Journal Article

Phase-space density profiles in scale-free cosmologies

Steffen R. Knollmann, Alexander Knebe and Yehuda Hoffman

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 391, issue 2, pages 559-564
Published in print December 2008 | ISSN: 0035-8711
Published online November 2008 | e-ISSN: 1365-2966 | DOI:
Phase-space density profiles in scale-free cosmologies

Show Summary Details


We use a set of high-resolution simulations of scale-free Einstein-de Sitter cosmologies to investigate the logarithmic slope of the phase-space density profile Q(r) =ρ(r)/σ3(r) of dark matter (DM) haloes. The initial conditions for the simulations are determined by a power-law power spectrum of the form P(k) ∝kn. We compute the Q(r) profiles using the radial, tangential and full velocity dispersion, and the velocity anisotropy parameter, β(r). We express Q(r) as a single power-law Q(r) ∝rα and derive a median slope α in each simulation and for each definition of Q. Our main findings are: (i) the various Q(r) profiles follow a power law to a good approximation. (ii) The slopes depend on the concentration parameter c of the DM haloes, where for c≳ 10 the slopes steepen with rising concentration and for c≲ 10 the trend flattens and even turns around. (iii) The asymptotic value of β as rRvir increases with the value of c. (iv) In accordance with Zait, Hoffman & Shlosman, αrad becomes more negative as the asymptotic value of β at the virial radius increases. (iv) This introduces a weak dependence of the Q(r) slopes on the slope of the power spectrum.

Keywords: methods: numerical; cosmology: theory; dark matter

Journal Article.  4075 words.  Illustrated.

Subjects: Astronomy and Astrophysics

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.