A weakly modelled view of the joint compact-binary mass plane: population structure and spectral-siren cosmology
Abstract
We introduce a flexible mixture model for the joint source-frame component-mass distribution of compact binaries, inferred simultaneously with cosmology, together with a framework that identifies structures in the reconstructed density, quantifying their posterior stability, local prominence, and cosmological relevance. Applied to GWTC-5.0, the workflow clarifies several familiar and emergent structures. The ∼35 M⊙ feature is classified as a clear near-equal-mass peak despite an ambiguous interpretation in the primary-mass projection. A weaker unequal-mass concentration near (21,12) M⊙ is recovered frequently but with lower prominence. A tentative joint transition near 60 M⊙ appears at mildly unequal masses, with a more robust manifestation in the primary-mass projection. For cosmology, the two-dimensional mass model constraint on H0 is 33% narrower than a model that flexibly reconstructs only the primary mass, and only ∼ 10% wider than analyses based on strongly parameterized one-dimensional spectral structure. At the feature level, we show that the ∼10 M⊙ and ∼35 M⊙ concentrations depend on H0 mainly through a common scale which captures the entire ∼ (1+z) cosmological rescaling of both masses; the intermediate unequal-mass feature instead retains residual dependence in the orthogonal mass-ratio direction. More generally, we argue that population prominence, formal inclusion in an astrophysical feature catalogue, and cosmological relevance need not coincide. These results suggest that a genuinely two-dimensional view may be required to fully exploit spectral-siren information. Our workflow provides a reproducible way to detect population structure and identify which aspects of its geometry are associated with spectral-siren constraints. The feature finder is directly applicable to other population reconstructions.
Related
- Spectral sirens cosmology from binary black holes populations with sharper mass features
- Expanding the scope of dark siren cosmology: Inferring the population properties of gravitational wave-hosting galaxies
- Tensor–Spectral Cosmogenesis as a Special Case of χ‑Cosmology in the ZEBTS‑SUPER Framework
- Cosmology of self-interacting ultralight dark matter: simultaneous shifts in the Hubble constant and structure growth
- Near- to far-infrared spectral energy distribution analysis of interacting galaxies in Hickson compact groups 56 and Stephan’s Quintet (HCG 92)
BibTeX
@misc{renzis2026weakly,
title = {{A weakly modelled view of the joint compact-binary mass plane: population structure and spectral-siren cosmology}},
author = {Viola de Renzis and Alessandro Agapito and Michele Mancarella},
howpublished = {HAL},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.10535},
eprint = {2610.10535},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05835152v1},
note = {CC0},
}
RIS
TY - UNPB
TI - A weakly modelled view of the joint compact-binary mass plane: population structure and spectral-siren cosmology
AU - Viola de Renzis
AU - Alessandro Agapito
AU - Michele Mancarella
PY - 2026
DA - 2026/10/07
PB - HAL
DO - 10.48550/arxiv.2610.10535
UR - https://hal.science/hal-05835152v1
AB - We introduce a flexible mixture model for the joint source-frame component-mass distribution of compact binaries, inferred simultaneously with cosmology, together with a framework that identifies structures in the reconstructed density, quantifying their posterior stability, local prominence, and cosmological relevance. Applied to GWTC-5.0, the workflow clarifies several familiar and emergent structures. The ∼35 M_⊙ feature is classified as a clear near-equal-mass peak despite an ambiguous interpretation in the primary-mass projection. A weaker unequal-mass concentration near (21,12) M_⊙ is recovered frequently but with lower prominence. A tentative joint transition near 60 M_⊙ appears at mildly unequal masses, with a more robust manifestation in the primary-mass projection. For cosmology, the two-dimensional mass model constraint on H_0 is 33% narrower than a model that flexibly reconstructs only the primary mass, and only ∼ 10% wider than analyses based on strongly parameterized one-dimensional spectral structure. At the feature level, we show that the ∼10 M_⊙ and ∼35 M_⊙ concentrations depend on H_0 mainly through a common scale which captures the entire ∼ (1+z) cosmological rescaling of both masses; the intermediate unequal-mass feature instead retains residual dependence in the orthogonal mass-ratio direction. More generally, we argue that population prominence, formal inclusion in an astrophysical feature catalogue, and cosmological relevance need not coincide. These results suggest that a genuinely two-dimensional view may be required to fully exploit spectral-siren information. Our workflow provides a reproducible way to detect population structure and identify which aspects of its geometry are associated with spectral-siren constraints. The feature finder is directly applicable to other population reconstructions.
ER -