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Galaxy halo formation in the absence of violent relaxation and a universal density profile of the halo center

  • While N-body simulations testify to a cuspy profile of the central region of dark matter halos, observations favor a shallow, cored density profile of the central region of at least some spiral galaxies and dwarf spheroidals. We show that a central profile, very close to the observed one, inevitably forms in the center of dark matter halos if we make a supposition about a moderate energy relaxation of the system during the halo formation. If we assume the energy exchange between dark matter particles during the halo collapse is not too intensive, the profile is universal: it depends almost not at all on the properties of the initial perturbation and is very akin, but not identical, to the Einasto profile with a small Einasto index n similar to 0.5. We estimate the size of the "central core" of the distribution, i.e., the extent of the very central region with a respectively gentle profile, and show that the cusp formation is unlikely, even if the dark matter is cold. The obtained profile is in good agreement with observational dataWhile N-body simulations testify to a cuspy profile of the central region of dark matter halos, observations favor a shallow, cored density profile of the central region of at least some spiral galaxies and dwarf spheroidals. We show that a central profile, very close to the observed one, inevitably forms in the center of dark matter halos if we make a supposition about a moderate energy relaxation of the system during the halo formation. If we assume the energy exchange between dark matter particles during the halo collapse is not too intensive, the profile is universal: it depends almost not at all on the properties of the initial perturbation and is very akin, but not identical, to the Einasto profile with a small Einasto index n similar to 0.5. We estimate the size of the "central core" of the distribution, i.e., the extent of the very central region with a respectively gentle profile, and show that the cusp formation is unlikely, even if the dark matter is cold. The obtained profile is in good agreement with observational data for at least some types of galaxies but clearly disagrees with N-body simulations.zeige mehrzeige weniger

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Metadaten
Verfasserangaben:Anton N. Baushev
DOI:https://doi.org/10.1088/0004-637X/786/1/65
ISSN:0004-637X
ISSN:1538-4357
Titel des übergeordneten Werks (Englisch):The astrophysical journal : an international review of spectroscopy and astronomical physics
Verlag:IOP Publ. Ltd.
Verlagsort:Bristol
Publikationstyp:Wissenschaftlicher Artikel
Sprache:Englisch
Jahr der Erstveröffentlichung:2014
Erscheinungsjahr:2014
Datum der Freischaltung:27.03.2017
Freies Schlagwort / Tag:astroparticle physics; dark matter; elementary particles; large-scale structure of universe
Band:786
Ausgabe:1
Seitenanzahl:8
Fördernde Institution:Bundesministerium fur Bildung und Forschung through DESY-PT [05A11IPA]; Helmholtz Alliance for Astroparticle Physics (HAP) - Initiative and Networking Fund of the Helmholtz Association
Organisationseinheiten:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie
Peer Review:Referiert
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