The differential energy distribution of the universal density profile of dark halo

Abstract

We study the differential energy distribution of dark matter halos, carrying out cosmological N-body simulation.We give an analytical formula of the differential energy distribution of dark matter in the halos obtained by the numerical simulation.From the analytical formula we reconstruct the density profile described by the Navarro,Frenk, & White (NFW) profile.The NFW profile is consistent with the analytical formula of our fractional mass distribution. We find that a parameter in our analytical formula of differential energy distribution which is related with the slope of inner cusp of dark halo.We obtain the distribution function for the NFW profile which has sharp cut off at the high binding energy.We discuss physical reason of form of the analytical formula.