{
  "abstract": "Supernova remnants (SNRs) are widely considered to be the primary accelerators of Galactic cosmic rays. In recent years, detailed observations have significantly progressed for young SNRs interacting with molecular clouds, a prime example being RX J1713.7-3946. When molecular clouds are clumpy, their impact can affect not only radiation properties but also shock wave propagation. Therefore, a quantitative understanding linking observational quantities with the ambient medium structure is highly required. In this study, we perform three-dimensional hydrodynamic simulations to model a molecular cloud with an inhomogeneous density structure driven by supersonic turbulence and subsequent SNR formation. To investigate various pre-supernova environments, we systematically vary the medium clumpiness by replacing gas below a threshold number density with a low-density hot gas, quantifying the relationship between the forward shock velocity and the volume filling factor of the high-density clumps. As a result, we find that at an elapsed time of 1000 yr-a typical age for a young SNR-the forward shock can evolve consistently with the fast shock velocity measured in RX J1713.7-3946, provided that the clump volume filling factor is approximately 10% or less. Considering that hadronic gamma-ray emission originates exclusively from the clumpy, high-density gas, our findings suggest that the total energy of cosmic-ray protons in RX J1713.7-3946 is higher than previously estimated, amounting to at least a few percent of the typical supernova explosion energy.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.17477",
  "author_total": 2,
  "authors": [
    {
      "name": "Kenta Tatsumi"
    },
    {
      "name": "Tsuyoshi Inoue"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7k0xn8544fq72.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.17477",
  "fulltext_url": null,
  "id": "7k0xn8544fq72",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.17477",
  "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": "W7203784780",
  "pdf_url": "https://arxiv.org/pdf/2608.17477",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-16",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7k0xn8544fq72.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:01Z",
      "native_id": "2608.17477",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.17477"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "Impact of Upstream Clumpiness on Supernova Remnant Forward Shock Evolution in Molecular Cloud Environments",
  "title_text": "Impact of Upstream Clumpiness on Supernova Remnant Forward Shock Evolution in Molecular Cloud Environments",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:01Z",
  "url": "https://research.draconitic.com/paper/7k0xn8544fq72",
  "venue": "arXiv",
  "versions": []
}