{
  "abstract": "We report 10 epochs of 22 GHz East Asia To Italy: Nearly Global VLBI (EATING VLBI) observations of the nearby radio galaxy 3C~111 obtained from 2020 to 2023. Combined with VLBA data at 15 and 43 GHz, these observations yield a 64-epoch, multi-frequency sequence of high-resolution radio images. We used high-resolution Bayesian Stokes~I imaging and Gaussian component modeling to derive light curves and knot kinematics. We find evidence that a faster, later-emitted knot catches up with a slower, earlier knot at a deprojected distance of about 10 pc from the central engine. The knot component responsible for this interaction propagated at relativistic speed and exhibited a rise-and-decay evolution over approximately six months. The Stokes~I flux evolution supports the internal shock interpretation, while archival polarization images reveal a temporary increase in fractional linear polarization in the interaction region near the Stokes~I flux maximum. The timing of the 2021 GeV flare suggests that this earlier high-energy event is more naturally associated with activity near the core. These results provide direct evidence for an internal shock in an active galactic nucleus jet and support a hybrid picture in which internal and standing shocks coexist in relativistic jets and may play different roles in their variability.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.23410",
  "author_total": 24,
  "authors": [
    {
      "name": "Kenzo Kawamura"
    },
    {
      "name": "Motoki Kino"
    },
    {
      "name": "Mareki Honma"
    },
    {
      "name": "Kazuhiro Hada"
    },
    {
      "name": "Paul Tiede"
    },
    {
      "name": "Evgeniya Kravchenko"
    },
    {
      "name": "Marcello Giroletti"
    },
    {
      "name": "Rocco Lico"
    },
    {
      "name": "Kazunori Akiyama"
    },
    {
      "name": "Mieko Takamura"
    },
    {
      "name": "Filippo D'Ammando"
    },
    {
      "name": "Monica Orienti"
    },
    {
      "name": "Gabriele Giovannini"
    },
    {
      "name": "Fumie Tazaki"
    },
    {
      "name": "Bong Won Sohn"
    },
    {
      "name": "Salvatore Buttaccio"
    },
    {
      "name": "Lang Cui"
    },
    {
      "name": "Giuseppe Maccaferri"
    },
    {
      "name": "Andrea Melis"
    },
    {
      "name": "Alexey Melnikov"
    },
    {
      "name": "Carlo Migoni"
    },
    {
      "name": "Matteo Stagni"
    },
    {
      "name": "Kiyoaki Wajima"
    },
    {
      "name": "Takeshi Sakai"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/6cpqr7c4204hw.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.23410",
  "fulltext_url": null,
  "id": "6cpqr7c4204hw",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.23410",
  "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.GA"
    ],
    [
      "arxiv",
      "astro-ph.HE"
    ],
    [
      "openalex",
      "3103|Astrophysical Phenomena and Observations"
    ]
  ],
  "openalex": "W7214023950",
  "pdf_url": "https://arxiv.org/pdf/2609.23410",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-20",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/6cpqr7c4204hw.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:19Z",
      "native_id": "2609.23410",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.23410"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "Observational Evidence of an Internal Shock Collision in the Relativistic Jet of the Nearby Radio Galaxy 3C 111",
  "title_text": "Observational Evidence of an Internal Shock Collision in the Relativistic Jet of the Nearby Radio Galaxy 3C 111",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:19Z",
  "url": "https://research.draconitic.com/paper/6cpqr7c4204hw",
  "venue": "arXiv",
  "versions": []
}