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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:3
UID:UW-Physics-Event-7932
DTSTART:20221129T220000Z
DTEND:20221129T230000Z
DTSTAMP:20260414T071353Z
LAST-MODIFIED:20221128T141258Z
LOCATION:Chamberlin 5280
SUMMARY:Dark Matter Substructure: simulations\, semi-analytic models a
 nd observations\, Theory Seminar (High Energy/Cosmology)\, Xiaolong Du
 \, Carnegie Observatories & UCLA
DESCRIPTION:Roughly 85% of the matter in the Universe is in the form o
 f invisible matter\, i.e. dark matter. Under gravitational interaction
 s\, dark matter clusters and forms hierarchical structure. Over the la
 st decades\, simulations with higher and higher resolutions have great
 ly improved our understanding of the formation of dark matter halos an
 d the properties of their substructure (subhalo). Simulations of the s
 tandard cold dark matter (CDM) show that CDM halos have cuspy density 
 profiles and contain a large number of small subhalos\, which are not 
 fully consistent with the current observations of dwarf galaxies. Thus
  different dark matter models\, such as warm dark matter\, self-intera
 cting dark matter\, fuzzy dark matter\, have been proposed\, which pre
 dict very different phenomena on small scales (~kpc). Running numerica
 l simulations under different dark matter assumptions requires a large
  amount of computing resource. On the hand\, even the state-of-art sim
 ulations suffer from numerical artifacts\, limiting their predicting p
 ower on small scales. In this talk\, I will talk about some of our lat
 est progresses in modeling the evolution of subhalos using the semi-an
 alytic code Galacticus and how we can model and control the numerical 
 artifacts. Using our semi-analytic models\, we can get accurate predic
 tions for the abundance of subhalos and the evolution of their density
  profiles due to tidal effects. Our semi-analytic models are ~10^4 tim
 es faster than direct simulations\, making it possible to generate a l
 arge number of realizations of dark matter halo systems with correct s
 ubstructure\, which are useful for getting robust constraint on differ
 ent dark matter models from observations such as strong gravitational 
 lensing.
URL:https://www.physics.wisc.edu/events/?id=7932
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