Growth of black holes and dark matter accretion

We investigate the distribution of fermion dark matter in the Milky Way galaxy and find that dark matter could gravitationally condensate in a degenerate core of mass of 3 × 10 6 M embedded in a dark matter halo of 3 × 10 12 M with a size of about 200 kpc. We then show that the galactic black hole of mass of about 3 × 10 6 M might have grown from a stellar seed black hole by mainly accreting dark matter from the compact degenerate fermion core. This leads to a lower limit on the mass of the fermion dark matter of about (6–10) keV. It is then argued that the constrained dark matter could be a sterile neutrino.