The Cosmogrid Simulation: Statistical Properties of Small Dark Matter Halos

Abstract

We present the results of the “Cosmogrid” cosmological N -body simulation suites based on the concordance LCDM model. The Cosmogrid simulation was performed in a 30Mpc box with 20483 particles. The mass of each particle is 1.28× 10M!, which is sufficient to resolve ultra-faint dwarfs. We found that the halo mass function shows good agreement with the Sheth & Tormen (1999) fitting function down to ∼ 10M!. We have analyzed the spherically averaged density profiles of the three most massive halos which are of galaxy group size and contain at least 170 million particles. The slopes of these density profiles become shallower than −1 at the inner most radius. We also find a clear correlation of halo concentration with mass. The mass dependence of the concentration parameter cannot be expressed by a single power law, however a simple model based on the Press-Schechter theory gives reasonable agreement with this dependence. The spin parameter does not show a correlation with the halo mass. The probability distribution functions for both concentration and spin are well fitted by the log-normal distribution for halos with the masses larger than ∼ 10M!. Subject headings: cosmology: theory —galaxies: dwarf —methods: numerical —dark matter

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Cite this paper

@inproceedings{Ishiyama2011TheCS, title={The Cosmogrid Simulation: Statistical Properties of Small Dark Matter Halos}, author={Tomoaki Ishiyama and Junichiro Makino and Keigo Nitadori and Steven Rieder and Cees T. A. M. de Laat and Stephen McMillan and Kei Hiraki and Stefan Harfst}, year={2011} }