Ionizing Photon Production Efficiencies and Chemical Abundances at Cosmic Dawn Revealed by Ultra-Deep Rest-Frame Optical Spectroscopy of JADES-GS-z14-0

2025/12/22 by Jakob M. Helton, Helton, Jakob M., Jane E. Morrison +83
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena

paper · doi:10.48550/arxiv.2512.19695

openalex publication_date 2025/12/22 · openalex created_date 2025/12/24 · openalex updated_date 2026/07/28

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. This spectrum covers the brightest rest-frame optical nebular emission lines for the luminous galaxy JADES-GS-z14-0 at z > 14. Most notably, we detect [OIII] λλ4959,5007 at ≈ 11 σ and Hα at ≈ 4 σ with these ultra-deep observations. These lines reveal that JADES-GS-z14-0 has low dust attenuation with a recent star-formation rate of SFR ≈ 10 ± 2 M_\odot / yr, star-formation rate surface density of Σ_SFR ≈ 23 ± 5 M_\odot/yr/kpc², and ionizing photon production efficiency of ξ_ion ≈ 10^{25.3 ± 0.1} Hz/erg. Using standard strong-line diagnostics, we infer a gas-phase oxygen abundance of [O/H] ≈ -1.1 ± 0.4 (≈ 10% Z_\odot), carbon-to-oxygen ratio of [C/O] ≈ -0.4 ± 0.4, ionization parameter of log₁₀(U) \gtrsim -2.4, and density of n_H ≈ 720 ± 210 cm^-3. Using detailed photoionization modeling, we instead derive [O/H] ≈ -0.3_-0.4^+0.4 (≈ 50% Z_\odot) and log₁₀(U) ≈ -1.5_-0.4^+0.3. 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. 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. [Abridged]

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Related

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