{
  "abstract": "Galactic cosmic rays (GCRs) are thought to originate from shock acceleration in supernova remnants, but interstellar ionization rates suggest an additional low-energy cosmic-ray (LECR) component. LECRs excite nuclei in the ISM, producing MeV gamma-ray line emission through subsequent de-excitation. Observations of this emission can constrain the LECR flux, morphology, and acceleration mechanisms. We construct all-sky maps of Galactic de-excitation emission using three-dimensional (3D) CR distribution models. By comparing them with the Galactic diffuse gamma-ray emission, we assess the detectability of the de-excitation line components against the underlying continuum. We calculate the emission by combining 3D CR distributions from GALPROP and gamma-ray production cross sections from TALYS. We also model an additional LECR component motivated by the high ionization rates measured in the ISM. The predicted de-excitation emission is relatively weak when integrated over the broad regions commonly adopted in MeV gamma-ray analyses ($|l|\\leq30^{\\circ}$ and $|b|\\leq15^{\\circ}$), contributing only $\\lesssim 1\\%$ above the leptonic continuum even considering the additional LECR component. The all-sky maps reveal that, in the standard scenario, the de-excitation-to-leptonic flux ratio remains low over the entire sky, reaching at most ${\\sim}20\\%$ toward the Galactic anticenter. In contrast, models including an additional LECR component exhibit a pronounced enhancement toward the GC, where the ratio exceeds $100\\%$, indicating favourable prospects for detection through spatially resolved analyses. The 6.1-to-4.4 MeV intensity ratio is particularly sensitive to the maximum energy of the injected LECR spectrum, varying by up to ${\\sim} 30\\%$. Future MeV gamma-ray observatories could thus identify a distinct LECR population and constrain its acceleration and transport.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.23380",
  "author_total": 11,
  "authors": [
    {
      "name": "Tomohiko Oka"
    },
    {
      "name": "Thomas Siegert"
    },
    {
      "name": "Tristan Bouchet"
    },
    {
      "name": "Laura Eisenberger"
    },
    {
      "name": "Mika A. Gelowicz"
    },
    {
      "name": "Saurabh Mittal"
    },
    {
      "name": "Rudi Reinhardt"
    },
    {
      "name": "Manuel R. H. W. Skalka"
    },
    {
      "name": "Dimitris Tsatsis"
    },
    {
      "name": "Hiroki Yoneda"
    },
    {
      "name": "Manja Zimmerer"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/0vaf2njbfg907.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.23380",
  "fulltext_url": null,
  "id": "0vaf2njbfg907",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.23380",
  "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",
      "astro-ph.HE"
    ],
    [
      "openalex",
      "3106|Astrophysics and Cosmic Phenomena"
    ]
  ],
  "openalex": "W7222915050",
  "pdf_url": "https://arxiv.org/pdf/2610.23380",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-16",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/0vaf2njbfg907.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:30:32Z",
      "native_id": "2610.23380",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.23380"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "Three-dimensional spatial modelling of nuclear de-excitation lines",
  "title_text": "Three-dimensional spatial modelling of nuclear de-excitation lines",
  "type": "preprint",
  "updated_at": "2026-10-30T12:33:28Z",
  "url": "https://research.draconitic.com/paper/0vaf2njbfg907",
  "venue": "arXiv",
  "versions": []
}