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SUMMARY:Evolution of dark matter velocity dispersion
DTSTART:20190322T130000Z
DTEND:20190322T150000Z
DTSTAMP:20260425T010300Z
UID:indico-event-790489@indico.cern.ch
DESCRIPTION:Speakers: Stefan Floerchinger (Institut für Theoretische Phys
 ik\, Ruprecht-Karls-Universität Heidelberg)\n\nCosmological perturbation 
 theory for the late Universe dominated by dark matter is extended beyond t
 he perfect fluid approximation by taking the dark matter velocity dispersi
 on tensor as an additional field into account. A proper tensor decompositi
 on of the latter leads to two additional scalar fields\, as well as a vect
 or and a tensor field. Most importantly\, the trace of the velocity disper
 sion tensor can have a spatially homogeneous and isotropic expectation val
 ue. While it decays at early times\, we show that a back-reaction effect q
 uadratic in perturbations makes it grow strongly at late times. We compare
  sterile neutrinos as a candidate for comparatively warm dark matter to we
 akly interacting massive particles as a rather cold dark matter candidate 
 and show that the late time growth of velocity dispersion is stronger for 
 the latter. Another feature of a non-vanishing velocity dispersion expecta
 tion value is that it destroys the apparent self-consistency of the single
 -stream approximation and allows thereby to treat times and scales beyond 
 shell-crossing.\n\nhttps://indico.cern.ch/event/790489/
LOCATION:4/2-037 - TH meeting room (CERN)
URL:https://indico.cern.ch/event/790489/
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