Multi-band cross-correlation dark sirens: enhancing cosmological parameter and gravitational-wave bias constraints
Abstract
Multi-band gravitational-wave (GW) observation, combining space-borne and ground-based detectors across different frequency bands, can improve the sky localization of compact binary sources by two to three orders of magnitude compared to single-band detection. This enhancement is crucial for cross-correlation dark siren analyses, since the sky localization uncertainty directly determines the noise level of the GW angular power spectrum. In this work, we present the first Fisher forecast for cross-correlation dark siren cosmology with multi-band GW observations, cross-correlating GW events from the Einstein Telescope (ET), Cosmic Explorer (CE), and B-DECIGO with the Chinese Space-station Survey Telescope photometric galaxy survey. We compare three network configurations: the multi-band B-DECIGO+ET+2CE (BDET2CE), the ground-only ET+2CE (ET2CE), and B-DECIGO alone. In the ΛCDM model, BDET2CE achieves σ(h)/h = 0.35%, improving by 37% over the ground-only ET2CE (0.55%) and by 86% over B-DECIGO alone (2.45%). Extending to the w0waCDM framework, the multi-band advantage on cosmological parameters becomes more moderate, with BDET2CE improving σ(h)/h by ∼ 4% over ET2CE and ∼ 22% over B-DECIGO. The most striking advantage of multi-band observation lies in the per-bin measurement of the GW clustering bias bGW(z): at z ∼ 1−2, BDET2CE constrains the bias to ∼ 3% precision, compared to ∼ 8−60% for ET2CE and ∼ 20−33% for B-DECIGO. These precise, redshift-resolved bias measurements open a new avenue for probing the astrophysics of compact binary mergers, enabling constraints on formation channels such as isolated binary evolution and dynamical assembly that predict distinct clustering signatures.
Versions
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BibTeX
@misc{song2026multiband,
title = {{Multi-band cross-correlation dark sirens: enhancing cosmological parameter and gravitational-wave bias constraints}},
author = {Ji-Yu Song and Ya-Nan Du and Yue-Yan Dong and Jing-Fei Zhang and Xin Zhang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.15844},
eprint = {2606.15844},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.15844},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Multi-band cross-correlation dark sirens: enhancing cosmological parameter and gravitational-wave bias constraints
AU - Ji-Yu Song
AU - Ya-Nan Du
AU - Yue-Yan Dong
AU - Jing-Fei Zhang
AU - Xin Zhang
PY - 2026
DA - 2026/09/09
PB - arXiv
DO - 10.48550/arxiv.2606.15844
UR - https://arxiv.org/abs/2606.15844
AB - Multi-band gravitational-wave (GW) observation, combining space-borne and ground-based detectors across different frequency bands, can improve the sky localization of compact binary sources by two to three orders of magnitude compared to single-band detection. This enhancement is crucial for cross-correlation dark siren analyses, since the sky localization uncertainty directly determines the noise level of the GW angular power spectrum. In this work, we present the first Fisher forecast for cross-correlation dark siren cosmology with multi-band GW observations, cross-correlating GW events from the Einstein Telescope (ET), Cosmic Explorer (CE), and B-DECIGO with the Chinese Space-station Survey Telescope photometric galaxy survey. We compare three network configurations: the multi-band B-DECIGO+ET+2CE (BDET2CE), the ground-only ET+2CE (ET2CE), and B-DECIGO alone. In the ΛCDM model, BDET2CE achieves σ(h)/h = 0.35%, improving by 37% over the ground-only ET2CE (0.55%) and by 86% over B-DECIGO alone (2.45%). Extending to the w_0w_aCDM framework, the multi-band advantage on cosmological parameters becomes more moderate, with BDET2CE improving σ(h)/h by ∼ 4% over ET2CE and ∼ 22% over B-DECIGO. The most striking advantage of multi-band observation lies in the per-bin measurement of the GW clustering bias b_GW(z): at z ∼ 1−2, BDET2CE constrains the bias to ∼ 3% precision, compared to ∼ 8−60% for ET2CE and ∼ 20−33% for B-DECIGO. These precise, redshift-resolved bias measurements open a new avenue for probing the astrophysics of compact binary mergers, enabling constraints on formation channels such as isolated binary evolution and dynamical assembly that predict distinct clustering signatures.
ER -