Astrophysical viability of extremal black holes

[2512.01898] Astrophysical viability of extremal black holes Skip to main content Search Submit Donate Log in Search arXiv Press Enter to search · Advanced search General Relativity and Quantum Cosmology arXiv:2512.01898 (gr-qc) [Submitted on 1 Dec 2025 ( v1 ), last revised 14 Aug 2026 (this version, v2)] Title: Astrophysical viability of extremal black holes Authors: Chiara Coviello , Ruth Gregory View a PDF of the paper titled Astrophysical viability of extremal black holes, by Chiara Coviello and Ruth Gregory View PDF HTML (experimental) Abstract: We take a fresh look at the viability of physically realistic extremal black holes within our (non-supersymmetric) low energy physics. By incorporating prefactors and volume effects, we show that Schwinger discharge in charge neutral environments is far more efficient than commonly assumed. Using ionisation estimates for neutral hydrogen, we obtain a new and robust lower bound on the mass of an extremal electrically charged black hole, exceeding $10^{14} M_\odot$. For magnetic black holes, we compute the Lee-Nair-Weinberg instability and revisit early universe pair creation rates, including singular instantons that substantially enhance production, to demonstrate that the extreme charges required for stability are cosmologically implausible. Finally, we speculate that an extremal Kerr black hole could shed angular momentum via superradiant scattering from the stochastic gravitational wave background. Taken together, our results provide a unified picture that extremal black holes are unlikely to persist in our universe. Comments: 19 pages, 5 figures Subjects: General Relativity and Quantum Cosmology (gr-qc) ; Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th) Cite as: arXiv:2512.01898 [gr-qc] (or arXiv:2512.01898v2 [gr-qc] for this version) https://doi.org/10.48550/arXiv.2512.01898 Focus to learn more arXiv-issued DOI via DataCite Journal reference: Class. Quantum Grav. (2026) 43, 157002 Related DOI : https://doi.org/10.1088/1361-6382/ae94d4 Focus to learn more DOI(s) linking to related resources Submission history From: Chiara Coviello [ view email ] [v1] Mon, 1 Dec 2025 17:19:12 UTC (49 KB) [v2] Fri, 14 Aug 2026 18:14:48 UTC (333 KB) Full-text links: Access Paper: View a PDF of the paper titled Astrophysical viability of extremal black holes, by Chiara Coviello and Ruth Gregory View PDF HTML (experimental) TeX Source view license Current browse context: gr-qc < prev | next > new | recent | 2025-12 Change to browse by: astro-ph astro-ph.CO hep-th References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loading... Data provided by: Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer ( What is the Explorer? ) Connected Papers Toggle Connected Papers ( What is Connected Papers? ) Litmaps Toggle Litmaps ( What is Litmaps? ) scite.ai Toggle scite Smart Citations ( What are Smart Citations? ) Code, Data, Media Code, Data and Media Associated with this Article alphaXiv Toggle alphaXiv ( What is alphaXiv? ) Links to Code Toggle CatalyzeX Code Finder for Papers ( What is CatalyzeX? ) DagsHub Toggle DagsHub ( What is DagsHub? ) GotitPub Toggle Gotit.pub ( What is GotitPub? ) Huggingface Toggle Hugging Face ( What is Huggingface? ) ScienceCast Toggle ScienceCast ( What is ScienceCast? ) Demos Demos Replicate Toggle Replicate ( What is Replicate? ) Spaces Toggle Hugging Face Spaces ( What is Spaces? ) Spaces Toggle TXYZ.AI ( What is TXYZ.AI? ) Related Papers Recommenders and Search Tools Link to Influence Flower Influence Flower ( What are Influence Flowers? ) Core recommender toggle CORE Recommender ( What is CORE? ) IArxiv recommender toggle IArxiv Recommender ( What is IArxiv? ) Author Venue Institution Topic About arXivLabs arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them. Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs . Which authors of this paper are endorsers? | Disable MathJax ( What is MathJax? ) We gratefully acknowledge support from our major funders , member institutions , , and all contributors. About · Help · Contact · Subscribe · Copyright · Privacy · Accessibility · Operational Status (opens in new tab) Major funding support from

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