Does Dark Matter at the Center and in the Halo of the Galaxy Consist of the Same Particles?

Abstract

After a discussion of the properties od degenerate fermion balls, we analize the orbits of the star S0-1, which has the smallest projected distance to Sgr A*, in the supermassive black hole as well as in the fermion ball scenarios of the Galactic center. It is shown that both scenarios are consistent with the data,as measured during the last six yiers by Genzel ae al. and Ghez et al.. We then consider a self-gravitating ideal fermion gas at nonzero temperature as a model for the Galactic halo. The Galactic halo of mass ~2 x 10^12 Msol enclosed within a radius of ~200 kpc implies the existence of a supermassive compact dark object at the Galactic center that is in hydrostatic and thermal equilibrium with the halo. The central object has a maximal mass of ~2.3 x 10^6 Msol within a minimal radius of ~18 mpc for fermion masses ~15 keV. We thus conclude that both the supermassive compact dark object and the halo could be made of the same weakly interacting ~15 keV particle.