{
  "abstract": "Magnetar giant flares are thought to eject $\\gtrsim 10^{-9}\\,M_\\odot$ of baryons, as inferred from the radio afterglow of the 2004 flare of SGR 1806-20. One proposed mechanism is a shock driven into the neutron-star crust by the hot, high-pressure layer that the flare creates above the surface. The unbound crust could undergo $r$-process nucleosynthesis and power a short-lived \"nova brevis\". We study this crust ejection with general-relativistic neutrino-radiation hydrodynamics simulations performed with AthenaK, using a tabulated nuclear equation of state and two-moment neutrino transport, for flare pressures corresponding to magnetic fields $B = 10^{15}$-$10^{16.5}$ G, and compute the nucleosynthesis of the ejecta with a nuclear reaction network. We find that such flares unbind $10^{-10}$ to $5\\times10^{-8}\\,M_\\odot$ of crust. The ejecta keep the electron fraction of the crust to within a few hundredths, and weak interactions affect it mainly in the most energetic flares. The fast, high-entropy ejecta freeze out mostly as $α$ particles and free neutrons. In the stronger flares nuclei up to the third $r$-process peak do form, but those with $A \\geq 90$ make up at most $\\approx 8\\times10^{-4}$ of the ejected mass, or $\\approx 3.5\\times10^{-11}\\,M_\\odot$ per flare, and less than $10^{-5}$ for $B \\leq 10^{15.5}$ G. A nova brevis from these ejecta would be powered mainly by the decay of free neutrons. Like earlier work, our models assume spherical symmetry, a flare that covers the whole star, and no magnetic field. A field tangential to the surface would hold the crust down and weaken the shock, and a flare confined to part of the surface should eject proportionally less mass. We therefore regard our ejecta masses as upper limits for a given flare pressure, and expect realistic magnetar flares to produce negligible amounts of $r$-process material.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2611.07022",
  "author_total": 4,
  "authors": [
    {
      "name": "Tetyana Pitik"
    },
    {
      "name": "David Radice"
    },
    {
      "name": "Jacob Fields"
    },
    {
      "name": "Yi Qiu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bv79y1tqnzamb.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2611.07022",
  "fulltext_url": null,
  "id": "bv79y1tqnzamb",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2611.07022",
  "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"
    ],
    [
      "arxiv",
      "nucl-th"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2611.07022",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-04",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bv79y1tqnzamb.ris",
  "sources": [
    {
      "first_seen": "2026-11-06T18:21:30Z",
      "native_id": "2611.07022",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2611.07022"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "physics",
      "origin": "arxiv:nucl-th",
      "subfield": "nuclear"
    }
  ],
  "title": "General-relativistic neutrino-radiation hydrodynamics of crust ejection in magnetar giant flares",
  "title_text": "General-relativistic neutrino-radiation hydrodynamics of crust ejection in magnetar giant flares",
  "type": "preprint",
  "updated_at": "2026-11-09T00:20:39Z",
  "url": "https://research.draconitic.com/paper/bv79y1tqnzamb",
  "venue": "arXiv",
  "versions": []
}