Cosmological models with the energy density of random fluctuations and the Hubble-constant problem

Abstract

The fluctuation energy is derived from adiabatic random fluctuations due to second-order perturbation theory, and the evolutionary relation for it is expressed in the form of ρf = ρf (ρ), where ρ and ρf are the densities of ordinary dust and the fluctuation energy, respectively. The pressureless matter as a constituent of the universe at the later stage is assumed to consist of ordinary dust and the fluctuation energy. Next, cosmological models including the fluctuation energy as a kind of dark matter are derived using the above relation, and it is found that the Hubble parameter and the other model parameters in the derived models can be consistent with the recent observational values. Moreover, the perturbations of ρ and ρf are studied.