Triaxial Modeling of Halo Density Profiles with High - resolution N - body Simulations

We present a detailed non-spherical modeling of dark matter halos on the basis of a combined analysis of the high-resolution halo simulations (12 halos with N ∼ 10 particles within their virial radius) and the large cosmological simulations (5 realizations with N = 512 particles in a 100hMpc boxsize). The density profiles are well approximated by a sequence of the concentric triaxial distribution with their axis directions being fairly aligned. We characterize the triaxial model quantitatively by generalizing the universal density profile which has previously been discussed only in the framework of the spherical model. We obtain a series of practically useful fitting formulae in applying the triaxial model; the mass and redshift dependence of the axis ratio, the mean the concentration parameter, and the probability distribution functions of the the axis ratio and the concentration parameter. These accurate fitting formulae form a complete description of the triaxial density profiles of halos in Cold Dark Matter models. Our current description of the dark halos will be particularly useful in predicting a variety of nonsphericity effects, to a reasonably reliable manner, including the gas and temperature profiles of X-ray clusters, the estimates of the Hubble constant estimated via the Sunyaev – Zel’dovich effect, the weak and strong lens statistics, and the non-linear clustering of dark matter. Subject headings: galaxies: clusters: general – cosmology: miscellaneous – methods: numerical