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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-4517
DTSTART:20170330T203000Z
DTEND:20170330T220000Z
DTSTAMP:20260419T060246Z
LAST-MODIFIED:20170316T131209Z
LOCATION:4421 Sterling Hall\, Coffee and Cookies 3:30 pm\, Talk begins
  3:45 pm
SUMMARY:Towards understanding the inefficiency of star formation in ga
 laxies\, Astronomy Colloquium\, Andrey Kravtsov\, The University of Ch
 icago
DESCRIPTION:One of the long-standing puzzles of galaxy formation is th
 e global inefficiency with which galaxies convert baryonic matter avai
 lable to them into stars. This inefficiency is manifested in 1) the fa
 ct that ratio of baryon mass observed within galaxies to the total inf
 erred mass of their host halos is much smaller than the universal bary
 on fraction and 2) the fact that galaxies convert their observed gas i
 nto stars on ~2-10 Gyr time scale (gas depletion time)\, which is much
  longer than any dynamical time scale within galaxies.<br>
\n<br>
\nI 
 will review recent progress in galaxy formation simulations due to imp
 rovements in treatment of stellar feedback and star formation\, which 
 sheds light into the 1st aspect of inefficiency.  I will present a new
  model\, in which local star formation efficiency is modelled "on the 
 fly" using a turbulence-based subgrid model based on results of high-r
 esolution simulations of molecular clouds. The model predicts a wide v
 ariation of star formation efficiency per free fall time at odds with 
 the usual assumption of constant efficiency. At the same time\, our mo
 del predicts distribution of star formation rates in broad agreement w
 ith observations of both local and resolved extragalactic GMCs. I will
  show that with realistic implementation of stellar feedback this mode
 lling can reproduce the basic properties of star formation and the Ken
 nicutt-Schmidt relation in galaxies\, such as the Milky Way. Finally\,
  using insights from such simulations I will present a simple model ex
 plaining why star formation in galaxies is inefficient and depletion t
 imes are long. 
URL:https://www.physics.wisc.edu/events/?id=4517
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