{
  "abstract": "GW231123 is a gravitational-wave signal originating from the merger of a black hole binary with total mass $\\sim\\!250\\, {\\rm M}_{\\odot }$, the largest ever detected by the LIGO–Virgo–Kagra Collaboration. Remarkably, under standard priors, the system features among the fastest spinning binary components confidently measured in binary mergers, $\\chi _{1,2} \\gtrsim 0.7$ at $90{{\\, \\rm per\\, cent}}$ one-dimensional credibility, according to the most accurate model employed. As typical binary mergers result in remnants with $\\chi \\sim 0.7$, such spin values are challenging to obtain even from previous (hierarchical) mergers. These inferred properties rely on waveform models lacking eccentric corrections in the merger-ringdown stage. Here, we show that binaries retaining significant eccentricity up to merger can be misinterpreted as near-extremally spinning when non-circular corrections are neglected. Binary-agnostic ringdown analysis instead provides unbiased estimates of the remnant properties, provided that a robust estimate of the signal peak can be obtained. We re-analyse GW231123 using available eccentric numerical-relativity catalogues, finding that although eccentric templates can provide a good fit to the data, quasi-spherical templates are still favoured. Ringdown analyses confirm a secondary likelihood peak correlated with large eccentricity values, but improved eccentric models will be required to assess the reliability of this interpretation. Finally, analysing GW231123 under population-informed parametric priors confirms the exceptional nature of this event within the current black hole binary population.",
  "abstract_shown": true,
  "affiliations": [
    "Max Planck Institute for Gravitational Physics (Albert Einstein Institute) , Am Mühlenberg 1, D-14476 Potsdam ,",
    "Institute for Gravitation & the Cosmos, Department of Physics, Penn State University , University Park, PA 16802 ,",
    "Indian Institute of Technology , Bombay, Mumbai-400076 ,",
    "Gran Sasso Science Institute (GSSI) , I-67100 L’Aquila ,",
    "INFN, Laboratori Nazionali del Gran Sasso , I-67100 Assergi ,",
    "School of Physics and Astronomy and Institute for Gravitational Wave Astronomy, University of Birmingham , Edgbaston, Birmingham B15 2TT ,"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 4,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Koustav Chandra",
      "orcid": "0000-0003-4750-5551"
    },
    {
      "affs": [
        2
      ],
      "name": "Johann Fernandes"
    },
    {
      "affs": [
        3,
        4
      ],
      "name": "Akshita Mittal"
    },
    {
      "affs": [
        5
      ],
      "name": "Gregorio Carullo",
      "orcid": "0000-0001-9090-1862"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7gex9a4ecsvs0.bib",
  "cited_by": 0,
  "doi": "10.1093/mnras/stag1934",
  "fulltext_url": null,
  "id": "7gex9a4ecsvs0",
  "issns": [
    "0035-8711",
    "1365-2966"
  ],
  "landing_url": "https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1934/8910744",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3103|Pulsars and Gravitational Waves Research"
    ]
  ],
  "openalex": "W7164880066",
  "pdf_url": "https://academic.oup.com/mnras/advance-article-pdf/doi/10.1093/mnras/stag1934/71881030/stag1934.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-12",
  "publisher": "Oxford University Press (OUP)",
  "ris": "https://research.draconitic.com/paper/7gex9a4ecsvs0.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:17Z",
      "native_id": "10.1093/mnras/stag1934",
      "source": "crossref",
      "url": "https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1934/8910744"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Pulsars and Gravitational Waves Research",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "Eccentricity in disguise? Insights from GW231123 and numerically simulated binary black hole merger signals",
  "title_text": "Eccentricity in disguise? Insights from GW231123 and numerically simulated binary black hole merger signals",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:17Z",
  "url": "https://research.draconitic.com/paper/7gex9a4ecsvs0",
  "venue": "Monthly Notices of the Royal Astronomical Society",
  "versions": [
    {
      "doi": "10.48550/arxiv.2606.15150",
      "pid": "3xhdjjdvvahjd",
      "relation": "preprint",
      "title": "Eccentricity in Disguise? Insights from GW231123 and Numerically Simulated Binary Black Hole Merger Signals",
      "venue": "arXiv"
    }
  ]
}