Exploring the Early Universe with Gaia and THEIA

TL;DR

Gaia and THEIA can explore early universe phenomena like phase transitions, primordial black holes, and topological defects through gravitational wave detection, offering insights into cosmology and recent NANOGrav findings.

Contribution

This paper highlights the potential of Gaia and THEIA to detect gravitational waves from early universe events, expanding their use beyond traditional astrometry.

Findings

Gaia and THEIA can detect gravitational waves from early universe phase transitions.

Potential to identify primordial black holes formed during these transitions.

Capability to probe topological defects and relate to NANOGrav results.

Abstract

It has recently been pointed out that Gaia is capable of detecting a stochastic gravitational wave background in the sensitivity band between the frequency of pulsar timing arrays and LISA. We argue that Gaia and THEIA has great potential for early universe cosmology, since such a frequency range is ideal for probing phase transitions in asymmetric dark matter, SIMP and the cosmological QCD transition. Furthermore, there is the potential for detecting primordial black holes in the solar mass range produced during such an early universe transition and distinguish them from those expected from the QCD epoch. Finally, we discuss the potential for Gaia and THEIA to probe topological defects and the ability of Gaia to potentially shed light on the recent NANOGrav results.