{
  "abstract": "Context. LHAASO~J2108+5157 is one of the most intriguing Galactic ultra-high-energy $γ$-ray sources. It is detected up to hundreds of TeV but lacks a clear counterpart at lower frequencies. Fermi-LAT observations have revealed a compact GeV source spatially coincident with the PeV emission, while VERITAS and LST-1 impose stringent upper limits in the intermediate TeV band, producing a pronounced spectral suppression between the GeV and TeV domains. Aims. We investigate a time-dependent hadronic scenario in which a past episode of microquasar jet activity injected relativistic protons that are now observed in a relic phase. Methods. Energy-dependent diffusion naturally segregates the particle population: Lower-energy protons remain confined near dense molecular gas and account for the GeV emission, whereas higher-energy particles reach more distant material, producing the hard TeV--PeV component. Results. For representative interstellar conditions, the model is simultaneously consistent with the broadband spectral energy distribution, the spatial compact--extended dichotomy, and the lack of detectable radio or X-ray counterparts. Conclusions. The observed bimodal $γ$-ray phenomenology thus emerges as a transport effect of a single injected proton population, supporting the interpretation of LHAASO~J2108+5157 as a fossil microquasar remnant observed at an intermediate evolutionary stage and highlighting relic jet systems as a viable class of Galactic PeVatrons.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.18353",
  "author_total": 7,
  "authors": [
    {
      "name": "Josep Mart\\'ı"
    },
    {
      "name": "Pedro L. Luque-Escamilla"
    },
    {
      "name": "Leandro Abaroa"
    },
    {
      "name": "Gustavo E. Romero"
    },
    {
      "name": "Valent\\'ı Bosch-Ramon"
    },
    {
      "name": "Josep M. Paredes"
    },
    {
      "name": "Cintia S. Peri"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/avqdf8cpt3aan.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.18353",
  "fulltext_url": null,
  "id": "avqdf8cpt3aan",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.18353",
  "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"
    ],
    [
      "openalex",
      "3106|Astrophysics and Cosmic Phenomena"
    ]
  ],
  "openalex": "W7213493499",
  "pdf_url": "https://arxiv.org/pdf/2609.18353",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-16",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/avqdf8cpt3aan.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:01Z",
      "native_id": "2609.18353",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.18353"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "The unidentified PeV source LHAASO J2108+5157: A microquasar remnant?",
  "title_text": "The unidentified PeV source LHAASO J2108+5157: A microquasar remnant?",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:01Z",
  "url": "https://research.draconitic.com/paper/avqdf8cpt3aan",
  "venue": "arXiv",
  "versions": []
}