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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-2791
DTSTART:20120920T203000Z
DTEND:20120920T220000Z
DTSTAMP:20260420T022206Z
LAST-MODIFIED:20120912T145158Z
LOCATION:4421 Sterling Hall
SUMMARY:Turbulence and Cosmic-Rays in Galaxy Clusters\, Astronomy Coll
 oquium\, Peng Oh\, UC Santa Barbara
DESCRIPTION:Although the non-thermal component of the ICM has a relati
 vely low energy density\, it can still exert a profound influence. Tur
 bulence provides pressure support\, affects magnetic field topology an
 d thus thermal conduction\, and is a source of dissipation\, heat and 
 metal diffusion. Cosmic-rays likewise provide pressure support and hea
 ting\, and contain archaeological information about cosmological shock
 s and AGN activity\, which can be mined in radio and gamma-ray data. W
 e discuss several aspects. Turbulence: we develop a novel spectral ana
 lysis technique for Astro-H which exploits not just the line width but
  the entire line shape\, and show how the excellent spectral resolutio
 n of Astro-H can overcome its relatively poor spatial resolution in ma
 king detailed inferences about the ICM velocity field. Cosmic rays: we
  show how super-Alfvenic streaming of cosmic rays can turn off radio h
 alos\, potentially explaining the observed bimodality in radio halo lu
 minosity. We also show how diffusive shock acceleration in previous st
 ructure formation shocks can leave behind a fossil a^1/4 MeV electron 
 population in the cluster outskirts\, in the face of loss processes. R
 elic reacceleration can dominate over fresh injection at low Mach numb
 ers\, allowing weak shocks which would would be otherwise invisible to
  glow in radio emission\, potentially visible with LOFAR.
URL:https://www.physics.wisc.edu/events/?id=2791
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