{"paper":{"title":"The long-term evolution of Ultra Faint Dwarf Galaxies and observational implications","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"Simulations of ultra-faint dwarf galaxies without dark matter show that binary stars can substantially overestimate their velocity dispersions.","cross_cats":[],"primary_cat":"astro-ph.GA","authors_text":"Alessandro Alberto Trani, Francesco Flammini Dotti, Giovanni Carraro, Rainer Spurzem, Roberto Capuzzo-Dolcetta","submitted_at":"2026-01-19T13:39:45Z","abstract_excerpt":"Context. In the Local Group, dwarf spheroidal galaxies (dSphs) and ultra-faint dwarf galaxies (UFDs) exhibit large velocity dispersions. These values are generally attributed to the presence of substantial amounts of dark matter (DM), in line with the predictions of the standard model of galaxy formation. However, alternative, more conservative explanations exist, such as non-virialized dynamical states induced by tidal interactions, the presence of stellar streams, and artificial inflation of the velocity dispersion caused by binary-star orbital motion. Aims. We study the dynamical evolution "},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"if not taken into account properly, velocity dispersion measurements can be strongly biased by the presence of a significant binary population, which can lead to substantial overestimates of velocity dispersion in UFDs","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"That the chosen initial conditions, binary fractions, and purely stellar (no dark matter) setup accurately represent real ultra-faint dwarf galaxies and that the N-body code captures all relevant physics over a Hubble time.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"N-body simulations of ultra-faint dwarf galaxies without dark matter find a 3-billion-year quasi-stationary phase followed by mass segregation, with binaries causing substantial overestimates of velocity dispersion.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Simulations of ultra-faint dwarf galaxies without dark matter show that binary stars can substantially overestimate their velocity dispersions.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"4ac1b289fe54aab6adc895268b73fe7a8fb59c42d32f0dd79d106b751f2082ce"},"source":{"id":"2601.13049","kind":"arxiv","version":2},"verdict":{"id":"7f385a1d-aece-4ba5-a704-24f3c1333a04","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-16T13:36:35.683148Z","strongest_claim":"if not taken into account properly, velocity dispersion measurements can be strongly biased by the presence of a significant binary population, which can lead to substantial overestimates of velocity dispersion in UFDs","one_line_summary":"N-body simulations of ultra-faint dwarf galaxies without dark matter find a 3-billion-year quasi-stationary phase followed by mass segregation, with binaries causing substantial overestimates of velocity dispersion.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"That the chosen initial conditions, binary fractions, and purely stellar (no dark matter) setup accurately represent real ultra-faint dwarf galaxies and that the N-body code captures all relevant physics over a Hubble time.","pith_extraction_headline":"Simulations of ultra-faint dwarf galaxies without dark matter show that binary stars can substantially overestimate their velocity dispersions."},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2601.13049/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":45,"sample":[{"doi":"","year":1988,"title":"Aaronson, M. & Olszewski, E. 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W., et al. 2007, ApJ, 654, 897","work_id":"030799b4-4778-4bec-ba3e-77cce04ca158","ref_index":5,"cited_arxiv_id":"","is_internal_anchor":false}],"resolved_work":45,"snapshot_sha256":"b548355c1540c3cd2b306d40b03f79bc30c63789a3897f30c6b173b002f32b31","internal_anchors":0},"formal_canon":{"evidence_count":2,"snapshot_sha256":"1eec8875684a43d2ce32165ef2b28bf762890b347d5382a129f467e969e238d4"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}