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SUMMARY:Star Formation\, Feedback\, and Cosmic Evolution: A Modern Primer 
 - Eve Ostriker (Princeton University)
DTSTART:20240312T160000Z
DTEND:20240312T170000Z
UID:TALK212170@talks.cam.ac.uk
CONTACT:Steven Brereton
DESCRIPTION:The cosmic history of galaxy formation is the history of star 
 formation writ large.  While the contents of the universe are mostly invis
 ible and interact with baryons only weakly\, a wide array of physical proc
 esses affect evolution of the observable baryons.  Some of the most import
 ant processes involve coupling between stellar and gaseous components\, si
 nce massive stars are the primary energy source in the interstellar medium
  (ISM)\, circumgalactic medium (CGM)\, and intergalactic medium (IGM). The
  majority of stellar energy — including UV radiation\, winds\, and super
 novae — is returned rapidly after a given population of stars forms\, an
 d is therefore collectively termed “star formation feedback.”  Because
  the state of the ISM determines the star formation rate\, and stellar fee
 dback determines the ISM state\, quantifying how this co-regulation works 
 is crucial to theoretical modeling.  The need to quantify feedback respons
 es also extends to galaxy formation theory on larger scales\, where galact
 ic winds driven by feedback heat and add metals to the CGM\, thereby regul
 ating the accretion that replenishes the ISM\, and where escaping stellar 
 UV ionizes the IGM.   Because the observational characterization of galaxi
 es — both near and far — relies on emission lines and infrared continu
 um from gas and dust subject to photoheating and photochemistry from starl
 ight\, quantitative interpretation of observations also relies on calibrat
 ion using physical models that accurately represent radiative transfer in 
 complex environments.   In this lecture\, I will review current theory of 
 the physics of feedback\, showcasing results from state-of-the-art\, high-
 resolution numerical radiation-magnetohydrodynamic simulations that direct
 ly follow multiphase ISM evolution including the effects of UV radiation\,
  stellar winds\, and supernovae.   These simulations\, on both scales of i
 ndividual star-forming molecular clouds\, and scales of galactic disks\, s
 how star formation efficiencies and rates that are consistent with detaile
 d observations in the nearby universe\, and also indicate strong sensitivi
 ty to environment.  At high densities and where dust and metal abundances 
 are high\, stellar radiation does not propagate as far\, and cooling rates
  are enhanced.  As a result of the reduced effectiveness of feedback in ma
 intaining the ISM pressure (turbulent\, thermal\, and magnetic)\, star for
 mation rates and efficiencies are expected to increase in high-density env
 ironments.  Results from suites of resolved star-forming ISM simulations h
 ave been used to calibrate new subgrid models\, and incorporation of these
  new results in galaxy formation models may potentially significantly chan
 ge predictions for star formation at high redshift.   
LOCATION:Hoyle Lecture Theatre\, Institute of Astronomy (and online - deta
 ils to be sent by e-mail)
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