{"paper":{"title":"Ultracompact Anisotropic Stars and Gravastars in General Relativity","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":[],"primary_cat":"gr-qc","authors_text":"Nora Bret\\'on, Prajwal Hassan Puttasiddappa, Santiago Esteban Perez Bergliaffa","submitted_at":"2026-08-11T14:45:09Z","abstract_excerpt":"We study static, spherically symmetric ultracompact objects in General Relativity with anisotropic stress. Using the covariant anisotropic equation of state and assuming homogeneous density, we construct a mostly analytical model admitting configurations beyond the Buchdahl limit and with compactness arbitrarily close to the black hole value. The solutions exhibit two regimes separated by a critical curve in the parameter space of compactness and anisotropy, associated with the divergence of the central pressure: regular anisotropic configurations with positive central pressure, and singular c"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2608.10991","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2608.10991/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}