{
  "abstract": "In General Relativity, axial and polar black-hole perturbations share identical quasinormal-mode spectra, a property known as isospectrality. New physics can break this degeneracy, producing a spectral splitting analogous to atomic fine structure. We perform a theory-agnostic search for such splitting in gravitational-wave observations. We find no evidence for isospectrality breaking and place a combined $90\\%$ upper limit of $<28.5\\%$ on the relative frequency splitting. We map these constraints onto several modified-gravity theories, constraining the coupling-lengths to be $\\lesssim 28\\,\\mathrm{km}$.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.18989",
  "author_total": 4,
  "authors": [
    {
      "name": "Adrian Ka-Wai Chung"
    },
    {
      "name": "Richard Dyer"
    },
    {
      "name": "Tomasz Kinowski"
    },
    {
      "name": "Christopher J. Moore"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3a3m0x1jvkztd.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.18989",
  "fulltext_url": null,
  "id": "3a3m0x1jvkztd",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.18989",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.HE"
    ],
    [
      "arxiv",
      "gr-qc"
    ],
    [
      "openalex",
      "3103|Pulsars and Gravitational Waves Research"
    ]
  ],
  "openalex": "W7222294619",
  "pdf_url": "https://arxiv.org/pdf/2610.18989",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-13",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3a3m0x1jvkztd.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:31Z",
      "native_id": "2610.18989",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.18989"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    }
  ],
  "title": "Black Hole Fine Structure",
  "title_text": "Black Hole Fine Structure",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:31Z",
  "url": "https://research.draconitic.com/paper/3a3m0x1jvkztd",
  "venue": "arXiv",
  "versions": []
}