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

TL;DR

This paper derives a new cosmological model incorporating fluctuation energy from second-order perturbations, showing it can reconcile the Hubble constant with observations by treating fluctuation energy as dark matter.

Contribution

It introduces a novel approach to include fluctuation energy from second-order perturbations into cosmological models, addressing the Hubble-constant problem.

Findings

Models with fluctuation energy match recent observational Hubble values.

Fluctuation energy acts as a form of dark matter in the models.

Perturbation analysis of densities supports model consistency.

Abstract

First the fluctuation energy is derived from the adiabatic random fluctuations due to the second-order perturbation theory, and the evolutionary relation for it is expressed in the form of rho_f = rho_f (rho), where rho and rho_f 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 rho and rho_f are studied.