Detecting a relic background of scalar waves with LIGO

TL;DR

This paper explores the potential for LIGO detectors to identify a stochastic background of massive scalar particles, which could produce signals comparable to gravitational wave backgrounds if their frequency matches detector sensitivity.

Contribution

It introduces a method to detect non-relativistic scalar backgrounds with LIGO, considering their spectral contribution and potential to influence cosmological energy density.

Findings

Scalar background can produce detectable signals in LIGO if within sensitivity band.

Non-relativistic scalar spectrum could significantly contribute to the Universe's energy density.

Scalar signals may compete with gravitational wave backgrounds in detection scenarios.

Abstract

We discuss the possible detection of a stochastic background of massive, non-relativistic scalar particles, through the cross correlation of the two LIGO interferometers in the initial, enhanced and advanced configuration. If the frequency corresponding to the mass of the scalar field lies in the detector sensitivity band, and the non-relativistic branch of the spectrum gives a significant contribution to energy density required to close the Universe, we find that the scalar background can induce a non-negligible signal, in competition with a possible signal produced by a stochastic background of gravitational radiation.