{
  "abstract": "Understanding the astrophysical origins of binary black holes requires accurate and flexible modeling of multidimensional population properties. In this Letter, using a data-driven framework based on binned Gaussian processes, we characterize the joint distribution of BBH primary masses, mass ratios, and effective inspiral spins. We identify three distinct subpopulations in the GWTC-4 sample of observations and investigate their astrophysical origins. We find that only one of the three subpopulations exhibits the 35 M ⊙ peak, which is characterized by a strong preference for equal mass systems and isotropic spin orientations. Our inferred distributions are consistent with a predominantly dynamical origin of this feature. By comparing with theoretical simulations, we further show that the subpopulation that exhibits the 35 M ⊙ peak can exclusively comprise dynamically assembled systems in globular clusters, specifically if black hole birth spins are in the range (0.1−0.2), whereas the other two subpopulations require substantial contributions from alternative formation channels. We constrain the lower bound on the merger rate of BBHs in globular clusters to be 0.6 9 − 0.33 + 0.23 Gpc − 3 yr − 1 , which is consistent with most theoretical predictions (that can range from 0.2 to 57 Gpc −3 yr −1 depending on modeling assumptions). We conclude that dynamical formation in globular clusters remains a strong candidate for the origin of this excess near 30−40 M ⊙ and that more data and targeted parametric models are necessary to rigorously establish this interpretation.",
  "abstract_shown": true,
  "affiliations": [
    "Northwestern University",
    "NSF-Simons AI Institute for the Sky (SkAI)"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 3,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Omkar Sridhar",
      "orcid": "0009-0008-3375-1077"
    },
    {
      "affs": [
        1,
        0
      ],
      "name": "Anarya Ray",
      "orcid": "0000-0002-7322-4748"
    },
    {
      "affs": [
        1,
        0
      ],
      "name": "Vicky Kalogera",
      "orcid": "0000-0001-9236-5469"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/4etka7bqvdrfz.bib",
  "cited_by": 22,
  "doi": "10.3847/2041-8213/ae8011",
  "fulltext_url": null,
  "id": "4etka7bqvdrfz",
  "issns": [
    "2041-8205",
    "2041-8213"
  ],
  "landing_url": "https://doi.org/10.3847/2041-8213/ae8011",
  "language": "en",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3103|Pulsars and Gravitational Waves Research"
    ]
  ],
  "openalex": "W4416942814",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-07-03",
  "publisher": "IOP Publishing",
  "ris": "https://research.draconitic.com/paper/4etka7bqvdrfz.ris",
  "sources": [
    {
      "first_seen": "2026-11-07T13:20:45Z",
      "native_id": "W4416942814",
      "source": "openalex",
      "url": "https://doi.org/10.3847/2041-8213/ae8011"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Pulsars and Gravitational Waves Research",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "Characterizing Binary Black Hole Subpopulations in GWTC-4 with Binned Gaussian Processes: On the Origins of the 35 M ⊙ Peak",
  "title_text": "Characterizing Binary Black Hole Subpopulations in GWTC-4 with Binned Gaussian Processes: On the Origins of the 35 M ⊙ Peak",
  "type": "peer-reviewed",
  "updated_at": "2026-11-09T13:21:02Z",
  "url": "https://research.draconitic.com/paper/4etka7bqvdrfz",
  "venue": "The Astrophysical Journal Letters",
  "versions": []
}