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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-2341
DTSTART:20120126T203000Z
DURATION:PT1H0M0S
DTSTAMP:20260420T062159Z
LAST-MODIFIED:20120121T003519Z
LOCATION:4274 Chamberlin Hall
SUMMARY:Measuring the Extragalactic Magnetic Field Via Gamma-Ray Blaza
 r Observations\, NPAC (Nuclear/Particle/Astro/Cosmo) Forum\, Tom Weisg
 arber\, University of Chicago
DESCRIPTION:Despite many efforts\, the extragalactic magnetic field (E
 GMF)\, presumed to exist in the voids of the large scale structure\, r
 emains undetected. Since the EGMF may be generated either by processes
  in the early universe or by outflows from galaxies\, and it could sup
 ply the seed fields required by many models of galactic and cluster fi
 eld formation\, its properties are of interest from both cosmological 
 and astrophysical viewpoints. I will review a recently developed techn
 ique for measuring the EGMF strength using combined gamma-ray observat
 ions from the Fermi Gamma-Ray Space Telescope and ground-based instrum
 ents such as VERITAS. The technique relies on modeling the electromagn
 etic cascade that develops in extragalactic space due to gamma-ray int
 eractions with the extragalactic background light and CMB and for the 
 first time permits the placement of a lower limit on the EGMF strength
 . I will describe two approaches to characterizing the cascade and dis
 cuss the interpretation of gamma-ray observations of the blazar RGB J0
 710+591 as limits on the existence of an EGMF-induced "halo."
URL:https://www.physics.wisc.edu/events/?id=2341
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