dorsal/arxiv
View SchemaSignatures of a subpopulation of hierarchical mergers in the GWTC-4 gravitational-wave dataset
| Authors | Cailin Plunkett, Thomas Callister, Michael Zevin, Salvatore Vitale |
|---|---|
| Categories | |
| ArXiv ID | 2601.07908vv1 |
| URL | https://arxiv.org/abs/2601.07908 |
| License | http://creativecommons.org/licenses/by-nc-sa/4.0/ |
Abstract
Repeated black-hole mergers in dense stellar clusters are a plausible mechanism to populate the predicted gap in black hole masses due to the pair-instability process. These hierarchical mergers carry distinct spin and tilt features relative to first-generation black holes, for which previous studies have found evidence at a population level by interpreting features in the effective inspiral spin domain. We introduce an astrophysically-motivated model in the joint space of effective inspiral and precessing spins, which captures the dominant spin dynamics expected for hierarchical mergers. We find decisive evidence both for a population transition above $\sim 45M_\odot$, consistent with the anticipated onset of the pair-instability gap, as well as a peak at $\sim 15 M_\odot$, which we interpret as the global peak in the hierarchical merger rate. The existence of low- and high-mass subpopulations of higher-generation black holes suggests the contribution of both near-solar-metallicity and metal-poor star clusters to the hierarchical merger population. Our results reinforce the growing evidence for detailed, mass-dependent substructure in the spin distribution of the binary black hole population.
{
"annotation_id": "ec8c7202-8e5e-4e14-a8d5-c78d93c26541",
"date_created": "2026-02-17T05:53:12.330000Z",
"date_modified": "2026-02-17T05:53:12.330000Z",
"file_hash": "28ecfc65853c5bad9a10306375d2484d449ed4bcfe5b7d2f70f95e5a8aaf4730",
"private": false,
"record": {
"abstract": "Repeated black-hole mergers in dense stellar clusters are a plausible mechanism to populate the predicted gap in black hole masses due to the pair-instability process. These hierarchical mergers carry distinct spin and tilt features relative to first-generation black holes, for which previous studies have found evidence at a population level by interpreting features in the effective inspiral spin domain. We introduce an astrophysically-motivated model in the joint space of effective inspiral and precessing spins, which captures the dominant spin dynamics expected for hierarchical mergers. We find decisive evidence both for a population transition above $\\sim 45M_\\odot$, consistent with the anticipated onset of the pair-instability gap, as well as a peak at $\\sim 15 M_\\odot$, which we interpret as the global peak in the hierarchical merger rate. The existence of low- and high-mass subpopulations of higher-generation black holes suggests the contribution of both near-solar-metallicity and metal-poor star clusters to the hierarchical merger population. Our results reinforce the growing evidence for detailed, mass-dependent substructure in the spin distribution of the binary black hole population.",
"arxiv_id": "2601.07908",
"authors": [
"Cailin Plunkett",
"Thomas Callister",
"Michael Zevin",
"Salvatore Vitale"
],
"categories": [
"gr-qc",
"astro-ph.HE"
],
"license": "http://creativecommons.org/licenses/by-nc-sa/4.0/",
"title": "Signatures of a subpopulation of hierarchical mergers in the GWTC-4 gravitational-wave dataset",
"url": "https://arxiv.org/abs/2601.07908",
"version": "v1"
},
"schema_id": "dorsal/arxiv",
"source": {
"execution_id": "19ea427e-8829-4b39-9045-ca2115457d92",
"id": "arXiv Dataset",
"type": "Model",
"variant": "snapshot-2026-01-17",
"version": "0.1.0"
},
"user_id": 1000002
}