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Bridging the μhz Gap in the Gravitational-Wave Landscape with Binary Resonances

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Original languageEnglish
Article number101103
JournalPhysical Review Letters
Issue number10
Published11 Mar 2022

Bibliographical note

Funding Information: We thank Vitor Cardoso, Jordi Miralda-Escudé, James Millen, Joe Romano, and two anonymous referees for valuable feedback on this work. We are grateful to Richard Brito for sharing with us the SGWB spectra from ultralight bosons shown in Fig. , and to Marek Lewicki for providing us with the AION-km PI curve and enlightening us about FOPTs. We acknowledge the use of numpy and scipy in our python code, as well as the MCMC sampler emcee in producing the FOPT exclusion regions. Figure , and Figs. 1–3 in the Supplemental Material, were produced using matplotlib , while Fig. was produced using corner . py . A. C. J. was supported by King’s College London through a Graduate Teaching Scholarship. D. B. is supported by a Ayuda Beatriz Galindo Senior from the Spanish Ministerio de Universidades, Grant No. BG20/00228. D. B. acknowledges support from the Fundación Jesus Serra and the Instituto de Astrofísica de Canarias under the Visiting Researcher Programme 2021 agreed between both institutions. D. B. also acknowledges the hospitality of the Theoretical Physics Department of Universidad de Zaragoza. Publisher Copyright: © 2022 American Physical Society.

King's Authors


Gravitational-wave (GW) astronomy is transforming our understanding of the Universe by probing phenomena invisible to electromagnetic observatories. A comprehensive exploration of the GW frequency spectrum is essential to fully harness this potential. Remarkably, current methods have left the μHz frequency band almost untouched. Here, we show that this μHz gap can be filled by searching for deviations in the orbits of binary systems caused by their resonant interaction with GWs. In particular, we show that laser ranging of the Moon and artificial satellites around the Earth, as well as timing of binary pulsars, may discover the first GW signals in this band, or otherwise set stringent new constraints. To illustrate the discovery potential of these binary resonance searches, we consider the GW signal from a cosmological first-order phase transition, showing that our methods will probe models of the early Universe that are inaccessible to any other near-future GW mission. We also discuss how our methods can shed light on the possible GW signal detected by NANOGrav, either constraining its spectral properties or even giving an independent confirmation.

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