{
  "abstract": "Detecting quadratic quasi-normal modes in black hole ringdowns would provide evidence for nonlinear gravitational dynamics, while measuring their properties would enable tests of the corresponding predictions of general relativity. Specifically, second-order black hole perturbation theory predicts that their amplitudes scale with the product of the amplitudes of their parent linear modes, with a coupling coefficient that depends on the spin of the remnant black hole. This mode-specific coupling coefficient has not yet been directly measured from gravitational wave data. Here, we use Bayesian inference on the GW250114 ringdown, modeled with the $220$, $221$, and $220\\times220$ modes, to infer the amplitude-coupling coefficient of the $220\\times220$ mode. The inferred coefficient is consistent with predictions from numerical relativity fits and second-order perturbation theory; no comparison shows a deviation exceeding $1.3 σ$. Although the current data cannot distinguish among these spin-dependent predictions, this measurement establishes a basis for more stringent observational tests of nonlinear gravitational dynamics in black-hole ringdowns.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.28953",
  "author_total": 3,
  "authors": [
    {
      "name": "Yuxin Yang"
    },
    {
      "name": "Changfu Shi"
    },
    {
      "name": "Yi-Ming Hu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/djeg2bk2gbx4k.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.28953",
  "fulltext_url": null,
  "id": "djeg2bk2gbx4k",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.28953",
  "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": "W7214389975",
  "pdf_url": "https://arxiv.org/pdf/2609.28953",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-24",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/djeg2bk2gbx4k.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:24:11Z",
      "native_id": "2609.28953",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.28953"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    }
  ],
  "title": "Constraining the Quadratic-mode Amplitude Coupling in GW250114",
  "title_text": "Constraining the Quadratic-mode Amplitude Coupling in GW250114",
  "type": "preprint",
  "updated_at": "2026-10-30T12:24:11Z",
  "url": "https://research.draconitic.com/paper/djeg2bk2gbx4k",
  "venue": "arXiv",
  "versions": []
}