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CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-1216
DTSTART:20080821T210000Z
DURATION:PT1H0M0S
DTSTAMP:20260423T010315Z
LAST-MODIFIED:20080819T173331Z
LOCATION:4274 Chamberlin
SUMMARY:The quest for missing baryons through X-ray spectroscopy\, NPA
 C (Nuclear/Particle/Astro/Cosmo) Forum\, Yoh Takei\, ISAS in Tokyo
DESCRIPTION:Recent cosmic microwave background observations determined
  that 96 percent of the Universe is "dark" (dark energy and dark matte
 r). Baryons account for only 4 percent of the Universe. However about 
 a half of the baryons still remain to be observed. These are the "miss
 ing baryons". Since baryons are rather familiar and even exciting -- s
 tars\, galaxies\, planets and creatures are all baryons -- it is a sha
 me that we don't understand a large part of them. Simulations of the c
 osmic large scale structure formation predict that the missing baryons
  exist as intergalactic gas with a temperature of about one million K\
 , the so-called warm-hot intergalactic medium (WHIM). If the WHIM exis
 ts\, the highly ionized metals (O\, Ne\, etc) in the WHIM produce emis
 sion and/or absorption lines in the X-ray energy range. The limited se
 nsitivity of the detectors\, however\, makes WHIM still undetected. We
  have been searching cluster vicinities for the evidence of the WHIM\,
  where the existence of relatively denser and hotter WHIM is expected\
 , through X-ray spectroscopy (more particularly\, O and Ne emission/ab
 sorption features). Despite some early positive reports\, evidence for
  the WHIM has not yet been obtained. But the upper limits of the signa
 ls we have from recent observations indicate that our sensitivity is r
 eaching the expected signal level. I present the details of our study\
 , mainly those from Suzaku (Japanese X-ray satellite)\, and then show 
 the future prospects of this field.
URL:https://www.physics.wisc.edu/events/?id=1216
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