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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-1045
DTSTART:20080228T213000Z
DURATION:PT1H0M0S
DTSTAMP:20260423T055122Z
LAST-MODIFIED:19700101T060000Z
LOCATION:Room TBA
SUMMARY:Dark Matter in Dwarf Galaxies\, Astronomy Colloquium\, Josh Si
 mon\, CALTECH
DESCRIPTION:Over the last several years\, three crucial shortcomings o
 f the Cold Dark Matter (CDM) model have been discovered on galaxy-size
  scales. I present new observations addressing two of these problems: 
 the missing satellite problem and the central density problem. I descr
 ibe results from a Keck spectroscopic survey of the ultra-faint dwarf 
 galaxies orbiting the Milky Way that were recently discovered by the S
 loan Digital Sky Survey. We measure the masses of these galaxies based
  on their stellar kinematics and investigate whether they can account 
 for the missing CDM satellites. I also present a rotation curve analys
 is of eight nearby low mass disk galaxies\, based on high-resolution 2
 D velocity fields in Halpha and CO. This observing program has been de
 signed to overcome some of the limitations of other rotation curve stu
 dies that rely mostly on long-slit spectra or low-resolution HI observ
 ations. We find that these objects exhibit the full range of dark matt
 er density profiles between constant density and NFW halos\, in contra
 st to the single universal density profile seen in CDM simulations. We
  consider possible explanations for the differences between observed a
 nd expected density profiles and argue that they are consistent with b
 eing caused by halo triaxiality.
URL:https://www.physics.wisc.edu/events/?id=1045
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