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SUMMARY:Evolution of dark matter velocity dispersion
DTSTART;VALUE=DATE-TIME:20190322T130000Z
DTEND;VALUE=DATE-TIME:20190322T150000Z
DTSTAMP;VALUE=DATE-TIME:20190320T121715Z
UID:indico-event-790489@indico.cern.ch
DESCRIPTION:Cosmological perturbation theory for the late Universe dominat
 ed by dark matter is extended beyond the perfect fluid approximation by ta
 king the dark matter velocity dispersion tensor as an additional field int
 o account. A proper tensor decomposition of the latter leads to two additi
 onal scalar fields\, as well as a vector and a tensor field. Most importan
 tly\, the trace of the velocity dispersion tensor can have a spatially hom
 ogeneous and isotropic expectation value. While it decays at early times\,
  we show that a back-reaction effect quadratic in perturbations makes it g
 row strongly at late times. We compare sterile neutrinos as a candidate fo
 r comparatively warm dark matter to weakly interacting massive particles a
 s a rather cold dark matter candidate and show that the late time growth o
 f velocity dispersion is stronger for the latter. Another feature of a non
 -vanishing velocity dispersion expectation value is that it destroys the a
 pparent self-consistency of the single-stream approximation and allows the
 reby to treat times and scales beyond shell-crossing.\n\nhttps://indico.ce
 rn.ch/event/790489/
LOCATION:CERN 4-2-037 - TH meeting room
URL:https://indico.cern.ch/event/790489/
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