Non-universality of dark-matter halos: Cusps, cores, and the central potential
- Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen Ø (Denmark)
- School of Physics and Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States)
Dark-matter halos grown in cosmological simulations appear to have central Navarro–Frenk–White-like density cusps with mean values of dlogρ/dlogr≈−1, and some dispersion, which is generally parametrized by the varying index α in the Einasto density profile fitting function. Non-universality in profile shapes is also seen in observed galaxy clusters and possibly dwarf galaxies. Here we show that non-universality, at any given mass scale, is an intrinsic property of DARKexp, a theoretically derived model for collisionless self-gravitating systems. We demonstrate that DARKexp—which has only one shape parameter, ϕ{sub 0}—fits the dispersion in profile shapes of massive simulated halos as well as observed clusters very well. DARKexp also allows for cored dark-matter profiles, such as those found for dwarf spheroidal galaxies. We provide approximate analytical relations between DARKexp ϕ{sub 0}, Einasto α, or the central logarithmic slope in the Dehnen–Tremaine analytical γ-models. The range in halo parameters reflects a substantial variation in the binding energies per unit mass of dark-matter halos.
- OSTI ID:
- 22882637
- Journal Information:
- Astrophysical Journal, Vol. 811, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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