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The inner structure of ΛCDM haloes - III. Universality and asymptotic slopes

Navarro, J. F. ; Hayashi, E. ; Power, C. ; Jenkins, A. R. ; Frenk, C. S. ; White, S. D. M. ; Springel, V. ; Stadel, J. ; Quinn, T. R.

In: Monthly Notices of the Royal Astronomical Society, 2004, vol. 349, no. 3, p. 1039-1051

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    Titel
    • The inner structure of ΛCDM haloes - III. Universality and asymptotic slopes
    Autor
    • Navarro, J. F.. Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8P 1A1, Canada
    • Hayashi, E.. Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8P 1A1, Canada
    • Power, C.. Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE
    • Jenkins, A. R.. Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE
    • Frenk, C. S.. Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE
    • White, S. D. M.. Max-Planck Institute for Astrophysics, Garching, Munich, D-85740, Germany
    • Springel, V.. Max-Planck Institute for Astrophysics, Garching, Munich, D-85740, Germany
    • Stadel, J.. Institute for Theoretical Physics, University of Zurich, Zurich CH-8057, Switzerland
    • Quinn, T. R.. Department of Astronomy, University of Washington, Seattle, WA 98195, USA
    Dokumententyp
    • Postprint
    Sprache
    • Englisch
    Veröffentlicht in
    • Monthly Notices of the Royal Astronomical Society, 2004, vol. 349, no. 3, p. 1039-1051. Blackwell Science Ltd
    Andere elektronische Ausgabe
    OAI-PMH-ID
    • oai:doc.rero.ch:291358
    Summary
    We investigate the mass profile of cold dark matter (ΛCDM) haloes using a suite of numerical simulations spanning five decades in halo mass, from dwarf galaxies to rich galaxy clusters. These haloes typically have a few million particles within the virial radius (r200), allowing robust mass profile estimates down to radii <1 per cent of r200. Our analysis confirms the proposal of Navarro, Frenk & White (NFW) that the shape of the ΛCDM halo mass profiles differs strongly from a power law and depends little on mass. The logarithmic slope of the spherically averaged density profile, as measured by β=−d ln ρ/d ln r, decreases monotonically towards the centre and becomes shallower than isothermal (β < 2) inside a characteristic radius, r−2. The fitting formula proposed by NFW provides a reasonably good approximation to the density and circular velocity profiles of individual haloes; circular velocities typically deviate from NFW best fits by <10 per cent over the radial range that is numerically well resolved. Alternatively, systematic deviations from the NFW best fits are also noticeable. Inside r−2, the profile of simulated haloes becomes shallower with radius more gradually than predicted and, as a result, NFW fits tend to underestimate the dark matter density in these regions. This discrepancy has been interpreted as indicating a steeply divergent cusp with asymptotic inner slope, β0≡β(r = 0) ∼ 1.5. Our results suggest a different interpretation. We use the density and enclosed mass at our innermost resolved radii to place strong constraints on β0: density cusps as steep as r−1.5 are inconsistent with most of our simulations, although β0= 1 is still consistent with our data. Our density profiles show no sign of converging to a well-defined asymptotic inner power law. We propose a simple formula that reproduces the radial dependence of the slope better than the NFW profile, and so may minimize errors when extrapolating our results inward to radii not yet reliably probed by numerical simulations