Cosmological models described by a mixture of van der Waals fluid and dark energy

TL;DR

This paper models the universe using a mixture of van der Waals fluid and dark energy, capturing various cosmic evolution phases including inflation, matter domination, and current acceleration.

Contribution

It introduces a novel cosmological model combining van der Waals fluid with dark energy, accounting for irreversible energy transfer processes.

Findings

Simulates inflationary, matter-dominated, and accelerated expansion phases.

Shows van der Waals fluid can act as an inflaton.

Demonstrates dark energy dominance in the current universe.

Abstract

The Universe is modeled as a binary mixture whose constituents are described by a van der Waals fluid and by a dark energy density. The dark energy density is considered either as the quintessence or as the Chaplygin gas. The irreversible processes concerning the energy transfer between the van der Waals fluid and the gravitational field are taken into account. This model can simulate: (a) an inflationary period where the acceleration grows exponentially and the van der Waals fluid behaves like an inflaton; (b) an inflationary period where the acceleration is positive but it decreases and tends to zero whereas the energy density of the van der Waals fluid decays; (c) a decelerated period which corresponds to a matter dominated period with a non-negative pressure; and (d) a present accelerated period where the dark energy density outweighs the energy density of the van der Waals fluid.