{"paper":{"title":"Not All Who Wander Are Lost: Early Excess Demographics in the Volume-limited ZTF DR2 SN Ia Sample","license":"http://creativecommons.org/licenses/by/4.0/","headline":"Early-excess Type Ia supernovae show significantly larger SALT2 stretch and r-band secondary maximum flux than no-excess events.","cross_cats":["astro-ph.CO","astro-ph.GA","astro-ph.SR"],"primary_cat":"astro-ph.HE","authors_text":"Anyu Wang, C\\'esar Rojas-Bravo, Chun Chen, Jifeng Liu, Mathew Smith, Ning-Chen Sun, Xiaohan Chen, Yi-Han Zhao, Zexi Niu, Zi-Yang Wang","submitted_at":"2026-05-14T06:32:51Z","abstract_excerpt":"Early-time flux excesses in Type Ia supernovae (SNe~Ia) offer a unique insight into their progenitor systems and explosion mechanisms. Although individual early-excess events and larger searches have been reported, demographic studies remain limited by sample size. We present a systematic search for early-time excess emission in a volume-limited sample ($z<0.06$) of SNe~Ia based on the Zwicky Transient Facility Data Release 2 (ZTF DR2). Using ZTF $g$- and $r$-band light curves, we identify candidates showing early-excesses shortly after the explosion time, and we apply conservative coverage an"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"Early-excess events have larger SALT2 stretch x1 (7.91σ) and larger r-band secondary-maximum flux Fr2 (6.25σ), while differences in SALT2 color c are weak (0.57σ).","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"The conservative coverage and quality requirements applied to ZTF light curves produce unbiased excess and no-excess catalogs that accurately reflect intrinsic population differences.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Early-excess Type Ia supernovae in the ZTF volume-limited sample have larger SALT2 stretch (7.91 sigma) and r-band secondary maximum flux (6.25 sigma) than no-excess events, with weaker host differences.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Early-excess Type Ia supernovae show significantly larger SALT2 stretch and r-band secondary maximum flux than no-excess events.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"0c23a527264fc8eefe6336af4ec57f18c52780248df910fe831fd19aa0cc3c10"},"source":{"id":"2605.14437","kind":"arxiv","version":1},"verdict":{"id":"834c0e84-c8bc-4245-9bf5-606bbba66853","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-15T01:29:27.843548Z","strongest_claim":"Early-excess events have larger SALT2 stretch x1 (7.91σ) and larger r-band secondary-maximum flux Fr2 (6.25σ), while differences in SALT2 color c are weak (0.57σ).","one_line_summary":"Early-excess Type Ia supernovae in the ZTF volume-limited sample have larger SALT2 stretch (7.91 sigma) and r-band secondary maximum flux (6.25 sigma) than no-excess events, with weaker host differences.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"The conservative coverage and quality requirements applied to ZTF light curves produce unbiased excess and no-excess catalogs that accurately reflect intrinsic population differences.","pith_extraction_headline":"Early-excess Type Ia supernovae show significantly larger SALT2 stretch and r-band secondary maximum flux than no-excess events."},"references":{"count":88,"sample":[{"doi":"","year":2025,"title":"2025, A&A, 694, A3 6","work_id":"1838856d-36e7-441f-a837-f5b1e54fe530","ref_index":1,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2014,"title":"2014, A&A, 568, A22 3","work_id":"fb79093e-7be4-4b2b-81a4-2942f47f0af8","ref_index":2,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2007,"title":"Blondin, S., & Tonry, J. L. 2007, ApJ, 666, 1024 4","work_id":"d39c5acd-7ec8-4a84-8e0a-59c2380da171","ref_index":3,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2021,"title":"2021, ApJ, 909, 26 2","work_id":"49c3089b-a029-4f6b-ae23-9c2722bf697e","ref_index":4,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2022,"title":"2022, ApJ, 938, 110 2","work_id":"108def32-ac25-425d-9296-921e86a7671d","ref_index":5,"cited_arxiv_id":"","is_internal_anchor":false}],"resolved_work":88,"snapshot_sha256":"b97cb4c834503300689c3b63170d5ebce938e39fb30b95332a8d433649d0a4d8","internal_anchors":0},"formal_canon":{"evidence_count":2,"snapshot_sha256":"cdcb380a13dd243bf6355c2f4ccf16510cd2b3bbd143c2b12a8ee85d985f5cdf"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}