hot halo atmospheres is a source o f gas supply to galaxies. Cold mode accretion is a major driver of ver y active star formation of high-z galaxies enabling such activity to p roceed for a significant fraction of the Hubble time. Gas accretion ra tes at a given halo and galaxy mass decrease with time\, causing the d rop in star formation rates. At low redshift hot virialized gas can co ol in some of the halos\, but cold gaseous clouds that form from infal ling filaments can dominate gas supply in galaxies such as Milky Way.& lt\;br>\;

\n In this talk I will describe properties\, phy sics and consequences of cold gas accretion as well as predictions for the observational probes of cold halo gas that can provide strong co nstraints on the models. I will also discuss remaining open questions and future directions in the studies of galactic gas accretion\, inclu ding additional physical processes\, new computational methods and obs ervations with upcoming facilities.&\;quot\;<\;br>\;

\n URL:https://www.physics.wisc.edu/events/?id=2107 END:VEVENT END:VCALENDAR