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Stochastic Gravitational-Wave Backgrounds: Current Detection Efforts and Future Prospects

Research output: Contribution to journalReview articlepeer-review

Arianna I. Renzini, Boris Goncharov, Alexander C. Jenkins, Patrick M. Meyers

Original languageEnglish
Article number34
Issue number1
PublishedFeb 2022

Bibliographical note

Funding Information: Funding: AIR acknowledges the support of the National Science Foundation and the LIGO Laboratory. BG is supported by the Italian Ministry of Education, University and Research within the PRIN 2017 Research Program Framework, n. 2017SYRTCN. PMM was supported by the NANOGrav Physics Frontiers Center, National Science Foundation (NSF), award number 2020265. Parts of this research were conducted by the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav), through project number CE170100004. Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

King's Authors


The collection of individually resolvable gravitational wave (GW) events makes up a tiny fraction of all GW signals that reach our detectors, while most lie below the confusion limit and are undetected. Similarly to voices in a crowded room, the collection of unresolved signals gives rise to a background that is well-described via stochastic variables and, hence, referred to as the stochastic GW background (SGWB). In this review, we provide an overview of stochastic GW signals and characterise them based on features of interest such as generation processes and observational properties. We then review the current detection strategies for stochastic backgrounds, offering a ready-to-use manual for stochastic GW searches in real data. In the process, we distinguish between interferometric measurements of GWs, either by ground-based or space-based laser interferometers, and timing-residuals analyses with pulsar timing arrays (PTAs). These detection methods have been applied to real data both by large GW collaborations and smaller research groups, and the most recent and instructive results are reported here. We close this review with an outlook on future observations with third generation detectors, space-based interferometers, and potential noninterferometric detection methods proposed in the literature.

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