{
  "abstract": "Soft X-ray flashes (XRFs) are predicted from a variety of hypothesized phenomena, including \"dirty fireballs\" (relativistic jets with significant baryon loading), and gamma-ray bursts viewed marginally off-axis. For a given burst, detailed multiwavelength observations are necessary for distinguishing between possible progenitor scenarios, but the number of XRFs with such data remains small. Here we present X-ray, optical, and radio (mm to cm) data of GRB 250419A, an XRF (with peak energy $E_p<4\\,$keV) discovered by the Space-based multi-band astronomical Variable Objects Monitor. We observe a clear achromatic break in the X-ray and optical bands, and likely two spectral components in the radio emission. The afterglow is similar to the long-duration gamma-ray burst population, but slightly underluminous, and the optical afterglow has an unusually shallow decay phase at $\\lesssim2\\,$d. We find that the event is well explained by a high-Lorentz factor jet with low kinetic energy ($E\\sim10^{49}$-$10^{50}\\,$erg), with energy injection that could arise from radial stratification and/or the jet being viewed marginally off-axis. We conclude that at least some X-ray flashes are an extension of classical gamma-ray bursts down to lower energies.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.00508",
  "author_total": 27,
  "authors": [
    {
      "name": "Genevieve Schroeder"
    },
    {
      "name": "Anna Y.Q Ho"
    },
    {
      "name": "Gavin P Lamb"
    },
    {
      "name": "Tanmoy Laskar"
    },
    {
      "name": "Daniel A Perley"
    },
    {
      "name": "Ore Gottlieb"
    },
    {
      "name": "Tomas Ahumada"
    },
    {
      "name": "Igor Andreoni"
    },
    {
      "name": "Aleksandra Bochenek"
    },
    {
      "name": "Michael Bremer"
    },
    {
      "name": "Michael Camilo"
    },
    {
      "name": "Jonathan Carney"
    },
    {
      "name": "S. Bradley Cenko"
    },
    {
      "name": "Alessandra Corsi"
    },
    {
      "name": "Michael W Coughlin"
    },
    {
      "name": "James Freeburn"
    },
    {
      "name": "Erica Hammerstein"
    },
    {
      "name": "Rahul Jayaraman"
    },
    {
      "name": "Mansi M Kasliwal"
    },
    {
      "name": "Noel Klingler"
    },
    {
      "name": "Brendan O'Connor"
    },
    {
      "name": "Cassie Sevilla"
    },
    {
      "name": "Gokul P Srinivasaragavan"
    },
    {
      "name": "Robert Stein"
    },
    {
      "name": "Jada L Vail"
    },
    {
      "name": "Sylvain Veilleux"
    },
    {
      "name": "Lin Yan"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7r16mdrcbqfqt.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.00508",
  "fulltext_url": null,
  "id": "7r16mdrcbqfqt",
  "issns": [],
  "landing_url": "https://hal.science/hal-05842235v1",
  "language": "en",
  "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"
    ],
    [
      "hal",
      "0.phys"
    ],
    [
      "hal",
      "1.phys.astr"
    ],
    [
      "openalex",
      "3103|Gamma-ray bursts and supernovae"
    ]
  ],
  "openalex": "W7216221813",
  "pdf_url": "https://arxiv.org/pdf/2610.00508",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7r16mdrcbqfqt.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:02Z",
      "native_id": "hal-05842235",
      "source": "hal",
      "url": "https://hal.science/hal-05842235v1"
    },
    {
      "first_seen": "2026-10-30T12:26:03Z",
      "native_id": "2610.00508",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.00508"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "physics",
      "origin": "hal:0.phys",
      "subfield": "general"
    }
  ],
  "title": "X-ray Through Radio Observations and Modeling of the Soft X-ray Flash GRB 250419A",
  "title_text": "X-ray Through Radio Observations and Modeling of the Soft X-ray Flash GRB 250419A",
  "type": "preprint",
  "updated_at": "2026-10-30T12:26:03Z",
  "url": "https://research.draconitic.com/paper/7r16mdrcbqfqt",
  "venue": "HAL",
  "versions": []
}