{
  "abstract": "We introduce a spectral-model-independent spectral-shape metric, $δ_{\\rm rms}$, to probe phase-resolved spectral evolution in the Galactic ultraluminous X-ray pulsar Swift J0243.6+6124. The $δ_{\\rm rms}$--luminosity relation reveals a reproducible convergence--redivergence behavior: spectra from two geometrically opposite pulse phases converge to near identity around $L_{\\rm t}^{\\ast}\\sim8.8\\times10^{37}\\ \\mathrm{erg\\ s^{-1}}$, with a mean shape difference of only $\\sim2\\%$, and rediverge at higher luminosities, most prominently at higher energies. This strong phase-resolved spectral convergence coincides with a pulse-profile reversal and traces the same transition luminosities previously identified from broadband continuum evolution, including $L_{\\rm t}\\sim4.5\\times10^{37}\\ \\mathrm{erg\\ s^{-1}}$. These results suggest a possible luminosity-driven reweighting between a broadly distributed surface-reprocessed/reflected component and an increasingly important direct accretion-column contribution, while establishing $δ_{\\rm rms}$ as a robust, spectral-model-independent diagnostic of radiation-geometry restructuring in bright accreting X-ray pulsars.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: ApJ, 1008, 216 (2026)",
  "arxiv": "2610.38232",
  "author_total": 12,
  "authors": [
    {
      "name": "Bo-Yan Chen"
    },
    {
      "name": "Peng-Ju Wang"
    },
    {
      "name": "Shu Zhang"
    },
    {
      "name": "Ling-Da Kong"
    },
    {
      "name": "Long Ji"
    },
    {
      "name": "Shuang-Nan Zhang"
    },
    {
      "name": "Hua Feng"
    },
    {
      "name": "Yu-Peng Chen"
    },
    {
      "name": "Ming-Yu Ge"
    },
    {
      "name": "Jing-Qiang Peng"
    },
    {
      "name": "Qing-Cang Shui"
    },
    {
      "name": "Wen-Zhong Li"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7jyc2e5asdcsm.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.38232",
  "fulltext_url": null,
  "id": "7jyc2e5asdcsm",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.38232",
  "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.HE"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2610.38232",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-28",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7jyc2e5asdcsm.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:36:23Z",
      "native_id": "2610.38232",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.38232"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "A Spectral-model-independent Diagnostic of Phase-resolved Spectral Convergence in Swift J0243.6+6124",
  "title_text": "A Spectral-model-independent Diagnostic of Phase-resolved Spectral Convergence in Swift J0243.6+6124",
  "type": "preprint",
  "updated_at": "2026-11-01T12:20:44Z",
  "url": "https://research.draconitic.com/paper/7jyc2e5asdcsm",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.3847/1538-4357/ae8db8",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}