Imprints of Large-Scale Structures in the Anisotropies of the Cosmological Gravitational Wave Background

2025/05/21 by Rafael Bravo, Bravo, Rafael, Walter Riquelme +1 · 1 voice · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Geophysics and Gravity Measurements #High Energy Physics - Theory (hep-th) #Relativity and Gravitational Theory #astro-ph.CO #gr-qc #hep-th

paper · pdf · doi:10.48550/arxiv.2505.15084

openalex publication_date 2025/05/21 · arxiv published 2025/05/21 · arxiv updated 2025/05/21 · openalex created_date 2025/10/19 · openalex updated_date 2026/07/28

Abstract

We compute the cross-correlation between the anisotropies of the cosmological gravitational wave background (CGWB) and the galaxy density contrast. We show that the cross-correlation is non-zero due to the \it late integrated Sachs-Wolfe (ISW) effect experienced by tensor modes. We study the detection prospects of the cross-correlation signal against cosmic variance (CV), and in the light of incoming LSS and GW surveys, where we found that the signal under certain conditions could be distinguishable from noise. In addition, by considering a CGWB sourced by scalar-induced gravitational waves, and the inclusion of a scale-dependent galaxy bias, we use the cross-correlation to forecast local primordial non-Gaussianity, where we find σ(f_NL^loc)∼10 for CV only and a LSST-like survey. Moreover, by combining the Fisher information of CGWB×LSS with LSS, we are able to improve the constraints by 4% compared to an LSS-only analysis. Our results imply that a cross-correlation between GW anisotropies and LSS can indeed come from a stochastic background of cosmological origin and could be used to distinguish it from an astrophysical one.

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Cited by

• Isotropy, anisotropies and non-Gaussianity in the scalar-induced gravitational-wave background: diagrammatic approach for primordial non-Gaussianity up to arbitrary order

Discussions

• From last week arXiv! Check our new paper (with @rafalafelo.bsky.social) on how Cosmological Gravitational Waves could correlate with Large-Scale Structures, and its potential synergies with Primordia [bsky, 3 points, 0 comments]

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