{"paper":{"title":"Maximal mass of neutron stars constrained by neutron star observations","license":"http://creativecommons.org/licenses/by/4.0/","headline":"Neutron star observations constrain the maximum mass to 2.2-2.3 solar masses with weak dependence on the baseline equation of state.","cross_cats":["hep-ph","nucl-th"],"primary_cat":"astro-ph.HE","authors_text":"G\\'abor Kasza, Gy\\\"orgy Wolf","submitted_at":"2026-05-01T06:13:01Z","abstract_excerpt":"We investigate constraints on the high-density equation of state (EOS) of neutron star matter by analyzing the probability distributions of the endpoints of mass-radius M(R) sequences within a Bayesian weighting framework. Starting from two representative hadronic baseline EOSs, SFHo and DD2, matched at higher densities to an extended linear sigma model description and constrained to approach perturbative QCD (pQCD) results, we construct families of causal hybrid EOSs spanning a broad range of stiffness at supranuclear densities. Observational constraints from the binary neutron-star merger GW"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"We find that the maximum-mass distributions are largely determined by observational constraints and show only weak sensitivity to the choice of baseline EOS, favoring values around 2.2-2.3 M⊙ when the most robust constraints are applied.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"That the constructed families of causal hybrid EOSs, obtained by matching baseline hadronic models to an extended linear sigma model and enforcing pQCD asymptotics, adequately span the physically allowed high-density behavior without missing important phase transitions or other degrees of freedom.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Bayesian analysis of causal hybrid EOS models constrained by neutron-star observations favors a maximum mass of 2.2-2.3 solar masses with radius near 12 km, largely independent of the hadronic baseline.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Neutron star observations constrain the maximum mass to 2.2-2.3 solar masses with weak dependence on the baseline equation of state.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"4050bdaeb0f90cf7b0426d074c942ecaf0fd5e558085f046a10b9f3d32bd33e8"},"source":{"id":"2605.00437","kind":"arxiv","version":2},"verdict":{"id":"18d448dc-7df0-4f3d-87b7-ffd51d0363c7","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-09T19:13:39.546774Z","strongest_claim":"We find that the maximum-mass distributions are largely determined by observational constraints and show only weak sensitivity to the choice of baseline EOS, favoring values around 2.2-2.3 M⊙ when the most robust constraints are applied.","one_line_summary":"Bayesian analysis of causal hybrid EOS models constrained by neutron-star observations favors a maximum mass of 2.2-2.3 solar masses with radius near 12 km, largely independent of the hadronic baseline.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"That the constructed families of causal hybrid EOSs, obtained by matching baseline hadronic models to an extended linear sigma model and enforcing pQCD asymptotics, adequately span the physically allowed high-density behavior without missing important phase transitions or other degrees of freedom.","pith_extraction_headline":"Neutron star observations constrain the maximum mass to 2.2-2.3 solar masses with weak dependence on the baseline equation of state."},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2605.00437/integrity.json","findings":[],"available":true,"detectors_run":[{"name":"ai_meta_artifact","ran_at":"2026-05-20T19:42:48.648803Z","status":"completed","version":"1.0.0","findings_count":0},{"name":"doi_compliance","ran_at":"2026-05-19T18:10:22.250183Z","status":"completed","version":"1.0.0","findings_count":0}],"snapshot_sha256":"26f3dd3c76c28042f075b80be50f9b0ad95cdd08f3267041673955811f84a81b"},"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"}