The unified history of the viscous accelerating universe and phase transitions

TL;DR

This paper presents a unified model of cosmic inflation and dark energy using viscous fluid dynamics with phase transitions, aligning with observational data and offering insights into dark matter.

Contribution

It introduces a novel viscous fluid model with phase transitions to unify early inflation and late-time acceleration in cosmology.

Findings

Model fits observational data for cosmic expansion

Describes spectral index and tensor-to-scalar ratio consistent with observations

Proposes a scenario addressing dark matter problem

Abstract

We propose the unified description of the early acceleration (cosmological inflation) and the present epoch of so called "dark energy". The inflation can be described by cosmic fluid with van der Waals equation of state and with viscosity term. Viscosity leads to slow-roll inflation with the parameters such as the spectral index, and the tensor-to-scalar ratio in concordance with observational data. Our next step is to modify this equation of state (EoS) to describe the present accelerated expansion. One can add the term into EoS so that the contribution of which is small for inflation but crucial for late-time acceleration. The key point of the model is possible phase transition which leads to decrease of the viscosity. We show that proposed model describes observational data about standard "candles" and correct dependence of Hubble parameter from redshift. Moreover, we propose the possible scenario to resolve dark matter problem.