Perturbations for transient acceleration

TL;DR

This paper investigates the possibility of a finite, transient phase of cosmic acceleration that eventually transitions back to deceleration, analyzing both background and perturbation dynamics in light of current observational data.

Contribution

It extends previous homogeneous models by including dark energy perturbations and tests the transient acceleration scenario against multiple observational datasets.

Findings

Transient acceleration is consistent with current data.

Dark energy perturbations can influence the dynamics of cosmic acceleration.

The model fits supernova, growth rate, and galaxy survey data.

Abstract

According to the standard $\Lambda$CDM model, the accelerated expansion of the Universe will go on forever. Motivated by recent observational results, we explore the possibility of a finite phase of acceleration which asymptotically approaches another period of decelerated expansion. Extending an earlier study on a corresponding homogeneous and isotropic dynamics, in which interactions between dark matter and dark energy are crucial, the present paper also investigates the dynamics of the matter perturbations both on the Newtonian and GR levels and quantifies the potential relevance of perturbations of the dark-energy component. In the background, the model is tested against the Supernova type Ia (SNIa) data of the Constitution set and on the perturbative level against growth rate data and the data of the 2dFGRS project. Our results indicate, that a transient phase of accelerated expansion is not excluded by current observations.