Luminosity-weighted galaxy and gravitational wave cross-correlations
Abstract
Cross-correlations of galaxies and gravitational waves (GW) can be used to extract cosmological parameters and the gravitational wave bias. In this work, we study how to include galaxy luminosities in these spatial cross-correlations, inspired by the standard approach of dark sirens line-of-sight redshift priors. We present a formalism to include luminosity information in galaxy-GW simulations and study the effects of assigning a hosting probability that depends on luminosity through a simple power law phost ∝ Lβ with β∈ {0,1,2} corresponding to uniformly, linear and quadratically weighted in luminosity. This effectively changes the GW linear bias with respect to dark matter and, in principle, allows to gain signal-to-noise and a sharper measurement of cosmological parameters. For a realistic luminosity dependence of the galaxy bias taken from DESI data, the gain is marginal, making the method robust to different luminosity weighting prescriptions. We show that the cross-correlation inference is able to recover the injected GW bias within 10% if there is a mismatch between the injected linear bias of host galaxies and observed galaxies, provided that one sticks to relatively large scales. We also show that the Hubble constant and matter energy density can be recovered to 0.5% and 5% respectively with a third generation network of GW detectors, regardless of the modeling of the GW bias.
Related
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BibTeX
@misc{dalang2026luminosityweighted,
title = {{Luminosity-weighted galaxy and gravitational wave cross-correlations}},
author = {Charles Dalang and Isabela Santiago de Matos and João Ferri and Raul Abramo and Tessa Baker},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.32436},
eprint = {2610.32436},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.32436},
}
RIS
TY - UNPB
TI - Luminosity-weighted galaxy and gravitational wave cross-correlations
AU - Charles Dalang
AU - Isabela Santiago de Matos
AU - João Ferri
AU - Raul Abramo
AU - Tessa Baker
PY - 2026
DA - 2026/10/23
PB - arXiv
DO - 10.48550/arxiv.2610.32436
UR - https://arxiv.org/abs/2610.32436
AB - Cross-correlations of galaxies and gravitational waves (GW) can be used to extract cosmological parameters and the gravitational wave bias. In this work, we study how to include galaxy luminosities in these spatial cross-correlations, inspired by the standard approach of dark sirens line-of-sight redshift priors. We present a formalism to include luminosity information in galaxy-GW simulations and study the effects of assigning a hosting probability that depends on luminosity through a simple power law p_host ∝ L^β with β∈ {0,1,2} corresponding to uniformly, linear and quadratically weighted in luminosity. This effectively changes the GW linear bias with respect to dark matter and, in principle, allows to gain signal-to-noise and a sharper measurement of cosmological parameters. For a realistic luminosity dependence of the galaxy bias taken from DESI data, the gain is marginal, making the method robust to different luminosity weighting prescriptions. We show that the cross-correlation inference is able to recover the injected GW bias within 10% if there is a mismatch between the injected linear bias of host galaxies and observed galaxies, provided that one sticks to relatively large scales. We also show that the Hubble constant and matter energy density can be recovered to 0.5% and 5% respectively with a third generation network of GW detectors, regardless of the modeling of the GW bias.
ER -