Evolution of density perturbations in a universe dominated by multiple dark matter

Abstract

We consider a flat universe dominated by a mixture of hot and cold dark matter. The cold dark matter is treated by the fluid approximation, as are the radiation and baryons, while the hot dark matter (massive neutrinos) is treated as a collisionless gas with the Fermi-Dirac distribution. We compare our calculated results with the observations on the anisotropy of the cosmic radiation background, the large-scale peculiar motion of galaxies and the galaxy luminosity function, and discuss the constraints imposed by these observations on the model parameters, particularly the fraction of hot dark matter and the Hubble constant