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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-3669
DTSTART:20150305T213000Z
DTEND:20150305T230000Z
DTSTAMP:20260414T124404Z
LAST-MODIFIED:20150224T133442Z
LOCATION:4421 Sterling Hall
SUMMARY:News from the Extreme Energy Cliff\, Astronomy Colloquium\, Pr
 ofessor Angela Olinto\, University of Chicago
DESCRIPTION: Thanks to giant extensive air-showers observatories\, suc
 h as the Pierre Auger Observatory and the Telescope Array (TA)\, we no
 w know that the sources of ultrahigh energy cosmic rays (UHECRs) are e
 xtragalactic. We also know that either they interact with the CMB as p
 redicted or they run out of energy at the same energy scale of the CMB
  interactions! Their composition is either surprising (dominated by he
 avier nuclei at the highest energies) or the hadronic interactions at 
 100 TeV are not a standard extrapolation of LHC interaction energies. 
 Hints of anisotropies begin to appear as energies reach 60 EeV\, just 
 when statistics become very limited.<br>
\n            Basic questions
  remain unanswered: What generates such extremely energetic particles 
 that reach above 10^20 eV (100 EeV)? Where do they come from? How do t
 hey reach these energies? What are they? How do they interact on their
  way to Earth and with the Earth’s atmosphere?<br>
\n            A h
 otspot seen by TA may be the first hint of a source. Neutrino and gamm
 a-ray follow ups may clarify this tantalizing possibility. In addition
 \, a large increase in statistics of UHECRs is needed. Space missions 
 are now being studied to increase the exposure to UHECR such as the JE
 M-EUSO mission: the Extreme Universe Space Observatory (EUSO) at the J
 apanese Experiment Module (JEM).<br>
\n
URL:https://www.physics.wisc.edu/events/?id=3669
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