Gravitational waves from the Big Bounce

TL;DR

This paper analyzes gravitational wave production during the Big Bounce in Loop Quantum Cosmology, showing how holonomy corrections influence the spectrum and potential observable effects on CMB low multipoles.

Contribution

It provides an analytical solution for gravitational wave spectra in a simplified bounce model and explores implications for CMB observations within Loop Quantum Cosmology.

Findings

Holonomy corrections suppress gravitational wave creation.

The spectrum decreases to zero for low energy modes.

Potential explanation for low CMB multipoles suppression.

Abstract

In this paper we investigate gravitational waves production during the Big Bounce phase inspired by the Loop Quantum Cosmology. We consider the influence of the holonomy corrections to the equation for tensor modes. We show that they act like additional effective graviton mass, suppressing gravitational waves creation. However, this effects can be treated perturbatively. We investigate the simplified model without these corrections and find its exact analytical solution. For this model we calculate a spectrum of the gravitational waves from the Big Bounce phase. The obtained spectrum decreases to zero for the low energy modes. Based on this observation we indicate that this effect can lead to the low CMB multipoles suppression and gives a potential way to test Loop Quantum Cosmology models. We also consider a scenario with a post-bounce inflationary phase. The obtained power spectrum gives qualitative explanation of the CMB spectra, including low multipoles suppression. This result is a challenge to construct a consistent bounce+inflation model in the Loop Quantum Cosmology.