2004/03/15 by Renyue Cen, Cen, Renyue, Feng Dong +5
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0403352
38 pages, submitted to ApJ, name revised (the first author name was wrong)
arxiv created 2004/03/16 · arxiv updated 2009/12/01
We compute the properties of dark matter halos with mass 106.5-109\msun at redshift z=6-11 in the standard cold dark matter cosmological model, utilizing a very high resolution N-body simulation. We find that dark matter halos in these mass and redshift ranges are significantly biased over matter with a bias factor in the range 2-6. The dark matter halo mass function displays a slope of 2.05± 0.15 at the small mass end. We do not find a universal dark matter density profile. Instead, we find a significant dependence of the central density profile of dark matter halos on halo mass and epoch with α0=0.4-1.0; the high-mass (M≥ 108\msun) low-redshift (z∼ 6) halos occupy the high end of the range and low-mass (M∼ 107\msun) high-redshift (z∼ 11) halos occupy the low end. Additionally, for fixed mass and epoch there is a significant dispersion in α0 due to the stochastic assembly of halos. Our results fit a relationship of the form α0=0.75((1+z)/7.0)-1.25(M/107\msun)0.11(1+z)/7.0 with a dispersion about this fit of ± 0.5 and no systematic dependence of variance correlated with environment. The median spin parameter of dark matter halos is 0.03-0.04 but with a large lognormal dispersion of ∼ 0.4. Various quantities are tabulated or fitted with empirical formulae.