2003/11/04 by M. Hoeft, J. P. Mücket, J. P. Muecket +2 · 2 citations
Physics and Astronomy · #Dark Matter and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #Scientific Research and Discoveries #astro-ph
paper · pdf · doi:10.1086/380990
published as Astrophys.J. 602 (2004) 162-169 · 9 pages, 5 figures bw, accepted for publication in ApJ
arxiv created 2003/11/04 · openalex publication_date 2004/02/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
Numerous numerical studies indicate that dark matter halos show an almost universal radial density profile. The origin of the profile is still under debate. We investigate this topic and pay particular attention to the velocity dispersion profile. To this end, we have performed high-resolution simulations with two independent codes, ART and GADGET. The radial velocity dispersion can be approximated as a function of the potential by σ = a (Φ/Φ out ) κ (Φ out - Φ), where Φ out is the outer potential of the halo. For the parameters a and κ, we find that a = 0.29 ± 0.04 and κ = 0.41 ± 0.03. We find that the power-law asymptote, σ 2 ∝ Φ κ , is valid out to much larger distances from the halo center than any power-law asymptote for the density profile ρ ∝ r - n . The asymptotic slope n ( r → 0) of the density profile is related to the exponent κ via n = 2κ/(1 + κ). Thus, the value obtained for κ from the available simulation data can be used to obtain an estimate of the density profile below currently resolved scales. We predict a continuously decreasing n toward the halo center with the asymptotic value n ≲ 0.58 at r = 0.