Empirical models for Dark Matter Halos
Abstract
(Abridged) We use techniques from nonparametric function estimation theory to extract the density profiles, and their derivatives, from a set of N-body halos, and compare these with a variety of parametric models. We consider halos generated from isolated spherical collapses and LCDM simulations of gravitational clustering. The models include an NFW-like model with arbitrary inner power-law slope gamma, Sersic's r^{1/n} model (traditionally applied to projected light-profiles), and the density model of Prugniel & Simien (PS) that was designed to match the deprojected form of the Sersic model and is applied here for the first time to dark matter halos. The Sersic and PS models perform the best, with an rms scatter four times smaller than that obtained with the NFW-like model in the case of the cold collapses. The location of the (10^{12} M_sun) galaxy-sized, N-body halos in the _e-log(R_e) and log(rho_e)-log(R_e) diagrams coincides with that of brightest cluster galaxies, consistent with the new relation log(rho_e) = 1.15 - 2.5log(R_e) defined by luminous elliptical galaxies. We provide analytical expressions for the slopes of the empirical models, and compare these with data from real galaxies. Depending on the Sersic parameters of the dark matter halo, one can expect an extrapolated, inner (0.01 - 1 kpc), logarithmic profile slope ranging from -0.2 to -1.5, with a typical value at 0.1 kpc around -0.7. We also present the radial behavior of rho(r)/sigma(r)^3 for the Sersic and PS models, finding they are well approximated by a power-law with slope slightly shallower than -2 near r=r_{-2}.Keywords
All Related Versions
This publication has 0 references indexed in Scilit: