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

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 Ciii] 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(NHI=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] - S FR 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 nonzero escape fraction of ionizing photons (∼11%), which is necessary by the code to reproduce the UV spectrum. We measure an [OIII]5007A=[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+29 -22 km s-1, resulting in a dynamical mass of log(Mdyn=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 radiationdriven outflows may have cleared the galaxy from the gas, reducing the gas fraction and thus increasing the escape fraction of ionizing photons.