Gravitational Wave Backgrounds from Colliding ECOs

TL;DR

This paper explores the potential of long baseline atom interferometers to detect the gravitational wave background from various sources, including stellar binaries and dark sector objects, revealing new insights into the universe.

Contribution

It surveys possible gravitational wave background sources in the mid-frequency band and highlights their detectability with proposed atom interferometer experiments.

Findings

Stellar-mass binary inspirals produce detectable signals for AION-km and AEDGE.

Dark sector exotic objects could generate unique gravitational wave signatures.

Mid-frequency detectors can reveal new aspects of the universe and dark sector.

Abstract

Long baseline atom interferometers offer an exciting opportunity to explore mid-frequency gravitational waves. In this work we survey the landscape of possible contributions to the total 'gravitational wave background' in this frequency band and advocate for targeting this observable. Such an approach is complimentary to searches for resolved mergers from individual sources and may have much to reveal about the Universe. We find that the inspiral phases of stellar-mass compact binaries cumulatively produce a signal well within reach of the proposed AION-km and AEDGE experiments. Hypothetical populations of dark sector exotic compact objects, harbouring just a tiny fraction of the dark energy density, could also generate signatures unique to mid- and low-frequency gravitational wave detectors, providing a novel means to probe complexity in the dark sector.