Probing the pre-BBN universe with gravitational waves from cosmic strings

TL;DR

This paper explores how gravitational wave signals from cosmic strings can reveal the properties of the early universe before BBN, potentially detecting non-standard states or new physics beyond current experimental reach.

Contribution

It demonstrates how the gravitational wave spectrum from cosmic strings can test the pre-BBN universe's equation of state and evolution, offering a new probe of early universe physics.

Findings

Current and future gravitational wave detectors can detect signals indicating non-standard early universe conditions.

The spectrum of gravitational waves from cosmic strings can distinguish different pre-BBN cosmological models.

Detection of such signals can reveal new degrees of freedom active in the early universe.

Abstract

Many motivated extensions of the Standard Model predict the existence of cosmic strings. Gravitational waves originating from the dynamics of the resulting cosmic string network have the ability to probe many otherwise inaccessible properties of the early universe. In this study we show how the spectrum of gravitational waves from a cosmic string network can be used to test the equation of state of the early universe prior to Big Bang Nucleosynthesis (BBN). We also demonstrate that current and planned gravitational wave detectors such as LIGO, LISA, DECIGO/BBO, and ET/CE have the potential to detect signals of a non-standard pre-BBN equation of state and evolution of the early universe (e.g., early non-standard matter domination or kination domination) or new degrees of freedom active in the early universe beyond the sensitivity of terrestrial collider experiments and cosmic microwave background measurements.