{
  "abstract": "Elastic photon--dark matter scattering attenuates gamma-ray spectra along a line of sight, probing the same operators as dark matter annihilation to photons but at a rate linear, rather than quadratic, in dark matter density. We consider Standard Model gauge-invariant effective operators of mass-dimension 5 to 7, suppressed by a cutoff scale $Λ$, coupling scalar, Majorana or Dirac dark matter to the photon. The leading operators with non-vanishing real-photon amplitudes enter at dimension-5 for Dirac dark matter and dimension-7 for Majorana dark matter. In the electroweak-doublet dipole portal, the inelastic splitting invoked to evade direct detection also closes the CMB annihilation bound, leaving attenuation the only one of the three photon-sector probes that survives. Applying this to a pixel-level reanalysis of 17 years of \\textit{Fermi}--LAT Pass~8 data toward the Galactic centre, we derive the first operator-resolved sensitivity estimates for photon--dark matter scattering from the Galactic halo: $Λ\\simeq 0.32~\\mathrm{GeV}$ for the dimension-5 Dirac dipoles, $0.21~\\mathrm{GeV}$ for the dimension-6 scalar Rayleigh operator and $0.79$--$1.06~\\mathrm{GeV}$ for the dimension-7 Rayleigh family. The reach is weak: it lies below the EFT-validity threshold across the cold dark matter mass range, and is superseded on the dipole plane by CMB and direct-detection constraints. The framework is calibrated against pseudo-experiments, and recomputes the sensitivity for any instrument that provides a per-bin spectrum with uncertainties and a line-of-sight column density.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.29546",
  "author_total": 6,
  "authors": [
    {
      "name": "Trinity Rosebud Stenhouse"
    },
    {
      "name": "Asli Acar"
    },
    {
      "name": "Mikhail Bashkanov"
    },
    {
      "name": "Frank F. Deppisch"
    },
    {
      "name": "Chamkaur Ghag"
    },
    {
      "name": "Dan P. Watts"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/70d5szt4dn1e3.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.29546",
  "fulltext_url": null,
  "id": "70d5szt4dn1e3",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.29546",
  "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"
    ],
    [
      "arxiv",
      "hep-ex"
    ],
    [
      "openalex",
      "3106|Dark Matter and Cosmic Phenomena"
    ]
  ],
  "openalex": "W7204910619",
  "pdf_url": "https://arxiv.org/pdf/2608.29546",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-30",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/70d5szt4dn1e3.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:41Z",
      "native_id": "2608.29546",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.29546"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-ex",
      "subfield": "high-energy"
    }
  ],
  "title": "Photon--Dark Matter Elastic Scattering: An Effective-Operator Scan and First Operator-Resolved Sensitivity Estimates from the Galactic Halo",
  "title_text": "Photon--Dark Matter Elastic Scattering: An Effective-Operator Scan and First Operator-Resolved Sensitivity Estimates from the Galactic Halo",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:41Z",
  "url": "https://research.draconitic.com/paper/70d5szt4dn1e3",
  "venue": "arXiv",
  "versions": []
}