The dominating stage of cosmological vacuum

Abstract

1. At the present time, the cosmological medium is a set of the following components: dark energy (DE), dark matter (DM), baryon substance, and radiation. According to the experimental data discussed in [1], the density of DE is 74%, those of DM, baryon substance, and radiation – 22%, 4%, and – 0.01% of the total density, respectively. Despite the smallness of the latter, radiation will be taken into account in our studies. Dark energy consists of supesymmetric massless particles referred to as graviphotons (GPh) [2]. Dark matter is divided in two types: cold DM and hot DM with the cold DM being composed of neutralinos and hot DM – of neutrinos formed in stars. Generally speaking, the most of the results obtained are independent of hot and cold DM composition. DE is often identified with cosmological vacuum. As the percentage shows, vacuum density is in excess of the total density of the rest types of cosmic energy. Since vacuum causes antigravitation, the Universe expands with acceleration [3]. Hereinafter, use is made of the designations adopted in [4]. 2. Let us consider the formation of a vacuum-dominated epoch. To this end, let us write the Einstein – Friedmann equation with acceleration [4] for the spatially flat Universe as follows: 34 . G aG a =− π ρ