{
  "abstract": "We study single-particle Penrose extraction from a rotating black hole whose mass decreases in time, described by the ingoing Kerr-Vaidya metric, imposing exact four-momentum conservation at the decay. We prove that the local efficiency is bounded by the instantaneous Kerr value, through a covariant bound that reduces to the Bardeen-Press-Teukolsky limit at the horizon, and we derive an exact transport law, dE/dtau = -dm/dt (r/Sigma) p_r^2 for fixed spin parameter, by which every timelike geodesic gains energy while the hole loses mass. The net energy gain therefore splits into a local Penrose term and two transport terms, which we compute numerically as functions of spin and mass-loss rate for two mass-loss laws. With fixed spin parameter, extraction is possible only below a critical rate alpha_crit(a) = (M-a)/Delta v, set by the approach of the hole to extremality; with fixed a/m no such boundary exists. The transport law extends to the Kerr-Newman-Vaidya family, and the regime where the dynamics matter is shown to lie far outside astrophysical mass-loss rates.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.19175",
  "author_total": 1,
  "authors": [
    {
      "name": "Fabio Buffoli"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7ydjj0kg6ge0b.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.19175",
  "fulltext_url": null,
  "id": "7ydjj0kg6ge0b",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.19175",
  "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"
    ],
    [
      "arxiv",
      "gr-qc"
    ],
    [
      "openalex",
      "3106|Black Holes and Theoretical Physics"
    ]
  ],
  "openalex": "W7213578141",
  "pdf_url": "https://arxiv.org/pdf/2609.19175",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-20",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7ydjj0kg6ge0b.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:04Z",
      "native_id": "2609.19175",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.19175"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    }
  ],
  "title": "Penrose process in radiating Kerr-Vaidya black holes: efficiency, energy transport, and the viability boundary",
  "title_text": "Penrose process in radiating Kerr-Vaidya black holes: efficiency, energy transport, and the viability boundary",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:04Z",
  "url": "https://research.draconitic.com/paper/7ydjj0kg6ge0b",
  "venue": "arXiv",
  "versions": []
}