Inflationary gravitational waves and exotic pre Big Bang Nucleosynthesis cosmology

TL;DR

This paper explores how exotic pre-Big Bang phases could delay standard cosmology's onset and impact inflationary gravitational wave predictions, especially the tensor-to-scalar ratio, challenging current understanding.

Contribution

It investigates the effects of non-standard cosmological phases on inflationary gravitational wave signatures and their implications for cosmological models.

Findings

Exotic phases can significantly modify the tensor-to-scalar ratio.

Pre-Big Bang phases may delay the start of standard cosmology.

Alterations could impact the interpretation of inflationary gravitational wave data.

Abstract

According to the most popular scenario, the early Universe should have experienced an accelerated expansion phase, called Cosmological Inflation, after which the standard Big Bang Cosmology would have taken place giving rise to the radiation-dominated epoch. However, the details of the inflationary scenario are far to be completely understood. Thus, in this paper we study if possible additional (exotic) cosmological phases could delay the beginning of the standard Big Bang history and alter some theoretical predictions related to the inflationary cosmological perturbations, like, for instance, the order of magnitude of the tensor-to-scalar ratio $r$.