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SUMMARY:The fine-scale structure of dark matter halos - Simon White (Max P
 lanck)
DTSTART:20120307T141500Z
DTEND:20120307T151500Z
UID:TALK36259@talks.cam.ac.uk
CONTACT:Pau Figueras
DESCRIPTION:A wide range of astronomical observations indicate that cosmic
 \nstructure formation is driven by the gravitational effects of dark\nmatt
 er. This contributes about 80 percent of the total cosmic mass\nbudget and
  interacts extremely weakly with light and with all known\nforms of matter
 . It is most plausibly a new kind of elementary\nparticle\, yet to be dete
 cted directly or indirectly on Earth. At the\ntime of recombination\, 400\
 ,000 years after the Big Bang\, the Universe was almost uniform\, its only
  structure being weak linear fluctuations with statistical properties that
  can be inferred directly from observations of the cosmic microwave backgr
 ound. At this time dark matter particles had small thermal velocities and 
 their distribution deviated from uniformity only through a gaussian field 
 of density fluctuations with associated motions. Later evolution was drive
 n purely by gravity and so obeyed the collisionless Boltzmann equation. Th
 is has immediate consequences for the present distribution of dark matter\
 , even in extremely nonlinear regions such as the part of the Galaxy where
  the Sun resides. I will show how this structure can be followed in full g
 enerality in high-resolution N-body simulations by integrating the Geodesi
 c Deviation Equation in tandem with the equations of motion\, enhancing th
 e effective resolution by more than 10 orders of magnitude and permitting 
 a detailed treatment of annihilation radiation from dark matter caustics. 
 I will also discuss how the predicted distribution at the Sun's position i
 mpacts the expectations for terrestrial experiments seeking to detect the 
 dark matter directly\, in particular\, the possibility of extremely narrow
  line signals that may be visible in axion detectors.
LOCATION:MR2\, Centre for Mathematical Sciences
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