Toward a Theory of the Evolution of Perturbations of the Dark Matter Density in the Very Early Universe

Abstract

We investigate the influence of primordial baryonic matter in the form of cosmic plasma on the evolution of perturbations in dark matter considered as a gas of weakly interacting massive particles (WIMPs). Nonstationary equations of state of the WIMP gas for both its ideal model and its real model are proposed along with the state parameter of the gas in the form of a power-law dependence on time. A description of the appearance in the WIMP gas of seed perturbations is given which takes account of the influence of the primordial cosmic plasma and the variability of the state parameter of dark matter. Regimes of the evolution of perturbations of non-baryonic matter are found, describing their growth for various characteristics of the internal energy of the WIMP gas. The size and mass of the seed perturbations in the WIMP gas are estimated.