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PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-3658
DTSTART:20150226T213000Z
DTEND:20150226T230000Z
DTSTAMP:20260315T115327Z
LAST-MODIFIED:20150212T132250Z
LOCATION:4421 Sterling Hall
SUMMARY:Cosmic ray feedback in Galaxies and Cool Core Clusters\, Astro
 nomy Colloquium\, CHristopher Pfrommer\, HITS Heidelberg
DESCRIPTION:Understanding the physics of galaxy formation is arguably 
 among the greatest problems in modern astrophysics. Recent cosmologica
 l simulations have demonstrated that "feedback" by star formation\, su
 pernovae and active galactic nuclei appears to be critical in obtainin
 g realistic disk galaxies\, to slow down star formation to the small o
 bserved rates\, to move gas and metals out of galaxies into the interg
 alactic medium\, and to balance radiative cooling of the low-entropy g
 as at the centers of galaxy clusters. However the particular physical 
 processes underlying this "feedback" still remain elusive. In particul
 ar\, these simulations neglected cosmic rays and magnetic fields\, whi
 ch provide a comparable pressure support in comparison to turbulence i
 n our Galaxy\, and are known to couple dynamically and thermally to th
 e gas. Using hydrodynamic simulations of galaxy formation\, I will sho
 w how cosmic rays are able to drive powerful galactic winds in low-mas
 s galaxies. This reduces the available amount of gas for star formatio
 n and implies a shallower slope of the faint-end of the galaxy luminos
 ity function as required by observations. In the second part of the ta
 lk I demonstrate that cosmic-ray heating can balance radiative cooling
  of the low-entropy gas at the centers of galaxy clusters and helps in
  mitigating the star formation of the brightest cluster galaxies. New 
 data on the low-frequency radio and gamma-ray emission of M87\, the cl
 osest active galaxy interacting with the cooling cluster plasma\, enab
 le us to put forward a comprehensive\, physics-based model of feedback
  by active galactic nuclei. 
URL:https://www.physics.wisc.edu/events/?id=3658
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