{
  "abstract": "To overcome the failure of the conventional non-relativistic description of statistics in strong gravitational fields, we develop a covariant theory for a photon gas in curved spacetime, starting from the Boltzmann equation and employing the relaxation time approximation. The transport coefficients are computed up to second order, which are not a massless limit of the massive-particle results due to the fundamentally different phase-space geometry of null particles. At second order, the gravitational field renders the coefficients tensor-valued and induces transverse fluxes, analogous to the Hall effect. Using the first-order results, we derive relativistic generalizations of Fick's and Fourier's laws and obtain the radiation diffusion equation for spherically symmetric accretion disks. This provides a covariant description of radiative transport in strong gravitational fields for high-energy astrophysical applications.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.02615",
  "author_total": 3,
  "authors": [
    {
      "name": "Jianan Wang"
    },
    {
      "name": "Long Cui"
    },
    {
      "name": "Bin Wu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/76wjmpqaqecz9.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.02615",
  "fulltext_url": null,
  "id": "76wjmpqaqecz9",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.02615",
  "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",
      "gr-qc"
    ],
    [
      "arxiv",
      "hep-th"
    ],
    [
      "openalex",
      "3103|Astrophysical Phenomena and Observations"
    ]
  ],
  "openalex": "W7207767874",
  "pdf_url": "https://arxiv.org/pdf/2609.02615",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-02",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/76wjmpqaqecz9.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:16Z",
      "native_id": "2609.02615",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.02615"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-th",
      "subfield": "high-energy"
    }
  ],
  "title": "Covariant linear response theory for a photon gas in curved spacetime",
  "title_text": "Covariant linear response theory for a photon gas in curved spacetime",
  "type": "preprint",
  "updated_at": "2026-10-30T12:18:16Z",
  "url": "https://research.draconitic.com/paper/76wjmpqaqecz9",
  "venue": "arXiv",
  "versions": []
}