Relic gravitons from super-inflation

TL;DR

This paper investigates gravitational wave production during the super-inflationary phase predicted by Loop Quantum Cosmology, emphasizing the importance of a subsequent standard inflationary phase to align with observational bounds.

Contribution

It analyzes graviton creation during super-inflation with inverse volume corrections and highlights the necessity of standard inflation to prevent excessive graviton amplitudes.

Findings

Graviton spectrum amplitude depends on post-super-inflation evolution.

Without standard inflation, graviton intensity would be unacceptably high.

Standard inflation reduces graviton abundance to acceptable levels.

Abstract

The super-inflationary phase is predicted by the Loop Quantum Cosmology. In this paper we study the creation of gravitational waves during this phase. We consider the inverse volume corrections to the equation for the tensor modes and calculate the spectrum of the produced gravitons. The amplitude of the obtained spectrum as well as maximal energy of gravitons strongly depend on the evolution of the Universe after the super-inflation. We show that a further standard inflationary phase is necessary to lower the amount of gravitons below the present bound. In case of the lack of the standard inflationary phase, the present intensity of gravitons would be extremely large. These considerations give us another motivation to introduce the standard phase of inflation.