Physics-based phenomenological modeling of binary black hole hierarchical formation 1: Synthetic universes from globular cluster simulations for GWTC
Abstract
We iteratively model the GWTC-5.0 binary-black-hole census with three components. First, a physically normalized population from Rapster globular-cluster simulations spans cluster mass, metallicity, formation redshift, compactness, and natal black-hole spin. Hierarchical mergers reproduce higher-mass events and their larger effective-spin dispersion, provided black holes are born with zero natal spin. Second, a phenomenological field (isolated-binary) channel supplies the low-mass, preferentially aligned population. Its inclusion flattens the cluster compactness likelihood, permitting ordinary dense globular-cluster birth radii without requiring nuclear-cluster-like conditions. Finally, residual tension at $15−−30 M_\odot$ motivates an intermediate-mass isotropic component representing field remnants reprocessed in clusters. This is a hypothesis, not a detection: current numerical support precludes a reliable evidence comparison. Physical normalization converts the high-mass rate into f̂GC≃0.39%, with local rates Rcl≃9.1 and Rfield≃16.0 Gpc−3 yr−1. The model predicts linked mass-spectrum breaks near $35$ and 70 M⊙, a q≃0.5 feature from first-plus-second-generation pairings, and a symmetric effective-spin distribution that broadens sharply above 45 M⊙. These correlated, mass-resolved predictions can be tested as the gravitational-wave census grows.
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BibTeX
@misc{oshaughnessy2026physicsbased,
title = {{Physics-based phenomenological modeling of binary black hole hierarchical formation 1: Synthetic universes from globular cluster simulations for GWTC}},
author = {R. O'Shaughnessy and R. Mechum and M. Qazalbash and Z. Rosenberg and M. Zeeshan},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.05996},
eprint = {2609.05996},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.05996},
}
RIS
TY - UNPB
TI - Physics-based phenomenological modeling of binary black hole hierarchical formation 1: Synthetic universes from globular cluster simulations for GWTC
AU - R. O'Shaughnessy
AU - R. Mechum
AU - M. Qazalbash
AU - Z. Rosenberg
AU - M. Zeeshan
PY - 2026
DA - 2026/09/05
PB - arXiv
DO - 10.48550/arxiv.2609.05996
UR - https://arxiv.org/abs/2609.05996
AB - We iteratively model the GWTC-5.0 binary-black-hole census with three components. First, a physically normalized population from Rapster globular-cluster simulations spans cluster mass, metallicity, formation redshift, compactness, and natal black-hole spin. Hierarchical mergers reproduce higher-mass events and their larger effective-spin dispersion, provided black holes are born with zero natal spin. Second, a phenomenological field (isolated-binary) channel supplies the low-mass, preferentially aligned population. Its inclusion flattens the cluster compactness likelihood, permitting ordinary dense globular-cluster birth radii without requiring nuclear-cluster-like conditions. Finally, residual tension at $15−−30 M_\odot$ motivates an intermediate-mass isotropic component representing field remnants reprocessed in clusters. This is a hypothesis, not a detection: current numerical support precludes a reliable evidence comparison. Physical normalization converts the high-mass rate into f̂_GC≃0.39%, with local rates R_cl≃9.1 and R_field≃16.0 Gpc^−3 yr^−1. The model predicts linked mass-spectrum breaks near $35$ and 70 M_⊙, a q≃0.5 feature from first-plus-second-generation pairings, and a symmetric effective-spin distribution that broadens sharply above 45 M_⊙. These correlated, mass-resolved predictions can be tested as the gravitational-wave census grows.
ER -