{ "abstract": "JWST has discovered an early period of galaxy formation that was more vigorous than expected, which has challenged our understanding of the early Universe. In this work, we present the longest spectroscopic integration ever acquired by JWST/MIRI ( t obs ≈ 51 hr). This spectrum covers the brightest rest-frame optical nebular emission lines for the luminous galaxy JADES-GS-z14-0 at z = 14.18. Most notably, we detect [O III ] λλ 4959, 5007 at ≈14 σ and H α at ≈4 σ with these ultradeep observations. These lines reveal that JADES-GS-z14-0 has low dust attenuation with a recent star formation rate of SFR ≈ 8 ± 2 M ⊙ yr −1 , star formation rate surface density of Σ SFR ≈ 20 ± 5 M ⊙ yr −1 kpc −2 , and ionizing photon production efficiency of ξ ion ≈ 10 25.3±0.1 Hz erg −1 . Using standard strong-line diagnostics, we infer a gas-phase oxygen abundance of log 10 ( O / H ) + 12 ≈ 7.5 ± 0.2 (≈6% Z ⊙ ), carbon-to-oxygen ratio of [C/O] ≈ −0.4 ± 0.2, ionization parameter of log 10 ( U ) ≳ − 2.4 , and density of n H ≈ 690 ± 200 cm −3 . Using detailed photoionization modeling, we instead derive log 10 ( O / H ) + 12 ≈ 8 . 5 − 0.4 + 0.4 (≈60% Z ⊙ ), log 10 ( U ) ≈ − 1 . 4 − 0.4 + 0.3 , and n H ≈ 54 0 − 320 + 520 cm − 3 . The inferred properties of JADES-GS-z14-0 are similar to those measured for similarly luminous galaxies at z > 10 with previous MIRI/Spectroscopy, such as GHZ2/GLASSz12, GN-z11, and MACS0647-JD1. These results suggest extreme ionization conditions and rapid metal enrichment less than 300 Myr after the Big Bang. Existing simulations are unable to reproduce the empirical and inferred properties of JADES-GS-z14-0. This work demonstrates an important step toward understanding the formation of the first stars and heavy elements in the Universe. Future work will focus on the detection of the rest-frame optical continuum and its interpretation for the stellar population properties of JADES-GS-z14-0.", "abstract_shown": true, "affiliations": [ "The Pennsylvania State University", "University of Arizona", "University of Cambridge", "Space Telescope Science Institute", "Scuola Normale Superiore", "Northwestern University", "Center for Astrophysics ∣ Harvard and Smithsonian", "University of Copenhagen", "University of Oxford", "Sorbonne Université", "European Southern Observatory", "University of Hertfordshire", "Cosmic Dawn Center (DAWN)", "Tsinghua University", "University College London", "University of Wisconsin-Madison", "Centro de Astrobiología (CAB)", "University of California", "Max-Planck-Institut für extraterrestrische Physik (MPE)", "NSF National Optical-Infrared Astronomy Research Laboratory", "NRC Herzberg" ], "article_type": null, "arxiv": null, "author_total": 43, "authors": [ { "affs": [ 0 ], "name": "Jakob M. Helton", "orcid": "0000-0003-4337-6211" }, { "affs": [ 1 ], "name": "Jane E. Morrison", "orcid": "0000-0002-9288-9235" }, { "affs": [ 1 ], "name": "Kevin Hainline", "orcid": "0000-0003-4565-8239" }, { "affs": [ 2 ], "name": "Francesco D’Eugenio", "orcid": "0000-0003-2388-8172" }, { "affs": [ 1 ], "name": "George H. Rieke", "orcid": "0000-0003-2303-6519" }, { "affs": [ 3 ], "name": "Stacey L. Alberts", "orcid": "0000-0002-8909-8782" }, { "affs": [ 4 ], "name": "Stefano Carniani", "orcid": "0000-0002-6719-380X" }, { "affs": [ 0 ], "name": "Joel Leja", "orcid": "0000-0001-6755-1315" }, { "affs": [ 5 ], "name": "Yijia Li", "orcid": "0000-0002-0682-3310" }, { "affs": [ 3 ], "name": "Pierluigi Rinaldi", "orcid": "0000-0002-5104-8245" }, { "affs": [ 2 ], "name": "Jan Scholtz", "orcid": "0000-0001-6010-6809" }, { "affs": [ 1 ], "name": "Meredith A. Stone", "orcid": "0000-0002-9720-3255" }, { "affs": [ 1 ], "name": "Christopher N. A. Willmer", "orcid": "0000-0001-9262-9997" }, { "affs": [ 6 ], "name": "Zihao Wu", "orcid": "0000-0002-8876-5248" }, { "affs": [ 7 ], "name": "William M. Baker", "orcid": "0000-0003-0215-1104" }, { "affs": [ 8 ], "name": "Andrew J. Bunker", "orcid": "0000-0002-8651-9879" }, { "affs": [ 9 ], "name": "S. Charlot", "orcid": "0000-0003-3458-2275" }, { "affs": [ 8 ], "name": "Jacopo Chevallard", "orcid": "0000-0002-7636-0534" }, { "affs": [ 0 ], "name": "Nikko J. Cleri", "orcid": "0000-0001-7151-009X" }, { "affs": [ 10 ], "name": "Mirko Curti", "orcid": "0000-0002-2678-2560" }, { "affs": [ 11 ], "name": "Emma Curtis-Lake", "orcid": "0000-0002-9551-0534" }, { "affs": [ 1 ], "name": "Eiichi Egami", "orcid": "0000-0003-1344-9475" }, { "affs": [ 6 ], "name": "Daniel J. Eisenstein", "orcid": "0000-0002-2929-3121" }, { "affs": [ 12, 7 ], "name": "P. Jakobsen", "orcid": "0000-0002-6780-2441" }, { "affs": [ 1 ], "name": "Zhiyuan Ji", "orcid": "0000-0001-7673-2257" }, { "affs": [ 6 ], "name": "Benjamin D. Johnson", "orcid": "0000-0002-9280-7594" }, { "affs": [ 3 ], "name": "Nimisha Kumari", "orcid": "0000-0002-5320-2568" }, { "affs": [ 13 ], "name": "Xiaojing Lin", "orcid": "0000-0001-6052-4234" }, { "affs": [ 1 ], "name": "Jianwei Lyu", "orcid": "0000-0002-6221-1829" }, { "affs": [ 14, 2 ], "name": "R. Maiolino", "orcid": "0000-0002-4985-3819" }, { "affs": [ 15 ], "name": "Michael V. Maseda", "orcid": "0000-0003-0695-4414" }, { "affs": [ 16 ], "name": "Pablo G. Pérez‐González", "orcid": "0000-0003-4528-5639" }, { "affs": [ 1 ], "name": "Marcia J. Rieke", "orcid": "0000-0002-7893-6170" }, { "affs": [ 17 ], "name": "Brant E. Robertson", "orcid": "0000-0002-4271-0364" }, { "affs": [ 14, 8 ], "name": "Aayush Saxena", "orcid": "0000-0001-5333-9970" }, { "affs": [ 6 ], "name": "Fengwu Sun", "orcid": "0000-0002-4622-6617" }, { "affs": [ 2 ], "name": "Sandro Tacchella", "orcid": "0000-0002-8224-4505" }, { "affs": [ 18 ], "name": "Hannah Übler", "orcid": "0000-0003-4891-0794" }, { "affs": [ 4 ], "name": "Giacomo Venturi", "orcid": "0000-0001-8349-3055" }, { "affs": [ 19 ], "name": "Christina C. Williams", "orcid": "0000-0003-2919-7495" }, { "affs": [ 20 ], "name": "Chris J. Willott", "orcid": "0000-0002-4201-7367" }, { "affs": [ 12, 7 ], "name": "Joris Witstok", "orcid": "0000-0002-7595-121X" }, { "affs": [ 1 ], "name": "Yongda Zhu", "orcid": "0000-0003-3307-7525" } ], "bibtex": "https://research.draconitic.com/paper/8rga75srg4fm3.bib", "cited_by": 21, "doi": "10.3847/2041-8213/ae7446", "fulltext_url": null, "id": "8rga75srg4fm3", "issns": [ "2041-8205", "2041-8213" ], "landing_url": "https://hal.science/hal-05760819v1", "language": "en", "licence": "CC-BY-NC-ND-4.0", "licence_label": "CC BY-NC-ND 4.0", "licence_source": "article", "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/", "metadata_licence": null, "native_subjects": [ [ "hal", "0.phys" ], [ "hal", "1.phys.astr" ], [ "hal", "2.phys.astr.co" ], [ "openalex", "3103|Galaxies: Formation, Evolution, Phenomena" ] ], "openalex": "W7164831357", "pdf_url": "https://hal.science/hal-05760819/document", "pmcid": null, "pmid": null, "published": "2026-06-15", "publisher": "Bristol : IOP Publishing", "ris": "https://research.draconitic.com/paper/8rga75srg4fm3.ris", "sources": [ { "first_seen": "2026-10-30T12:17:43Z", "native_id": "hal-05760819", "source": "hal", "url": "https://hal.science/hal-05760819v1" }, { "first_seen": "2026-11-07T13:20:45Z", "native_id": "W7164831357", "source": "openalex", "url": "https://doi.org/10.3847/2041-8213/ae7446" } ], "subjects": [ { "field": "astronomy", "origin": "hal:2.phys.astr.co", "subfield": "cosmology" }, { "field": "physics", "origin": "hal:0.phys", "subfield": "general" } ], "title": "Ionizing Photon Production Efficiencies and Chemical Abundances at Cosmic Dawn Revealed by Ultradeep Rest-frame Optical Spectroscopy of JADES-GS-z14-0", "title_text": "Ionizing Photon Production Efficiencies and Chemical Abundances at Cosmic Dawn Revealed by Ultradeep Rest-frame Optical Spectroscopy of JADES-GS-z14-0", "type": "peer-reviewed", "updated_at": "2026-11-09T13:21:02Z", "url": "https://research.draconitic.com/paper/8rga75srg4fm3", "venue": "The Astrophysical Journal Letters", "versions": [] }