Dynamical back-reaction of relic gravitons

TL;DR

This paper investigates how relic gravitons influence the dynamics of curvature bounces, revealing that their back-reaction effects are crucial for consistent bouncing cosmological models, especially at late times.

Contribution

It develops a general iterative framework to calculate dynamical back-reaction effects of relic gravitons in bouncing cosmologies, including analytical and numerical examples.

Findings

Back-reaction effects are significant at short wavelengths.

Dynamical back-reaction is essential for consistent bouncing models.

Analytical and numerical results support the importance of back-reaction.

Abstract

The dynamical effects of the tensor modes of the geometry are investigated in the context of curvature bounces. Since the bouncing behaviour implies sharp deviations from a radiation-dominated evolution, significant back-reaction effects of relic gravitons may be expected at short wavelengths. After developing a general iterative framework for the calculation of dynamical back-reaction effects, explicit analytical and numerical examples are investigated for different parametrizations of the energy-momentum pseudo-tensor(s) of the produced gravitons. The reported results suggest that dynamical back-reaction effects are a necessary ingredient for a consistent description of bouncing models at late times.