{"paper":{"title":"Sub-GeV dark matter in neutron stars: halo morphologies and their suppression by vacuum-like pressure","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"A percent-level vacuum-like dark energy admixture markedly reduces dark matter halo sizes around neutron stars.","cross_cats":["hep-ph"],"primary_cat":"astro-ph.HE","authors_text":"Germ\\'an Lugones, Jos\\'e Ademir S. Lima, Loreany F. Ara\\'ujo","submitted_at":"2025-11-09T18:25:18Z","abstract_excerpt":"We investigate neutron stars that contain a unified dark sector composed of cold, degenerate fermionic dark matter and a vacuum-like dark-energy component. Within a general-relativistic two-fluid framework that allows a covariantly conserved, gradient-driven energy exchange between baryons and the dark sector, we quantify how dark microphysics reshapes global structure when the total gravitational radius need not coincide with the luminous baryonic radius. Using a state-of-the-art baryonic equation of state, we explore the halo-forming mass range for fermionic dark matter with particle masses "},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"Our central new result is that a percent-level vacuum-like admixture markedly reduces halo formation, shrinking the radius difference from several kilometers to sub-kilometer scales and the fractional mass difference to ≲1%.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"The assumption that a covariantly conserved, gradient-driven energy exchange exists between baryons and the dark sector, together with the specific functional form chosen for the vacuum-like pressure term.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"A small vacuum-like dark-energy admixture in neutron stars with 400 MeV–1 GeV fermionic dark matter shrinks halo-induced radius differences from several kilometers to sub-kilometer scales and mass differences to ≲1%.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"A percent-level vacuum-like dark energy admixture markedly reduces dark matter halo sizes around neutron stars.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"9e4d77614a81a03b0ab0e603b2dc8f4b3d451139974725c4ed484e5fc5215175"},"source":{"id":"2511.06489","kind":"arxiv","version":2},"verdict":{"id":"0f55be7d-733f-43a9-b46d-a478c84ec452","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-17T23:22:31.867905Z","strongest_claim":"Our central new result is that a percent-level vacuum-like admixture markedly reduces halo formation, shrinking the radius difference from several kilometers to sub-kilometer scales and the fractional mass difference to ≲1%.","one_line_summary":"A small vacuum-like dark-energy admixture in neutron stars with 400 MeV–1 GeV fermionic dark matter shrinks halo-induced radius differences from several kilometers to sub-kilometer scales and mass differences to ≲1%.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"The assumption that a covariantly conserved, gradient-driven energy exchange exists between baryons and the dark sector, together with the specific functional form chosen for the vacuum-like pressure term.","pith_extraction_headline":"A percent-level vacuum-like dark energy admixture markedly reduces dark matter halo sizes around neutron stars."},"references":{"count":38,"sample":[{"doi":"","year":2005,"title":"Particle Dark Matter: Evidence, Candidates and Constraints","work_id":"9f1f415a-e524-408a-8b8d-07c41bbab6c3","ref_index":1,"cited_arxiv_id":"hep-ph/0404175","is_internal_anchor":true},{"doi":"","year":2019,"title":"Direct Detection of WIMP Dark Mat- ter: Concepts and Status","work_id":"a244886a-6cf5-46c6-915a-ca59e747e134","ref_index":2,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2018,"title":"A new era in the search for dark matter","work_id":"15ac97d4-0471-46f3-b750-2c6f6d1c781d","ref_index":3,"cited_arxiv_id":"1810.01668","is_internal_anchor":true},{"doi":"","year":2014,"title":"On the capture of dark matter by neutron stars","work_id":"0aea2b86-d413-412c-a209-d1d8c09e00b8","ref_index":4,"cited_arxiv_id":"1201.2400","is_internal_anchor":true},{"doi":"","year":1989,"title":"I. Goldman and S. Nussinov,Weakly interacting massive particles and neutron stars,Phys. Rev. D40(1989) 3221","work_id":"1d5d0d39-da2f-4eb4-b0b2-acff74b35cb5","ref_index":5,"cited_arxiv_id":"","is_internal_anchor":false}],"resolved_work":38,"snapshot_sha256":"600b1bbcbf6fda8df4ebfa95ecb7048a145965d5bac6bf6f750dd6b6d0aa2819","internal_anchors":18},"formal_canon":{"evidence_count":2,"snapshot_sha256":"7d78fb9edf1fda92e602c4d6e204fdbdb3aa9bac15c994243927a730e58d8378"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}