Bouncing cosmologies with dark matter and dark energy

TL;DR

This paper reviews bouncing cosmologies involving dark matter and dark energy, highlighting their predictions for the power spectrum and potential falsifiability through future observations.

Contribution

It introduces matter bounce scenarios with dark components, emphasizing their unique predictions like positive running of the scalar index and discussing their theoretical foundations.

Findings

Predict a nearly scale-invariant power spectrum with a slight red tilt

Forecast a small tensor-to-scalar ratio in these models

Predict a positive running of the scalar index, distinguishable from inflationary models

Abstract

We review matter bounce scenarios where the matter content is dark matter and dark energy. These cosmologies predict a nearly scale-invariant power spectrum with a slightly red tilt for scalar perturbations and a small tensor-to-scalar ratio. Importantly, these models predict a positive running of the scalar index, contrary to the predictions of the simplest inflationary and ekpyrotic models, and hence could potentially be falsified by future observations. We also review how bouncing cosmological space-times can arise in theories where either the Einstein equations are modified or where matter fields that violate the null energy condition are included.