The maximum mass ratio of hierarchical binary black hole mergers may cause the $q$-$χ_{\rm eff}$ correlation

Fuente: arXiv
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Main Authors: Vijaykumar, Aditya, Farah, Amanda M., Fishbach, Maya
Format: Preprint
Published: 2026
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author Vijaykumar, Aditya
Farah, Amanda M.
Fishbach, Maya
author_facet Vijaykumar, Aditya
Farah, Amanda M.
Fishbach, Maya
contents Regardless of their initial spins, the merger of two roughly equal mass black holes (BHs) produces a remnant BH of dimensionless spin $0.69$. Such remnants can merge with other BHs in dense stellar environments and produce hierarchical mergers. Analyzing the latest catalog binary black hole (BBH) mergers from the LIGO-Virgo-KAGRA detectors, we identify a subpopulation with primary spins consistent with such hierarchical mergers. Consistent with astrophysical expectations for mergers of second-generation BHs with first-generation BHs, we find that this subpopulation has mass ratios below $0.59^{+0.18}_{-0.23}$. We also infer that $19$-$88\%$ of the BBH population below this mass ratio is consistent with belonging to the hierarchically merged population. Our results offer a natural explanation for the narrowing of the effective inspiral spin distribution with mass ratio observed in other studies.
format Preprint
id arxiv_https___arxiv_org_abs_2601_03457
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The maximum mass ratio of hierarchical binary black hole mergers may cause the $q$-$χ_{\rm eff}$ correlation
Vijaykumar, Aditya
Farah, Amanda M.
Fishbach, Maya
High Energy Astrophysical Phenomena
Astrophysics of Galaxies
General Relativity and Quantum Cosmology
Regardless of their initial spins, the merger of two roughly equal mass black holes (BHs) produces a remnant BH of dimensionless spin $0.69$. Such remnants can merge with other BHs in dense stellar environments and produce hierarchical mergers. Analyzing the latest catalog binary black hole (BBH) mergers from the LIGO-Virgo-KAGRA detectors, we identify a subpopulation with primary spins consistent with such hierarchical mergers. Consistent with astrophysical expectations for mergers of second-generation BHs with first-generation BHs, we find that this subpopulation has mass ratios below $0.59^{+0.18}_{-0.23}$. We also infer that $19$-$88\%$ of the BBH population below this mass ratio is consistent with belonging to the hierarchically merged population. Our results offer a natural explanation for the narrowing of the effective inspiral spin distribution with mass ratio observed in other studies.
title The maximum mass ratio of hierarchical binary black hole mergers may cause the $q$-$χ_{\rm eff}$ correlation
topic High Energy Astrophysical Phenomena
Astrophysics of Galaxies
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2601.03457