{"paper":{"title":"Pristine Massive Star Formation Caught at the Break of Cosmic Dawn","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.CO","authors_text":"Massimo Stiavelli, Pietro Bergamini, Takahiro Morishita, Tommaso Treu, Yechi Zhang, Zhaoran Liu","submitted_at":"2025-07-14T17:47:04Z","abstract_excerpt":"The existence of galaxies with no heavy elements is a key prediction of cosmological models. So far no \"zero-metallicity\", or Population~III, galaxies have been identified. Here, we report the identification of an extremely metal-poor galaxy AMORE6 at redshift $z=5.7253$, multiply imaged by a foreground galaxy cluster. JWST spectra consistently detect ${\\rm H\\beta}$ at both positions, but [OIII]$_{\\lambda\\lambda4960,5008}$ remains undetected. This places a firm upper limit on its oxygen abundance, $<$0.19% of solar metallicity at 3$\\sigma$, establishing itself as the most pristine galaxy by fa"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2507.10521","kind":"arxiv","version":3},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2507.10521/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"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"}