Primordial gravitational waves : a probe of the early universe

TL;DR

This paper explores how upcoming gravitational wave detectors could observe signals from the early universe, providing insights into phenomena like phase transitions and cosmic strings that shaped the cosmos.

Contribution

It identifies potential primordial gravitational wave sources detectable by next-generation instruments, advancing understanding of the early universe's physical processes.

Findings

Detection of stochastic gravitational wave background is feasible for certain early universe scenarios.

Strongly first-order phase transitions and cosmic string networks are promising sources within detector sensitivity.

Other primordial backgrounds remain beyond current detection capabilities.

Abstract

We discuss the potential cosmological role of gravitational wave astronomy as a probe of the very early universe. The next generation of detectors - now in production - may be able to observe a stochastic background of gravitational waves produced by violent processes during the earliest moments after the creation of the universe. Viable theoretical scenarios within detector sensitivity include strongly first-order phase transitions, possibly at the end of inflation, and networks of cosmic strings. At this stage, other primordial backgrounds from slow-roll inflation, global topological defects and the standard electroweak phase transition appear to be out of range. The discovery of any of the possible cosmological sources will have enormous implications for our understanding of the very early universe and for fundamental physics at the highest energies.