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arXiv · 2603.06792

Spectral sirens cosmology from binary black holes populations with sharper mass features

Tom Bertheas·Vasco Gennari·Danièle Steer·Nicola Tamanini
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Abstract

Spectral-sirens inference enables the extraction of cosmological parameters from gravitational-wave data alone, without electromagnetic counterparts or galaxy catalogs. We introduce new parametric mass functions for the binary black hole population built as linear combination of truncated power-laws that capture significant structure across the mass spectrum. On analysing the latest gravitational-wave transient catalog, GWTC-4.0, we show that power-laws-only population models constrain the Hubble constant to $H_0 = 53.3^{+14.0}_{-10.8} ~\rm km \,s^{-1} \,Mpc^{-1}$ at $68\%$ confidence level. After probing the robustness of the results with respect to several modelling assumptions, we further test alternative cosmological models, establishing competitive constraints on modified gravitational-wave propagation, while bounds on the dark energy equation-of-state parameters remain uninformative. Projecting to the future O5 observing run with larger datasets at higher redshifts, we forecast substantial improvements in $H_0$ and modified propagation parameters. Our results highlight the strong interplay between the black hole mass distribution and inferred cosmology.

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Tom Bertheas, Vasco Gennari, Danièle Steer, Nicola Tamanini. 2026-09-11. Spectral sirens cosmology from binary black holes populations with sharper mass features. https://doi.org/10.1088/1475-7516%2F2026%2F09%2F045

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