{"paper":{"title":"Four-Body Gravitational Microlensing Events Involving Both a Binary Lens and a Binary Source","license":"http://creativecommons.org/licenses/by/4.0/","headline":"Three microlensing events are best fit by four-body models with both binary lenses and binary sources.","cross_cats":[],"primary_cat":"astro-ph.SR","authors_text":"Andrew Gould, Andrzej Udalski, Byeong-Gon Park, Cheongho Han, Chung-Uk Lee, Doeon Kim, Dong-Jin Kim, Dong-Joo Lee, Hongjing Yang, Igor Soszy\\'nski, In-Gu Shin, Jennifer C. Yee, Krzysztof A. Rybicki, Krzysztof Ulaczyk, Kyu-Ha~Hwang, Marcin Wrona, Mariusz Gromadzki, Mateusz J. Mr\\'oz, Michael D. Albrow, Micha{\\l} K. Szyma\\'nskim Jan Skowron, Patryk Iwanek, Pawe{\\l} Pietrukowicz, Przemek Mr\\'oz, Rados{\\l}aw Poleski, Richard W. Pogge, Sang-Mok Cha, Seung-Lee Kim, Sun-Ju Chung, Szymon Koz{\\l}owski, Weicheng Zang, Yongseok Lee, Yoon-Hyun Ryu, Yossi Shvartzvald, Youn Kil Jung","submitted_at":"2026-05-17T21:11:56Z","abstract_excerpt":"We present detailed analyses of three anomalous microlensing events--KMT-2021-BLG-0209, KMT-2021-BLG-0901, and OGLE-2025-BLG-0356--identified from a systematic re-examination of KMTNet light curves for which previous modeling attempts failed or left persistent residuals. Although all three events show caustic-related features consistent with binary-lens microlensing, we find that their full light-curve structures can be described by four-body configurations that required four-body configurations involving a binary lens and a binary source. In KMT-2021-BLG-0209, weak caustic-exit residuals aris"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"The full light-curve structures of KMT-2021-BLG-0209, KMT-2021-BLG-0901, and OGLE-2025-BLG-0356 can be described by four-body configurations involving a binary lens and a binary source, with the 2L2S models providing significantly better fits than 3L1S or 2L1S alternatives.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"That the observed weak caustic-exit residuals, late-time re-brightening, and short isolated anomaly arise specifically from additional caustic interactions with a faint secondary source rather than from unmodeled systematics, higher-order effects, or alternative multi-lens configurations.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Three anomalous microlensing events are re-modeled as binary-lens binary-source (2L2S) systems that resolve prior residuals, with source stars identified as G8V/M3V, G8V/K2V, and G6V/G8V pairs and lenses inferred as low-mass binaries via Bayesian methods.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Three microlensing events are best fit by four-body models with both binary lenses and binary sources.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"27c9bf61a55258a80702eef31f1d8f9c23cabad39743b6715450f0ea483dedba"},"source":{"id":"2605.17654","kind":"arxiv","version":1},"verdict":{"id":"ba8422fd-3ca7-43fc-a4dd-ea1702580c5d","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-19T22:06:27.320086Z","strongest_claim":"The full light-curve structures of KMT-2021-BLG-0209, KMT-2021-BLG-0901, and OGLE-2025-BLG-0356 can be described by four-body configurations involving a binary lens and a binary source, with the 2L2S models providing significantly better fits than 3L1S or 2L1S alternatives.","one_line_summary":"Three anomalous microlensing events are re-modeled as binary-lens binary-source (2L2S) systems that resolve prior residuals, with source stars identified as G8V/M3V, G8V/K2V, and G6V/G8V pairs and lenses inferred as low-mass binaries via Bayesian methods.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"That the observed weak caustic-exit residuals, late-time re-brightening, and short isolated anomaly arise specifically from additional caustic interactions with a faint secondary source rather than from unmodeled systematics, higher-order effects, or alternative multi-lens configurations.","pith_extraction_headline":"Three microlensing events are best fit by four-body models with both binary lenses and binary sources."},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2605.17654/integrity.json","findings":[],"available":true,"detectors_run":[{"name":"doi_title_agreement","ran_at":"2026-05-19T22:31:19.493948Z","status":"completed","version":"1.0.0","findings_count":0},{"name":"cited_work_retraction","ran_at":"2026-05-19T22:22:35.433330Z","status":"completed","version":"1.0.0","findings_count":0},{"name":"doi_compliance","ran_at":"2026-05-19T22:12:14.772944Z","status":"completed","version":"1.0.0","findings_count":0},{"name":"citation_quote_validity","ran_at":"2026-05-19T21:49:44.274364Z","status":"skipped","version":"0.1.0","findings_count":0},{"name":"ai_meta_artifact","ran_at":"2026-05-19T21:33:23.544833Z","status":"skipped","version":"1.0.0","findings_count":0},{"name":"claim_evidence","ran_at":"2026-05-19T21:21:57.462981Z","status":"completed","version":"1.0.0","findings_count":0}],"snapshot_sha256":"020ecc348ea12e6820dadc82220296907bafedfe43eca476030bbb8a886bad95"},"references":{"count":29,"sample":[{"doi":"10.1086/305984","year":1998,"title":"Alard, C., & Lupton, R. H. 1998, ApJ, 503, 325, doi: 10.1086/305984","work_id":"18008e0f-aee1-4b56-873b-f91734f5a862","ref_index":1,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1111/j.1365-2966.2009.15098.x","year":2009,"title":"2010, MNRAS, 401, 2318, doi: 10.1111/j.1365-2966.2009.15845.x","work_id":"23562d5d-936a-4b08-a6f0-15466b0fcd7c","ref_index":2,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1038/365621a0","year":1993,"title":"Alcock, C., Akerlof, C. W., Allsman, R. A., et al. 1993, Nature, 365, 621, doi: 10.1038/365621a0","work_id":"39fbeab3-1161-4bdd-b784-78f4adb55102","ref_index":3,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1038/365623a0","year":1993,"title":"1993, Nature, 365, 623, doi: 10.1038/365623a0","work_id":"022972ca-e114-4b9f-9279-81f9b3226f46","ref_index":4,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1051/0004-6361/201220678","year":2013,"title":"C., Feltzing, S., et al","work_id":"05c40df3-1cdc-489f-bb4d-e2ce3a932018","ref_index":5,"cited_arxiv_id":"","is_internal_anchor":false}],"resolved_work":29,"snapshot_sha256":"a8e5055222dadb3b12210511934e01bf522fe68a0fcca1031e8e7d9628adac4b","internal_anchors":4},"formal_canon":{"evidence_count":2,"snapshot_sha256":"b943209187b26f64f98990a1fb14c75e148dce752ae76ce2b9a66459e2b1680c"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}