Trends in the Population of Binary Black Holes Following the Fourth Gravitational-wave Transient Catalog: A Data-driven Analysis
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1.
Monash University
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2.
ARC Centre of Excellence for Gravitational Wave Discovery
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3.
California Institute of Technology
Abstract
Current models of binary black hole distributions are difficult to interpret because inferences hinge on modeling choices, which can mask or mimic real structure. The maximum population likelihood " formalism" provides a means to investigate features in the distribution of binary black holes using only data—no model required. It tells us whether inferred features are truly present in the data or whether they arise from model misspecification. It also provides guidance for developing new models by highlighting previously unnoticed features. We utilize the π formalism to examine the binary black hole population in the LIGO–Virgo–KAGRA (LVK) Gravitational-Wave Transient Catalog (GWTC-4). Our analysis supports the existence of a gap around 45 M⊙ in the secondary black hole mass distribution and identifies a widening in the distribution of the effective inspiral spin parameter χ eff at ≈45 M⊙ as recently reported by H. Tong et al. We find support for a previously reported anticorrelation between χ eff and mass ratio. However, this may be a spurious correlation arising from misspecification of the joint distribution of black hole masses. Furthermore, we identify support for dimensionless black hole spin magnitudes at χ ≈ 0.2 and χ ≈ 0.7. The data support the existence of a correlation between spin magnitudes χ1 and χ2 , though subsequent study is required to determine whether this is statistically significant. The accompanying data release includes π samples, which can be used to compare theoretical predictions to LVK data and to assess assumptions in parameterized models.
Copyright and License
© 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Acknowledgement
This work is supported through the Australian Research Council (ARC) Centre of Excellence CE230100016, Discovery Projects DP220101610 and DP230103088, and LIEF Project LE210100002. We are grateful to Simon Stevenson, Christian Adamcewicz, and Sharan Banagiri for insightful discussions. We thank Jack Heinzel and Thomas Dent for feedback on an earlier draft of this manuscript.
This material is based on work supported by NSF’s LIGO Laboratory, which is a major facility fully funded by the National Science Foundation. The authors are grateful for computational resources provided by the LIGO Laboratory and supported by National Science Foundation grants PHY-0757058 and PHY-0823459.
This research has made use of data or software obtained from the Gravitational Wave Open Science Center (gw-openscience.org), a service of LIGO Laboratory, the LIGO Scientific Collaboration, the Virgo Collaboration, and KAGRA. LIGO Laboratory and Advanced LIGO are funded by the United States National Science Foundation (NSF), as well as the Science and Technology Facilities Council (STFC) of the United Kingdom, the Max-Planck-Society (MPS), and the State of Niedersachsen/Germany, in support of the construction of Advanced LIGO and construction and operation of the GEO600 detector. Additional support for Advanced LIGO was provided by the Australian Research Council. Virgo is funded, through the European Gravitational Observatory (EGO), by the French Centre National de Recherche Scientifique (CNRS), the Italian Istituto Nazionale di Fisica Nucleare (INFN), and the Dutch Nikhef, with contributions by institutions from Belgium, Germany, Greece, Hungary, Ireland, Japan, Monaco, Poland, Portugal, and Spain. The construction and operation of KAGRA are funded by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) and the Japan Society for the Promotion of Science (JSPS) in Japan, the National Research Foundation (NRF) and Ministry of Science and ICT (MSIT) in Korea, and the Academia Sinica (AS) and the Ministry of Science and Technology (MoST) in Taiwan.
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Guttman_2026_ApJ_996_144.pdf
Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2509.09876 (arXiv)
- Is supplemented by
- Dataset: 10.5281/zenodo.17096730 (DOI)
Funding
- Australian Research Council
- CE230100016
- Australian Research Council
- DP220101610
- Australian Research Council
- DP230103088
- Australian Research Council
- LE210100002
- National Science Foundation
- PHY-0757058
- National Science Foundation
- PHY-0823459
Dates
- Submitted
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2025-09-11
- Accepted
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2025-10-23
- Available
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2026-01-09Published
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- Caltech groups
- LIGO , Division of Physics, Mathematics and Astronomy (PMA)
- Publication Status
- Published