The Dark Matter Profiles in the Milky Way

Abstract

We investigate the dark matter profile of the Milky Way using the observed rotation curve data out to 100 kpc. The baryonic matter of the Milky Way is divided into bulge, disk and gas components, and each component is modelled using various possible mass profiles available in literature. The arbitrary combination of seven bulge profiles, four disk profiles and two gas profiles results in fifty-six baryon models. These baryon models are combined with one of the four dark matter profiles: Burkert profile, core-modified profile, pseudo-isothermal profile and NFW profile, to fit the observed rotation curve data. Results show that in general the NFW profile fits the data better than the Burkert profile, while the core-modified profile and the pseudo-isothermal profile are essentially ruled out. The best-fitting NFW model has the scale length $r_0=8.1\pm 0.7$ kpc, and the corresponding local density of dark matter is $\rho_{\rm dm}(R=R_\odot)=0.51\pm0.09~{\rm GeV}/{\rm cm}^3$.