{
  "abstract": "We study scalar and electromagnetic perturbations of the root--Kerr object. Its source-free exterior carries the electromagnetic field obtained in the vanishing-mass limit of the Kerr--Newman black hole, while its physical source is a rotating disk with an essential distributional rim contribution. For a massless charged scalar, the minimally coupled Klein--Gordon equation separates into a confluent-Heun (CHE) radial equation with a direct coupling between the scalar and background charges. We give the associated Nekrasov--Shatashvili (NS) dictionary and show that the disk is an ordinary radial point. For electromagnetic pertubations, we derive the equations for the radiative Newman--Penrose Maxwell scalars directly. They have the same confluent-Heun structure, but a Maxwell perturbation has no bulk coupling to the background potential. Charge-dependent photon scattering data therefore cannot be fixed by the exterior equation alone. We formulate the disk/rim boundary-data problem, identify the response data required to convert exact CHE/NS connection coefficients into a physical scattering matrix, and show how all-spin helicity-flip Compton information constrains the response on the radiative subspace. The analysis separates exact exterior propagation and amplitude matching from the additional source dynamics required for a microscopic response.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.09191",
  "author_total": 1,
  "authors": [
    {
      "name": "Samim Akhtar"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/2ccraf8hncxj9.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.09191",
  "fulltext_url": null,
  "id": "2ccraf8hncxj9",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.09191",
  "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",
      "gr-qc"
    ],
    [
      "arxiv",
      "hep-th"
    ],
    [
      "openalex",
      "3106|Black Holes and Theoretical Physics"
    ]
  ],
  "openalex": "W7212150053",
  "pdf_url": "https://arxiv.org/pdf/2609.09191",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/2ccraf8hncxj9.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:12Z",
      "native_id": "2609.09191",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.09191"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-th",
      "subfield": "high-energy"
    }
  ],
  "title": "On scalar and electromagnetic perturbations of the root--Kerr object",
  "title_text": "On scalar and electromagnetic perturbations of the root--Kerr object",
  "type": "preprint",
  "updated_at": "2026-10-30T12:20:12Z",
  "url": "https://research.draconitic.com/paper/2ccraf8hncxj9",
  "venue": "arXiv",
  "versions": []
}