JADES-GS-z14-1: A Compact, Faint Galaxy at <i>z</i> ≈ 14 with Weak Metal Lines from Extremely Deep JWST MIRI, NIRCam, and NIRSpec Observations
Abstract JWST has shed light on galaxy formation and metal enrichment within 300 Myr of the Big Bang. While luminous galaxies at z > 10 often show significant [O iii ] λλ 4959, 5007 emission lines, it remains unclear whether such features are prevalent among fainter, more typical galaxies due to observational limits. We present deep imaging and spectroscopy of JADES-GS-z14-1 at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>z</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">spec</mml:mi> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>13.8</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>6</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.05</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.04</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> , currently the faintest spectroscopically confirmed galaxy at z ≈ 14. It serendipitously received 70.7 hr of MIRI/F770W imaging in the JWST Advanced Deep Extragalactic Survey (JADES), the deepest MIRI exposure for any high-redshift galaxy to date. Nonetheless, we detect only tentative F770W emission of 7.9 ± 2.8 nJy at 2.8 σ significance, constraining the total equivalent width of [O iii ] λλ 4959, 5007 + H β to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>52</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>380</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>400</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> Å, weaker than most z > 10 galaxies with MIRI detections. This source is unresolved across 16 NIRCam bands, implying a physical radius ≲50 pc. NIRSpec/PRISM spectroscopy totaling 56 hr reveals no rest-frame ultraviolet emission lines above 3 σ . Stellar population synthesis suggests a stellar mass ∼4 × 10 7 M ⊙ and a star formation rate ∼2 M ⊙ yr −1 . The absence of strong metal emission lines despite intense star formation suggests a gas-phase metallicity below 10% solar and potentially a high escape fraction of ionizing photons. These deep observations provide rare constraints on faint, early galaxies, tracing the onset of chemical enrichment and ionization in the early Universe.
Authors
- Francesco D’Eugenio (ORCID: https://orcid.org/0000-0003-2388-8172)
- Joris Witstok (ORCID: https://orcid.org/0000-0002-7595-121X)
- Zhiyuan Ji (ORCID: https://orcid.org/0000-0001-7673-2257)
- George H. Rieke (ORCID: https://orcid.org/0000-0003-2303-6519)
- Santiago Arribas (ORCID: https://orcid.org/0000-0001-7997-1640)
- Jakob M. Helton (ORCID: https://orcid.org/0000-0003-4337-6211)
- Fengwu Sun (ORCID: https://orcid.org/0000-0002-4622-6617)
- Benjamin D. Johnson (ORCID: https://orcid.org/0000-0002-9280-7594)
- Stefano Carniani (ORCID: https://orcid.org/0000-0002-6719-380X)
- Kevin Hainline (ORCID: https://orcid.org/0000-0003-4565-8239)
- Jacopo Chevallard (ORCID: https://orcid.org/0000-0002-7636-0534)
- Sandro Tacchella (ORCID: https://orcid.org/0000-0002-8224-4505)
- Chris J. Willott (ORCID: https://orcid.org/0000-0002-4201-7367)
- Xihan Ji (ORCID: https://orcid.org/0000-0002-1660-9502)
- S. Charlot (ORCID: https://orcid.org/0000-0003-3458-2275)
- Mirko Curti (ORCID: https://orcid.org/0000-0002-2678-2560)
- Tiger Yu-Yang Hsiao (ORCID: https://orcid.org/0000-0003-4512-8705)
- Christina C. Williams (ORCID: https://orcid.org/0000-0003-2919-7495)
- Tobias J. Looser (ORCID: https://orcid.org/0000-0002-3642-2446)
- Yongda Zhu (ORCID: https://orcid.org/0000-0003-3307-7525)
- Pierluigi Rinaldi (ORCID: https://orcid.org/0000-0002-5104-8245)
- Daniel J. Eisenstein (ORCID: https://orcid.org/0000-0002-2929-3121)
- James Trussler (ORCID: https://orcid.org/0000-0002-9081-2111)
- Stacey Alberts (ORCID: https://orcid.org/0000-0002-8909-8782)
- P. Jakobsen (ORCID: https://orcid.org/0000-0002-6780-2441)
- Jan Scholtz (ORCID: https://orcid.org/0000-0001-6010-6809)
- Emma Curtis-Lake (ORCID: https://orcid.org/0000-0002-9551-0534)
- Christopher N. A. Willmer (ORCID: https://orcid.org/0000-0001-9262-9997)
- William Baker (ORCID: https://orcid.org/0000-0003-0215-1104)
- Andrew J. Bunker (ORCID: https://orcid.org/0000-0002-8651-9879)
- Brant E. Robertson (ORCID: https://orcid.org/0000-0002-4271-0364)
- Zihao Wu (ORCID: https://orcid.org/0000-0002-8876-5248)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2025-10-17
- DOI
- https://doi.org/10.3847/1538-4357/ae01a1
- Citations
- 5
- Primary Topic
- Galaxies: Formation, Evolution, Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 5.77
Funders
- National Science Foundation
- National Aeronautics and Space Administration
- University of California, Santa Cruz
- Villum Fonden
- Dell EMC
- Space Telescope Science Institute
- UK Research and Innovation
- European Commission
- National Research Foundation
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
- Danmarks Grundforskningsfond
- Nuclear Safety and Security Commission
- Ministerio de Ciencia e Innovación
- Goddard Space Flight Center
- Engineering and Physical Sciences Research Council
- Science and Technology Facilities Council
- Agencia Estatal de Investigación