Cosmological aspects of a unified dark energy and dust dark matter model

TL;DR

This paper tests a modified gravity and scalar field model that unifies dark energy and dark matter, fitting observational data and predicting diverse future universe scenarios including phase transitions.

Contribution

It introduces and tests a novel model unifying dark energy and dark matter using modified gravity and scalar fields, with detailed analysis of universe evolution scenarios.

Findings

Model fits supernovae data well

Allows various universe expansion scenarios

Predicts possible phase transitions in the universe

Abstract

Recently, a model of modified gravity plus single scalar field model was proposed, in which the scalar couples both to the standard Riemannian volume form given by the square root of the determinant of the Riemannian metric, as well as to another non-Riemannian volume form given in terms of an auxiliary maximal rank antisymmetric tensor gauge field. This model provides an exact unified description of both dark energy (via dynamically generated cosmological constant) and dark matter (as a "dust" fluid due to a hidden nonlinear Noether symmetry). In this paper we test the model against Supernovae type Ia experimental data and investigate the future Universe evolution which follows from it. Our results show that this model has very interesting features allowing various scenarios of Universe evolution and in the same time perfectly fits contemporary observational data. It can describe exponentially expanding or finite expanding Universe and moreover, a Universe with phase transition of first kind. The phase transition occurs to a new, emerging at some time ground state with lower energy density, which affects significantly the Universe evolution.