Eliminating the Hubble Tension in the Presence of the Interconnection between Dark Energy and Matter in the Modern Universe

Abstract

It is accepted in modern cosmology that the scalar field responsible for the inflationary stage of the early Universe is completely transformed into matter. It is assumed that the accelerated expansion is currently driven by dark energy (DE), which is likely determined by Einstein’s cosmological constant, unrelated to the scalar field responsible for inflation. We consider a cosmological model in which DE can currently have two components, one of which is Einstein’s constant ($\Lambda$) and the other, smaller dark energy variable component DEV (${{\Lambda }_{V}}$), is associated with the remnant of the scalar field that caused inflation after the main part of the scalar field has turned into matter. We consider only the stages of evolution of the Universe after recombination ($z \lesssim 1100$), where dark matter (DM) is the predominant component of matter. It is assumed that the transformation of the scalar field into matter continues at the present time and is accompanied by the reverse process of the transformation of DM into a scalar field. The interconnection between DM and DEV, which leads to a linear relationship between the energy densities of these components after recombination ${{\rho }_{{{\text{DM}}}}} = \alpha {\kern 1pt} {{\rho }_{{{\text{DEV}}}}}$, is considered. Variants with a dependence of the coefficient $\alpha (z)$ on the redshift $z$ are also considered. One of the problems that have arisen in modern cosmology, called Hubble Tension (HT), is the discrepancy between the present values of the Hubble constant (${{H}_{0}}$) measured from observations of the Universe at small redshifts ($z \lesssim 1$) and the values found from fluctuations of the cosmic microwave background in the Universe at large redshifts ($z \approx 1100$). In the model under consideration, this discrepancy can be explained by the deviation of the existing cosmological model from the conventional $\Lambda$ cold dark matter (CDM) model of the flat Universe by the action of the additional dark energy component DEV at the stages after recombination. Within this extended model, we consider various $\alpha {\kern 1pt} (z)$ functions that can eliminate the HT. To maintain the ratio of DEV and DM energy densities close to constant over the interval $0 \leqslant z \lesssim 1100$, it is necessary to assume the existence of a wide spectrum of dark matter particle masses.