The eventful life of a luminous galaxy at z = 14: metal enrichment, feedback, and low gas fraction?

¹ Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
² Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
³ Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE, UK
⁴ INAF – Osservatorio Astronomico di Brera, via Brera 28, I-20121 Milano, Italy
⁵ Center for Astrophysics | Harvard & Smithsonian, 60 Garden St., Cambridge MA 02138 USA
⁶ Department of Space, Earth, & Environment, Chalmers University of Technology, Chalmersplatsen 4 412 96 Gothenburg, Sweden
⁷ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
⁸ Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
⁹ National Astronomical Observatory of Japan, 2 Chome-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan
¹⁰ Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721, USA
¹¹ Cosmic Dawn Center (DAWN), Copenhagen, Denmark
¹² Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
¹³ Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98 bis bd Arago, 75014 Paris, France
¹⁴ Niels Bohr Institute, University of Copenhagen, Jagtvej 128, DK-2200, Copenhagen, Denmark
¹⁵ AURA for European Space Agency, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21210, USA
¹⁶ Department of Astronomy and Astrophysics, University of California, Santa Cruz, 1156 High Street, Santa Cruz CA 96054, USA
¹⁷ NSF's National Optical-Infrared Astronomy Research Laboratory, 950 North Cherry Avenue, Tucson, AZ 85719, USA
¹⁸ NRC Herzberg, 5071 West Saanich Rd, Victoria, BC V9E 2E7, Canada

Received: 1 October 2024
Accepted: 28 February 2025

Abstract

JADES-GS-z14-0 is the most distant spectroscopically confirmed galaxy yet, at z≳14. With a UV magnitude of –20.81, it is one of the most luminous galaxies at cosmic dawn and its half-light radius of 260 pc means that stars dominate the observed UV emission. We report the Atacama Large Millimeter/submillimeter Array (ALMA) detection of [O III]88 μm line emission with a significance of 6.67σ and at a frequency of 223.524 GHz, corresponding to a redshift of 14.1796±0.0007, which is consistent with the candidate C III] line detected in the NIRSpec spectrum. At this spectroscopic redshift, the Lyman-α break identified with NIRSpec requires a damped Lyman-α absorber with a column density of log(N_HI/cm⁻²) = 21.96. The total [O III]88 μm luminosity (log(L_[OIII]/L_⊙) = 8.3±0.1) is fully consistent with the local L_[OIII]−SFR relation and indicating a gas-phase metallicity >0.1 Z_⊙. Using prospector spectral energy distribution (SED) modeling and combining the ALMA data with JWST observations, we find Z = 0.17 Z_⊙ and a non-zero escape fraction of ionizing photons (∼11%), which is necessary by the code to reproduce the UV spectrum. We measure an [OIII]5007 Å/[OIII]88 μm line flux ratio between 1 and 20, resulting in an upper limit to the electron density of roughly 700 cm⁻³ assuming a single-cloud photoionization model. The [O III]emission line is spectrally resolved, with a FWHM of 102₋₂₂⁺²⁹km s⁻¹, resulting in a dynamical mass of log(M_dyn/M_⊙) = 9.0±0.2. When compared to the stellar mass, this value represents a conservative upper limit on the gas mass fraction, which ranges from 50% to 80%, depending on the assumed star formation history. Past radiation-driven outflows may have cleared the galaxy from the gas, reducing the gas fraction and thus increasing the escape fraction of ionizing photons.