{
  "abstract": "The ultraviolet continuum from a high-redshift accreting black hole is routinely used to infer its mass. GN-z11 offers a sharp test of whether that inference is secure. A thin-disk fit to its continuum gives an Eddington mass of $M_{\\rm E}=1.12\\times10^{7}\\,\\Msun$, an order of magnitude above the $\\log(\\Mbh/\\Msun)=6.2\\pm0.3$ inferred from broad N~\\textsc{iv}. We show that this apparent tension is not imposed by the ultraviolet slope alone. We derive a closed-form criterion comparing the radius where observed photons are produced with the radius where a supercritical flow departs from efficient solution. For GN-z11, the criterion places the supercritical transition inside the ultraviolet-emitting region. Composite disks retaining the outer solution confirm this numerically, requiring $\\Mdot_{\\rm out}=3.1$--$4.4\\,\\Msun\\,\\mathrm{yr^{-1}}$ and placing $\\Rsph=(1.2$--$1.8)\\times10^{3}\\,\\rg$ inside $\\Ruv=(2.6$--$2.9)\\times10^{3}\\,\\rg$. Replacing the inner $\\sim10^{3}\\rg$ by a supercritical flow shifts the fitted slope by only $Δ\\betaUV=+0.08$ to $+0.11$, comparable to uncertainties from standard spectral modelling. Reversing the radial ordering requires the effective transition to move outward by a factor $1.7$--$2.1$. Within our composite models, the measured slope constrains black-hole mass only to around $10^{6}\\,\\Msun$, an order of magnitude below the continuum Eddington mass. Continuum Eddington masses should therefore be treated as model-dependent bounds that assume global thin-disk efficiency. The same hierarchy appears in three additional JWST sources under the disk-dominated interpretation, where separation masses are only $4$--$6$\\% of continuum Eddington masses. This distinction can substantially weaken the seed-mass and early-growth demands inferred from ultraviolet continua at cosmic dawn for the first massive black holes.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.15967",
  "author_total": 2,
  "authors": [
    {
      "name": "Samik Mitra"
    },
    {
      "name": "Ramananda Santra"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/007aacfvx0980.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.15967",
  "fulltext_url": null,
  "id": "007aacfvx0980",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.15967",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.CO"
    ],
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "arxiv",
      "astro-ph.HE"
    ],
    [
      "openalex",
      "3103|Astrophysical Phenomena and Observations"
    ]
  ],
  "openalex": "W7213279115",
  "pdf_url": "https://arxiv.org/pdf/2609.15967",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-14",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/007aacfvx0980.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:21:25Z",
      "native_id": "2609.15967",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.15967"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "A Standard Ultraviolet Continuum Can Hide Supercritical Accretion in GN-z11",
  "title_text": "A Standard Ultraviolet Continuum Can Hide Supercritical Accretion in GN-z11",
  "type": "preprint",
  "updated_at": "2026-10-30T12:21:25Z",
  "url": "https://research.draconitic.com/paper/007aacfvx0980",
  "venue": "arXiv",
  "versions": []
}