JADESGSz140 is the most distant spectroscopically confirmed galaxy so far at zgt14. With a UV magnitude of 20.81 it is one of the most luminous galaxies at cosmic dawn and its halflight radius of 260 pc means that stars dominate the observed UV emission. We report the ALMA detection of OIII88mum line emission with a significance of 6.67sigma and at a frequency of 223.524 GHz corresponding to a redshift of 14.1796pm0.0007 which is consistent with the candidate CIII line detected in the NIRSpec spectrum. At this spectroscopic redshift the Lyman break identified with NIRSpec requires a damped Lymanalpha absorber with a column density of logNrm HImathrmcm222.23. The total OIII88mum luminosity logLrm OIIILodot  8.3pm0.1 is fully consistent with the local Lrm OIIISFR relation. Based on the Lrm OIIISFR we infer a gasphase metallicity gt0.1rm Zrm odot which is somewhat unexpected given the weakness of the UV emission lines. Using prospector SED modeling and combining the ALMA data with JWST observations we find Z0.17Zrm odot and an escape fraction of ionizing photons of 20 which is necessary to explain the UV spectrum. We measure an O III5007O III88mum line flux ratio between 1 and 10 resulting in an upper limit to the electron density of roughly 300 cm3 which is lower than those measured in other highz luminous galaxies. The OIII88mum emission line is spectrally resolved with a FWHM of 100 kms resulting in a dynamical mass of logMrm dynModot  9.0pm0.2. This value is comparable to the stellar mass derived from the SED fitting which implies a very low gas fraction. Past radiationdriven outflows may have cleared the galaxy from the gas reducing the gas fraction and thus increasing the escape fraction of ionizing photons.
['Astrophysics - Astrophysics of Galaxies', 'Astrophysics - Cosmology and Nongalactic Astrophysics']
The eventful life of a luminous galaxy at z  14 metal enrichment feedback and low gas fraction
{'The eventful life of a luminous galaxy at z = 14 : metal enrichment, feedback, and low gas fraction?': "Stefano Carniani 1 , Francesco D'Eugenio 2 , 3 , 4 , Xihan Ji 2 , 3 , Eleonora Parlanti 1 , Jan Scholtz 2 , 3 , Fengwu Sun 5 , Giacomo Venturi 1 , Tom J. L. C. Bakx 6 , Mirko Curti 7 , Roberto Maiolino 2 , 3 , 8 , Sandro Tacchella 2 , 3 , Jorge A. Zavala 9 , Kevin Hainline 10 , Joris Witstok 11 , 3 , Benjamin D. Johnson 5 , Stacey Alberts 10 , Andrew J. Bunker 12 , Stéphane Charlot 13 , Daniel J. Eisenstein 5 , Jakob M. Helton 10 , Peter Jakobsen 11 , 14 , Nimisha Kumari 15 , Brant Robertson 16 , Aayush Saxena 12 , 8 , Hannah Übler 2 , 3 , Christina C. Williams 17 , Christopher N. A. Willmer 10 , and Chris Willott 18  \n- 1 Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy\n- 2 Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK\n- 3 Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE, UK\n- 4 INAF - Osservatorio Astronomico di Brera, via Brera 28, I-20121 Milano, Italy\n- 5 Center for Astrophysics | Harvard & Smithsonian, 60 Garden St., Cambridge MA 02138 USA\n- 6 Department of Space, Earth, & Environment, Chalmers University of Technology, Chalmersplatsen 4 412 96 Gothenburg, Sweden\n- 7 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany\n- 8 Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK\n- 9 National Astronomical Observatory of Japan, 2 Chome-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan\n- 10 Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721, USA\n- 11 Cosmic Dawn Center (DAWN), Copenhagen, Denmark\n- 12 Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK\n- 13 Sorbonne Université, CNRS, UMR 7095, Institut d'Astrophysique de Paris, 98 bis bd Arago, 75014 Paris, France\n- 14 Niels Bohr Institute, University of Copenhagen, Jagtvej 128, DK-2200, Copenhagen, Denmark\n- 15 AURA for European Space Agency, Space Telescope Science Institute, 3700 San Martin Drive. Baltimore, MD, 21210\n- 16 Department of Astronomy and Astrophysics University of California, Santa Cruz, 1156 High Street, Santa Cruz CA 96054, USA\n- 17 NSF's National Optical-Infrared Astronomy Research Laboratory, 950 North Cherry Avenue, Tucson, AZ 85719, USA\n- 18 NRC Herzberg, 5071 West Saanich Rd, Victoria, BC V9E 2E7, Canada  \nOctober 1, 2024", '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 µ mline emission with a significance of 6.67 σ 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 Lymanα break identified with NIRSpec requires a damped Lymanα absorber with a column density of log( N HI / cm -2 ) = 22 . 23. The total [O iii ] 88 µ m luminosity (log( L [OIII] / L ⊙ ) = 8 . 3 ± 0 . 1) is fully consistent with the local L [OIII] -SFR relation. Based on the L [OIII] / S FR we infer a gas-phase metallicity > 0 . 1 Z ⊙ , which is somewhat unexpected given the weakness of the UV emission lines. Using prospector spectral energy distribution (SED) modeling and combining the ALMA data with JWST observations, we find Z = 0 . 17 Z ⊙ and an escape fraction of ionizing photons of 20%, which is necessary to explain the UV spectrum. We measure an [OIII]5007Å / [OIII]88 µ mline flux ratio between 1 and 10, resulting in an upper limit to the electron density of roughly 300-400 cm -3 , which is lower than those measured in other highz luminous galaxies. 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. This value is comparable to the stellar mass derived from the SED fitting, which implies a very low gas fraction in this galaxy. 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.', '1. Introduction': "One of the most exciting and puzzling coming out of observations with JWST is the discovery of numerous luminous ( M UV < -20) galaxies already in place 300-500 Myr after the Big Bang (Arrabal Haro et al. 2023; Bunker et al. 2023b; Curtis-Lake et al. 2023; Robertson et al. 2023; Wang et al. 2023; Castellano et al. 2024; Carniani et al. 2024; Zavala et al. 2024). Indeed, the number of such bright galaxies at z > 10 is up to one order of magnitude higher than what was extrapolated based on both preJWST observations and cosmological simulations (e.g., Finkelstein et al. 2023; Donnan et al. 2024; Robertson et al. 2024).  \nSuch observations have raised several questions about the formation of first galaxy populations, and some studies have suggested a slow decline in the number density of galaxies at z > 12, with increasing e ffi ciency of galaxy formation in halos at higher redshifts (e.g., Dekel et al. 2023; Robertson et al. 2024). Other studies suggest that the overabundance of ultraviolet-luminous galaxies can be also explained with an attenuation-free model (Ferrara et al. 2023; Ferrara 2023). This assumes that the radiation pressure of the stars expels gas and dust from the galaxy reducing the dust attenuation and boosting the observed UV emission. Alternatively, stochasticity in the galaxy luminosities and star-formation rate (SFR) at fixed halo mass (Mason et al. 2023;  \nMirocha & Furlanetto 2023; Shen et al. 2023), a top-heavy initial mass function (Inayoshi et al. 2022; Trinca et al. 2024), and a contribution from accreting black holes (Inayoshi et al. 2022; Trinca et al. 2024; Hegde et al. 2024) are other possible scenarios that can explain the observed UV luminosity function at the Cosmic Dawn.  \nThe study of the UV luminosity function alone is not su ffi -cient to distinguish the various models. However, each model is expected to make di ff erent predictions regarding the stellar population and interstellar medium (ISM) properties of such luminous galaxies; constraining these galaxies through observations would thus allow us to discern among the models and break the degeneracies encountered on the population level. However, the properties derived from the spectral energy distribution (SED) fitting of the most distant galaxies are not well-constrained and are highly degenerate between each other, particularly because the available photometry usually only probes the rest-frame UV emission (i.e., there is a strong degeneracy between the stellar mass, dust attenuation law, and star-formation history). To make further progress additional data at other wavelengths are extremely valuable.  \nTo date, JADES-GS-z14-0 is the most distant galaxy known so far (Robertson et al. 2024; Helton et al. 2024; Carniani et al. 2024). With a UV luminosity of M UV ∼ -21, this galaxy is among the most luminous galaxies at z > 8 in GOODSS and GOODS-N CANDELS fields (Hainline et al. 2024b). It is two times more luminous than the GHZ2 at z = 12 . 33 ( M UV ∼ -20 . 5; Castellano et al. 2024) and nearly as luminous as GN-z11 at z = 10 . 6 ( M UV ∼ -21 . 5; Tacchella et al. 2023; Bunker et al. 2023b). NIRCam observations reveal that JADES-GS-z14-0 is spatially resolved with a half-light radius of 260 pc (0.079 '' ), indicating its emission is dominated by light from the stellar population and does not arise from an active galactic nucleus (AGN). The galaxy has also been detected in a 43-h MIRI pointing at 7.7 µ m, with excess wideband emission likely indicating strong emission lines from [O iii ] λλ 4959 , 5007 and H β , corresponding to a rest-frame equivalent width EW ([O iii ] λλ 4959 , 5007 + H β ) = 370Å (Helton et al. 2024).  \nThe JWST / NIRSpec follow-up observations have revealed a prominent sharp Lymanα break, indicating a redshift of z = 14 . 32 + 0 . 08 -0 . 20 (Carniani et al. 2024). As the Lymanα break profile is sensitive to the column density of neutral hydrogen along the line of sight, the uncertainties on the spectroscopic redshift are quite large and asymmetric toward low values, whose probability is not negligible given the recent discovery of damped Lyman systems at very high redshifts (Hsiao et al. 2023; Heintz et al. 2024a; D'Eugenio et al. 2023; Hainline et al. 2024a; Witstok et al. 2024). Despite the deep observations, the NIRSpec spectrum does not show any clear rest-frame UV emission lines. There is only a tentative (3.6 σ ) detection of C iii ] λλ 1907 , 1909 at 2.89 µ m, which would yield a redshift of 14.178 ± 0.013. If this redshift is confirmed, it would require the presence of a damped Lymanα absorber (DLA) with a hydrogen column density of log( N HI / cm -2 ) = 22 . 23 to explain the redshifted Lymanα break (Carniani et al. 2024).  \nThe SED fitting of JWST photometric and spectroscopic data indicates an ongoing star-formation rate (SFR) of 19 M ⊙ / yr and a stellar mass of 4 × 10 8 M ⊙ . The latter su ff ers from large uncertainties (0.4 dex) due to the unknown origin of the excess MIRI flux at 7 µ m (Helton et al. 2024). The spectral modelling suggests that one-third of the MIRI flux is associated with the restoptical nebular emission lines [O iii ] λλ 4959 , 5007 and H β , but the results depend on the star-formation history priors adopted  \nin the SED fitting (which are highly uncertain at these high redshifts, Tacchella et al. 2022b; Whitler et al. 2023).  \nThe absence of bright UV emission lines in NIRSpec spectrum sets only upper limits (with significant uncertainties) on the properties of the ISM. Additional multi-wavelength observations are thus fundamental to constrain the galaxy and ISM properties and provide deeper insights into the galaxy evolution of JADESGS-z14-0.  \nIn this paper, we combine JWST data with the public ALMA observations (DDT 2023.A.00037.S, PI: S. Schouws) of JADESGS-z14-0. The observations carried out in the frequency range between 218 and 229 GHz allow us to identify the far-infrared oxygen line [O iii ] at rest-frame 88 µ m and determine the redshift of the galaxy with high accuracy. In addition to that, the far-infrared line probes the gas-phase metallicity and then, combined with the MIRI data, allows us to constrain the electron density. Finally, the continuum emission allows us to study the dust content and investigate the nature of the moderate optical dust attenuation ( A V = 0 . 3) determined from the JWST data.  \nThroughout this paper, we adopt the standard cosmological parameters H0 = 70 kms -1 Mpc -1 , Ω M = 0 . 30, ΩΛ = 0 . 70, according to which 1 arcsec at z = 14 corresponds to a proper distance of 3.268 kpc. Astronomical coordinates and magnitudes are given in the ICRS and AB systems, respectively. Abundance patterns are from Anders & Grevesse (1989) unless stated otherwise.", '2. ALMA observations and data reduction': "JADES-GS-z14-0 was observed with ALMA Band 6 as part of 2023.A.00037.S program, in two spectral configurations to target the [O iii ] 88 µ m emission line and cover 98% of the redshift probability distribution reported in Carniani et al. (2024). Each spectral configuration was observed for 2.82 hours of onsource integration time. The calibrated visibilities were downloaded from the ALMA archive. The first spectral configuration was observed with ALMA configuration C4, while the second one with configuration C5, hence the two spectral configurations have di ff erent spatial resolutions.  \nWe performed the cleaning on the calibrated visibilities using the Common Astronomy Software Applications package (CASA; McMullin et al. 2007) task tclean . To optimize the sensitivity to detect the [O iii ] emission line, we adopted a natural and briggs robust = 0.5 weighting scales, hogbom deconvolver, a spaxel scale of 0.1 '' , and a channel width of 10 km s -1 to create the final datacubes. The final datacubes for the first spectral configuration have a beam size of 0.82 '' × 0.60 '' and 1.09 '' × 0.82 '' for the briggs robust = 0.5 and natural cubes, respectively. For the second spectrum configuration, we obtain datacubes with 0.42 '' × 0.38 '' and 0.58 '' × 0.50 '' for the briggs robust = 0.5 and natural cubes, respectively.  \nWe also imaged the dust-continuum emission at 88 µ m restframe by using the 'mfs' mode of the task tclean using natural weighting to maximize the S / N. The final continuum image has a beam size of 0.66 '' × 0.84 '' and a sensitivity of 4.4 µ Jy beam -1 .", '3. Data analysis': 'The frequency range of these ALMA observations covers about 98% (Fig. 1) of the posterior distribution function of the spectroscopic redshift determined from the fitting of the Lyman-break profile of JWST / NIRSpec data (Carniani et al. 2024). Given the large uncertainty on the spectroscopic redshift, we have performed a blind-line search in the ALMA datacube. In particular,  \nFig. 1: [O iii ] 88 µ m spectrum (left) and flux map (right) of JADES-GS-z14-0. The top panel illustrates the redshift probability distribution determined from the JWST / NIRSpec data. The red vertical dotted line shows the redshift determined from the candidate C iii ] detection (Carniani et al. 2024). The black contours in the flux map show ± 3, ± 4, ± 5, and ± 6 σ of [O iii ] emission, while red contours correspond to the rest-frame UV emission from JWST / NIRCam F200W observations.  \n<!-- image -->  \nwe have analyzed the region of the datacube enclosed within 5 arcsec from the location of the target. The adopted customized line finder code was already used in other ALMA studies (e.g., Maiolino et al. 2015; Carniani et al. 2017, 2020) and was optimized to identify point-like sources in datacubes without defining a priori the line width of the emission line. More details of the code are explained in Appendix B of Carniani et al. (2020).  \nAt the location of the galaxy, we have identified an [O iii ] emission line with a significance level at 6.67 σ at a frequency of 223.524 GHz, which corresponds to a redshift of 14 . 1796 ± 0 . 0007. Fig. 1 shows the spectrum of the detected line and the integrated map. The line has a full width at half maximum (FWHM) of 102 + 29 -22 km s -1 and an integrated flux density of 0 . 037 ± 0 . 009 Jy km s -1 , resulting in an [O iii ] luminosity log( L [OIII] / L ⊙ ) = 8 . 3 ± 0 . 1. We checked whether the detection could be due to a line associated to the foreground galaxy at z = 3 . 475 located close to JADES-GS-z14-0 to its East (Carniani et al. 2024). We find no line species that would be redshifted to a frequency of 223.524 GHz given the above redshift.  \nWe have also analyzed the continuum map, but no signal at the spatial position of the [O iii ] 88 µ mline emission has been detected. We have thus derived a 3 σ upper limit on the continuum emission for a point-like source of S 88 µ m < 13 µ Jy.  \nThe fidelity of the ALMA emission line detection is verified in Appendix A. We note that there is an additional 3.7 σ signal in the [O iii ] moment-0 map at the same redshift 2.5 arcsec NW from JADES-GS-z14-0. Given the low significance and the lack of continuum detection in the NIRCam images, we do not consider this additional 3.7σ signal as a solid detection.', '4.1. Dust content': 'As the dust thermal emission is not detected in the ALMA continuum map at 88 µ m, we estimate an upper limit on dust mass. We assume a typical single-temperature modified black body function (e.g., equation 1 in Carniani et al. 2019) to reproduce the dust thermal emission spectral-energy distribution in the restframe far-infrared. We adopt a dust opacity coe ffi cient at 250 GHz of 0.45 g cm -2 and an emissivity index of β = 1 . 8 (Witstok  \net al. 2023), and correct for the e ff ect of the cosmic microwave background following da Cunha et al. (2013). Given the modified black body function, the flux at 88 µ mdepends on dust mass and temperature.  \nFigure 2 shows the 3 σ upper limits on the dust mass as a function of the dust temperature, based on the continuum sensitivity of the DDT ALMA program. The dust mass cannot be constrained with only one ALMA measurement due to the degeneracy with the dust temperature. In addition to that, if we assume that the dust temperature is lower than 60 K, the continuum sensitivity is not su ffi cient to put any constraint on the dust enrichment mechanism. The upper limits on the dust-to-stellar mass ratio at low temperatures are higher than 0.002 (vertical black dashed line in Figure 2). Such value is higher than the typical dust-to-stellar mass ratio observed in highz galaxies (Witstok et al. 2022) and expected by theoretical models assuming that at such early times dust enrichment mechanism is mainly associated with supernova ejecta (Schneider & Maiolino 2024). This means that in the hypothesis of low temperatures, the depth of current observations is not su ffi cient to put any constraints on the dust content.  \nWe note that the upper limit on the continuum emission is consistent with the recent predictions by Ferrara et al. (2024). The authors show that the flux at 88 µ m depends on both the dust-to-stellar mass ratio and the extension of the dust. In their fiducial case with dust-to-stellar equal to 1 / 529, the dust is expected to be extended up to 1.4 kpc to reproduce the inferred A V from Carniani et al. (2024), have a luminosity-weighted temperature of 72 K, and a flux of about 15 µ Jy.  \nIn conclusion, the continuum sensitivity of this DDT program does not provide any information about the dust content in JADES-GS-z14-0 and deeper future observations are needed to unveil the dust content in the galaxy and investigate the formation (and destruction) of dust grains in the early Universe.', '4.2. DLA': "We detect an emission line at 6.7 σ which we associate with the [O iii ] 88 µ mtransition, implying a spectroscopic redshift of z = 14 . 1796 ± 0.0007. The [O iii ] redshift is within the probability distribution function of redshifts inferred from the Ly-  \nSED fitting (see Section 5). We adopt this value as the fiducial value.  \nFig. 2: Predicted continuum flux density at the rest-frame wavelength 88 µ m as a function of dust temperature and dust mass. The red line shows the 3 σ sensitivity of the DDT ALMA program of JADES-GS-z14-0. The top axis shows the dust-to-stellar mass ratio for the stellar mass of JADES-GS-z14-0 ( M star = 10 8 . 6 M ⊙ ). The vertical dashed line shows the expected dust-tostellar mass ratio for the supernova dust enrichment mechanism, and black circles illustrate the current measurements in galaxies at z > 7. The CMB temperature at z = 14 is 41 . 7 K (dashed region).  \n<!-- image -->  \nman break analysis for this galaxy (top panel of Figure 1) and is consistent with the redshift from the tentative detection of C iii ] of 14.178 ± 0.013 (Carniani et al. 2024). This redshift, however, is lower than what was predicted from the Ly α break alone ( z = 14 . 32), and indicates the presence of additional damped Ly α absorption for the source, in agreement for what has been observed in other galaxies at z > 10 (Heintz et al. 2024b; Umeda et al. 2024; D'Eugenio et al. 2024a; Hainline et al. 2024a; Heintz et al. 2024a; Witstok et al. 2024).  \nUsing the redshift determined from the detected far-infrared line, we explore the potential need for a DLA to explain the Lyman break profile. To that end, we fit the slit-loss-corrected NIRSpec spectrum with a power-law function of the form f λ ∝ λ -β and apply the attenuation we would expect from the host galaxy ISM or circumgalactic medium column density of neutral hydrogen ( N HI) along the line of sight as modeled in Witstok et al. (2024) and Hainline et al. (2024a). From this fit, we measure a hydrogen column density of log( N HI / cm -2 ) = 22 . 23 for JADESGS-z14-0, which is in agreement with that determined from the  \nThis column density, which is similar to those measured in other, intrinsically fainter, high-redshift galaxies, indicates the presence of a large reservoir of pristine gas surrounding JADESGS-z14-0. The presence of a strong DLA in JADES-GS-z14-0 may indicate that we are observing the source still in the process of assembly and growth. This result may be surprising given its observed brightness and the lack of similar sources found at later cosmic times (Carniani et al. 2024). The location, and extent of the DLA with respect to the host galaxy is still uncertain, however. In Section 6, we discuss the escape fraction of ionizing radiation in JADES-GS-z14-0 and the potential for a fast outflow in this source, which may have contributed to the DLA we observe.  \nThe smoothness of the Ly α break, implied by the redshift measured via [O iii ] and C iii ] being slightly lower than expected from the break alone, can alternatively be explained by invoking an unusually strong two-photon nebular continuum (Katz et al. 2024). This would require the nebular continuum to dominate in the rest-frame UV, which only occurs in the presence of very hot ionising sources ( T e ff ≳ 10 5 K) and at gas densities of n ≲ 10 5 cm -3 (Cameron et al. 2024). In this case, the two-photon radiative decay from the 2 s state produces prominent continuum emission with a characteristic, fixed shape featuring a smooth 'rollover' redwards of Ly α similar to DLA absorption (Spitzer &Greenstein 1951). Given its remarkably low gas fraction (Section 5.1) and potentially high ionising-photon escape fraction (Section 6), both of which may argue against the large column densities of neutral hydrogen implied in the DLA scenario, the two-photon continuum may indeed play a role in shaping the Ly α break of JADES-GS-z14-0.", '4.3. [OIII] 88 µ m luminosity': "We inferred the [O iii ] 88 µ m luminosity from the 6.7 σ detection at 223.524 GHz. We estimated the measured [O iii ] luminosity by following Carilli & Walter (2013) and corrected for a modest lensing magnification factor of 1.17 (Carniani et al. 2024), resulting in log10(L[OIII] / L ⊙ ) = 8 . 3 ± 0 . 1. We compare the [O iii ] luminosity to the SFR in the top panel of Figure 3, alongside other high-redshift detections (Harikane et al. 2020; Witstok et al. 2022; Fujimoto et al. 2024) and local low-metallicity dwarf galaxies (De Looze et al. 2014).  \nThe [O iii ] detection of JADES-GS-z14-0 falls slightly below the local and highz [O iii ]-SFR observed relations but they agree within the uncertainties. This excludes that JADES-GS-z14-0 is extremely metal-poor ( Z < 0 . 05 Z ⊙ ). Indeed, as shown in the bottom panel of Figure 3, the [O iii ] depends both on SFR and gas-phase metallicity, and galaxies with Z < 0 . 05 Z ⊙ fall below the local relation. For example, IZw18 and SBS0335-052, which have a gas-phase metallicity of about 3% solar (De Looze et al. 2014), show a L [OIII] deficit of 0.2-0.3 dex relative to the local relation. The ratio between L [OIII] and SFR of JADESGS-z14-0 is similar to those measured in dwarf galaxies with 0 . 05 Z ⊙ < Z < 1 Z ⊙ . However, we cannot exclude a lower metallicity scenario given that L [OIII] / SFR is also sensitive to the ionization parameter and electron density.  \nIn Figure 4 we combine JWST / MIRI and ALMA data to determine the region covered by JADES-GS-z14-0 in the L [OIII]5007Å / L H β versus L [OIII]5007Å / L [OIII]88 µ m diagram. Since [O iii ] λ 5007 and H β are not spectrally resolved in MIRI, we vary L [OIII]5007Å / L H β from 0.1 to 10, which is a plausible range for metal-poor galaxies with di ff erent ionization conditions. For  \nFig. 3: L [OIII] versus SFR (top panel) and L [OIII] / SFR versus gasphase metallicity (bottom panel). The red circle and horizontal line (in top and bottom panels, respectively) mark the measurement for JADES-GS-z14-0. Gray circles are local dwarf galaxies, while green pentagons are z ∼ 6 -9 galaxies. The solid blue line shows the local relation by De Looze et al. (2014) for metal-poor galaxies, with the shaded area corresponding to the 1 σ uncertainty. The blue dashed line illustrates the L [OIII] -SFR relation for highz galaxies by Harikane et al. (2020). Dotted and dashed gray lines illustrate the Cloudy models for di ff erent gasphase metallicities and electron densities (Harikane et al. 2020; Jones et al. 2020).  \n<!-- image -->  \neach combination of L [OIII]5007Å / L H β , we use the MIRI excess flux at 7 µ m( ∆ f = 27 . 5 ± 5 . 6 nJy; Helton et al. 2024) as the total flux of the blend, and calculate the possible value of L [OIII]5007Å and thus L [OIII]5007Å / L [OIII]88 µ m. We note that these estimates are independent on the SFR and thus on the models assumed later in the SED fittings. The line ratios we show are corrected for dust attenuation. To illustrate the e ff ect of dust attenuation, we plot a  \nreddening vector corresponding to A V = 0 . 25 (as constrained by the SED fitting later in Sec. 5) assuming an average SMC extinction law (Gordon et al. 2003). Due to the low A V, the reddening correction for L [OIII]5007Å / L [OIII]88 µ m is not sensitive to the choice of the extinction curve.  \nFor comparison, we also show in Figure 4 predictions from photoionization models computed with the code C loudy (c17.03, Ferland et al. 2017) with a range of metallicities, ionization parameters, and gas densities. We summarize the full set of model parameters in Tab. 1. In brief, we assume the gas is photoionized by radiation from a 1 Myr-old simple stellar population (SSP) generated by the Binary Population and Spectral Synthesis code (BPASS v2.3, Eldridge et al. 2017; Stanway & Eldridge 2018; Byrne et al. 2022). We allow the stellar metallicity to vary from 5% solar to 20% solar and match the gasphase metallicity with the stellar metallicity. Dust depletion is included such that 40% of oxygen from the gas is depleted onto dust grains (Cowie & Songaila 1986; Jenkins 1987). We vary the dimensionless ionization parameter, defined as U ≡ Q 0 / n H c ( Q 0 is the ionizing photon flux, n H is the hydrogen density, and c is the speed of light), from -3 . 5 to -1, and the density in a range of 10 ≤ n H / cm -3 ≤ 10 4 . For the equation of state (EoS), we assume the gas is isobaric.  \nThe constraints imposed by the ALMA and MIRI observations set upper limits on the electron density ( n e) of JADES-GSz14-0 depending on the metallicity. By interpolating the model grids linearly in the logarithmic space of n H and U using the griddata function in the scipy package (Virtanen et al. 2020), we obtain density upper limits of n H;uplim = 180 cm -3 ( Z / Z ⊙ = 0 . 05), 300 cm -3 ( Z / Z ⊙ = 0 . 1), and 420 cm -3 ( Z / Z ⊙ = 0 . 2) after dust attenuation corrections. The upper limits on the densities are comparable to those found in galaxies at z = 2 -3 (e.g., Sanders et al. 2016; Kashino et al. 2017; Strom et al. 2017; Davies et al. 2021), but appear lower than galaxies at z > 8 (e.g., Isobe et al. 2023; Abdurro'uf et al. 2024; Marconcini et al. 2024). For example, Isobe et al. (2023) find that galaxies at z = 4 -9 have electron densities higher than n e ∼ 300 cm -3 ( n e ≈ 1 . 1 n H for H ii regions), and the median value for z = 7 -9 is n e ∼ 1000 cm -3 . Furthermore, n e might further increase with increasing z if the relation given by Isobe et al. (2023) is extrapolated to z > 9. As another example, based on the ALMA observation of GHZ2, a bright galaxy at z = 12 . 33, Zavala et al. (2024) infer a density of n e = 100 -3000 cm -3 or higher depending on the assumed temperature. However, we caution that the above high-redshift results are currently based on small number statistics and might be subject to measurement systematics (Sanders et al. 2024).  \nFrom Figure 4, one can see a degeneracy between the ionization parameter and the metallicity. If we constrain n e ≳ 300 cm -3 (i.e., to be higher than the average density in SF galaxies at z = 2 -3, Sanders et al. 2016; Strom et al. 2017), then only the highest metallicity model with Z / Z ⊙ = 0 . 2 [(O / H)gas / (O / H)solar = 0 . 12 after dust depletion] is able to reproduce the observed line ratios, which also constrain the ionization parameter to be -3 ≲ log U ≲ -1 . 5. Considering an observed scatter of roughly 100 cm -3 in the density (Sanders et al. 2016; Strom et al. 2017), models with Z / Z ⊙ = 0 . 1 [(O / H)gas / (O / H)solar = 0 . 06] and -3 ≲ log U ≲ -1 . 5 are also plausible. Again, we caution that the current constraint on the densities at high redshift has large uncertainties and we cannot exclude the possibility that JADESGS-z14-0 is a low-density outlier at high redshift.  \nTable 1: Input parameters for C loudy photoionization models  \nFig. 4: [O iii ] 5007Å / [O iii ] 88 µ m versus [O iii ] 5007Å / H β diagram. Three model grids computed with C loudy are shown, with a range of metallicities from Z / Z ⊙ = 0 . 05 to Z / Z ⊙ = 0 . 2. Each model grid spans a range of ionization parameters ( -3 . 5 ≤ log U ≤ -1) and hydrogen densities (10 cm -3 ≤ n H ≤ 10 4 cm -3 ) in steps of 0.5 dex. Details on model parameters are provided in Tab. 1. The magenta-shaded region shows the plausible attenuation-corrected line ratios for JADES-GS-z14-0 inferred from observations by JWST / MIRI and ALMA. The gray arrow represents a reddening vector with A V = 0 . 25 as constrained by the SED fitting (see Sec. 5) assuming the nebular dust attenuation follows an average SMC extinction curve.  \n<!-- image -->", '5. SED modelling: NIRSpec+NIRCam+MIRI+ALMA': "The combination of ALMA and JWST provides us with new constraints on the SED modelling. We add our ALMA constraints to existing NIR and MIR data; we use NIRSpec / MSA spectroscopy and NIRCam photometry from Carniani et al. (2024), in combination with MIRI F770W photometry from Helton et al. (2024, capturing H β and [O iii ] λλ 4959 , 5007). We adopt the Bayesian inference framework prospector (Johnson et al. 2021), itself relying on fsps (Conroy et al. 2009; Conroy & Gunn 2010) for stellar spectra, and on pre-computed nebular emission from Byler et al. (2017). In our setup, we use MIST isochrones (Choi et al. 2016) and the C3K model atmospheres (Conroy et al. 2019). We use a recent implementa-  \nn 1 . We generally follow the model setup of Tacchella et al. (2022a, hereafter T22). The di ff erences are the IMF (we assume a Chabrier 2003 IMF with lower and upper mass limits of 0.1 and 300 M ⊙ ), a stronger prior on the parameters of the Kriek & Conroy (2013) dust attenuation, the inclusion of a 2 nd -order multiplicative Chebyshev polynomial (to match the shapes of the photometry and of the spectrum), the maximum allowed redshift (no star formation is allowed earlier than z = 30), the addition of a DLA (with variable redshift and column density), and a rising prior on the star-formation history (SFH), following the redshift evolution of the accretion rate of dark-matter haloes. The rising prior is parameterized by the log-ratio of the SFR between each time bin and the previous bin in cosmic time; by default, this prior behaves similarly to the delayedτ models, but we allow substantial freedom by using a probability prior on the log SFR ratio that is a Student's t distribution with scale 1 and ν = 2 (following Leja et al. 2019). The rising prior on the SFH follows the mass accretion rate of dark-matter halos (Tacchella et al. 2018), and will be presented in Turner C. et al. (in prep.). The shape of this prior is shown in Fig. 5f (gray shaded region). The model attempts to reproduce the spectrum (modulo the polynomial scaling), the NIRCam-MIRI photometry, and the ALMA observations, both the [O iii ] λ 88 µ m line flux and the upper limit on the flux density of the dust continuum. The NIRSpec and NIRCam data are from Carniani et al. (2024), the MIRI data is from Helton et al. (2024). Given the redshift measurement from ALMA, we impose a strong Gaussian prior centered on z = 14 . 1796 with dispersion 0 . 0001. A summary of the model parameters is reported in Table 2. We infer the posterior probability distribution of our model parameters using dynesty (Speagle 2020; Koposov et al. 2022). The 1-d marginalized posteriors are also listed in Table 2. Fig. 5 reports the main 1-d and 2-d posterior probabilities (triangle diagram; Fig. 5a), the galaxy's SED (panel b), the normalized residuals (panel c), and the SFH (panel d).  \nWith this setup, we find fiducial (magnification-corrected) log M ⋆/ M ⊙ = 8 . 84 + 0 . 09 -0 . 10 and a log SFR / (M ⊙ yr -1 ) = 1 . 00 + 0 . 08 -0 . 09 . We report the star-formation rate averaged over the previous 10 Myr. To match the redshift of [O iii ] λ 88 µ m with that of the Ly α drop, the model also requires a DLA, with log N H i / cm -2 = 21 . 97 + 0 . 07 -0 . 08 ; this value is in agreement with the fiducial DLA model which gives a value of 22.23 (Section 4.2). We rule out a major role of wavelength-calibration issues between ALMA and NIRSpec, because the redshift from ALMA matches the 3σ tentative detection of C iii ] from NIRSpec itself. The results are in agreement with the power-law fits reported in Section 4.2. We find a metallicity of 0.17 solar, somewhat higher than previous results (Carniani et al. 2024; Helton et al. 2024); this could be driven by the [O iii ] 88 µ mdetection. Our setup finds a lower dust attenuation value and escape fraction than Carniani et al. (2024), however these two parameters are unsurprisingly degenerate. In our fiducial model, the model preference for a low dust attenuation requires a strong nebular continuum to explain the relatively flat UV slope reported by Carniani et al. (2024); this is evident from the presence of a Balmer jump in the posterior model (Fig. 5b). At the same time, the bright flux measured by MIRI requires a moderate contribution from the stellar continuum in addition to H β and [O iii ] λλ 4959 , 5007; this stellar continuum displays a moderate Balmer break ( ≈ 1 . 4, when measured without the nebular continuum). The model finds a [O iii ] λ 5007 / H β flux ratio of 4 . 2 + 0 . 5 -0 . 6 (bottom right histogram in Fig. 5a), some-  \nth the values reported in Helton et al. (2024, which are about two times lower).  \nThe ALMA line flux predicted by the model is degenerate with stellar mass, metallicity, SFR and ionization parameter; these strong degeneracies highlight the constraining power the joint use of ALMA and JWST.  \nThe SFH follows the rising shape of the prior probability, although we note that the prior width is significantly wider than the posterior probability (gray vs red shaded regions in Fig. 5f). We stress that the prior range shown in the SFH is the scale parameter of the Student's t distribution; the prior standard deviation is larger. The key constraints from the prior come at the earliest epochs, when the prior suppresses the earliest and least constrained stages of star formation. There is some indication of the SFH 'stalling' at recent times, with the SFR being roughly constant in the last 30 Myr. This goes against the rising expectation from the prior, which would give a certain degree of confidence to this stalling behavior. However, we also find that di ff erent assumptions on the dust attenuation and prior on the SFH do impact the exact shape of the recovered SFH.", '5.1. Dynamical mass': 'Given that we spectroscopically resolve the emission line in the ALMAobservations, we are now able to constrain the dynamical mass (Mdyn), assuming that the system is close to virialization, and can compare it to the stellar mass from the prospector SED fitting. We estimated the dynamical mass following the approach described by Übler et al. (2023) using the equation:  \nM dyn = K ( n ) K ( q ) σ 2 Re G (1)  \nwhere K(n) = 8.87 - 0.831n + 0.0241n 2 and with Sérsic index n, following Cappellari et al. (2006), K(q) = [0.87 + 0.38e -3 . 71(1 -q ) ] 2 , with axis ratio q following van der Wel et al. (2022), σ is the integrated stellar velocity dispersion, and R e is the e ff ective radius. We remark that the above approach was calibrated for stellar kinematics of massive galaxies at z = 0 . 8 ( M ⋆ = 10 9 -10 11 M ⊙ ). However, a range of possible calibrations (e.g., Wisnioski et al. 2018; Cappellari et al. 2013) provides similar answers, within 0.3 dex (see e.g. Marconcini et al. 2024). We use our measured value of σ = FHWM / 2 . 355 = 43 . 5 + 12 . 3 -9 . 2 km s -1 from [O iii ] 88 µ m, to which we apply a correction of ∆ log( σ/ (km s -1 )) = + 0.1 following Übler et al. (2023), since galaxies with low integrated ionized gas velocity dispersion tend to have higher integrated stellar velocity dispersion (Bezanson et al. 2018). We adopt a R e value of 260 ± 20 pc from Carniani et al. (2024). For JADES-GS-z14-0, Helton et al. (2024) reports n = 0 . 877 ± 0 . 027 for the Sérsic index and q = 0 . 425 ± 0 . 008 for the axis ratio. However, since it is unclear whether the stellar emission in the rest-frame UV has the same morphological properties as the nebular emission in the rest-frame far-infrared, we adopt a range of values for the Sérsic index and axis ratio (n = 0.8-2 and q = 0.3-1). We thus estimate a log(Mdyn / M ⊙ ) = 9.0 ± 0 . 2.  \nThis low value of Mdyn is consistent within the uncertainties with the stellar mass from SED fitting (log M ⋆/ M ⊙ = 8 . 84 + 0 . 09 -0 . 10 , which assumes a Chabrier 2003 IMF). Assuming a disc-like geometry with a mean inclination of i = 60°, this would imply a low fraction of gas mass ( ∼ 30%) and dark matter in this galaxy. Alternatively, if the inclination was very small (close to face on), the line broadening could underestimate the dynamical mass.  \nObservations with higher spatial resolution would be required to address this scenario.', '6. High escape fraction': "The luminosity of the [O iii ] far-infrared line of JADES-GS-z140 indicates a gas-phase metallicity of about 0.2 Z ⊙ , which is similar to that measured in other luminous galaxies such as GN-z11 (Bunker et al. 2023a; Maiolino et al. 2024) and GHZ2 (Castellano et al. 2024; Zavala et al. 2024; Calabro et al. 2024). Although these three galaxies have similar UV luminosities and metal enrichment conditions, most of the UV lines of JADESGS-z14-0 are undetected in the deep NIRSpec observations. The upper limits on the rest-frame equivalent widths of JADES-GSz14-0 are up to seven times lower with respect to those measured in GN-z11 and GHZ2.  \nAhigh escape fraction of ionizing photons might explain the low intensity of UV emission lines in JADES-GS-z14-0. This scenario is also supported by the SED fitting of the combined ALMA and JWST datasets that report an escape fraction of at least 20%, higher than that measured in GN-z11 and GHZ2.  \nThe origin of such a high escape fraction can be the result of fast galactic outflows that expel gas to a large scale and carve the ISM of the galaxy. For example, Ferrara et al. (2024) predict that JADES-GS-z14-0 may have recently experienced a starburst phase and radiation-driven outflows have cleared the galaxy from dust and gas. Current JWST and ALMA data do not have the sensitivity to identify the presence of 'wings' in the emission line profiles tracing outflowing gas. However, the analysis of the dynamical mass suggests that the potential well is dominated by the stellar population and a large fraction of the gas may have been removed from the galaxy. If the observed log( N HI / cm -2 ) = 22 . 23 DLA described in Section 4.2 was a result of a potential galactic outflow, this would help explain its presence while also allowing for a high escape fraction of ionizing radiation.  \nIntriguingly, the implied 20% escape fraction in a source with the luminosity of JADES-GS-z14-0 would imply the rapid formation of a local ionised 'bubble', which would be consistent with the recent detection of a bright Ly α emission in a galaxy at z = 13 (Witstok et al. 2024).", '7. Carbon-to-oxygen abundance ratio': "Leveraging the redshift delivered by the detection of [O iii ] 88 µ m in the ALMA observations, we can confirm the tentative detection of C iii ] previously reported by Carniani et al. (2024) in the JWST / NIRSpec spectrum at 2 . 89 µ m. This allows us, under a number of fiducial assumptions discussed below, to derive the carbon-over-oxygen abundance (C / O) for JADES-GS-z14-0, yielding the most distant measurement of such abundance ratio to date.  \nTo derive C / O, we first corrected the measured C iii ] flux for nebular attenuation assuming AV = 0.25 as inferred from our SED modelling 2 We then derive the C ++ / O ++ abundance from the C iii ] / [O iii ] 88 µ m line ratio adopting pyneb (Luridiana et al. 2015), assuming an electron temperature of T e = 15 , 000 K and an electron density of n e = 100 cm -3 . The assumed T e value is consistent with the best-fit metallicity and ionisation parameter inferred from the SED modelling, and we assume to reside in the low-density regime as suggested by the simultaneous modelling of the [O iii ] 88 µ m / [O iii ] 5007 and [O iii ] 5007 / H β ratios  \n(rest) [  \nm]  \nFig. 5: Summary of prospector SED model. Panel a. Triangle diagram with the marginalised posterior distribution over a subset of the model-free or dependent parameters (see Table 2 for a description of the parameters and their probability prior). Panel b. SED, including wide- and medium-band measured flux densities (diamonds), the spectrum (grey line with grey region as the uncertainty). NIRCam, MIRI and ALMA data are in black, blue and pink, respectively. Model predictions are red circles (flux densities) or the red line (spectrum). The sand-coloured line is the model SED without convolving to the spectral resolution fo the data. Panel c. Model residuals normalised by the uncertainties. Panel d. Same as panel b, but for the FIR region. The orange square is the ALMA [O iii ] flux. Panel e. Same as panel c, but for the FIR region. Panel f. Star-formation history (red), with the prior probability in grey.  \n<!-- image -->  \n(see Figure 4). We then correct the C ++ / O ++ abundance to the total C / O by applying an ionisation correction factor (ICF) derived from the models presented in Berg et al. (2024), under the assumption of log(U) = -2 . 4 and Z = 0.2 Z ⊙ (i.e., the bestfit values from the SED fitting). The total C / O value is there-  \nre log(C / O) = -0 . 72 ± 0 . 13, corresponding to [C / O] = log(C / O)log(C / O) ⊙ = -0.36, where the formal uncertainties are computed by randomly varying the measured fluxes by their errors and repeating the calculation 100 times, taking the standard deviation of the resulting C / O distribution.  \nTable 2: Summary of the parameters, prior probabilities and posterior probabilities of the fiducial prospector SED model (see also Fig. 5a).  \n(1) Parameter name and units (where applicable). (2) Only parameters marked with 'Y' are optimized by prospector ; parameters marked with 'N' are either tied to other parameters (see Column 4), or are calculated after the fit from the posterior distribution (in this case, Column 4 is empty). (3) Parameter description. (4) Parameter prior probability distribution; N ( µ, σ ) is the normal distribution with mean µ and dispersion σ ; U ( a , b ) is the uniform distribution between a and b ; T ( µ, σ, ν ) is the Student's t distribution with mean µ , dispersion σ and ν degrees of freedom; G ( µ, σ ; a , b ) is the normal distribution with mean µ and dispersion σ , truncated between a and b . (5) Median and 16 th -84 th percentile range of the marginalised posterior distribution; for some nuisance parameters we do not present the posterior statistics (e.g., log SFR ratios). † We corrected all extensive quantities for gravitational lensing, using µ = 1 . 17 (Carniani et al. 2024). ‡ The non-parametric SFH is expressed by the logarithm of the SFR between adjacent time bins; we use a 'rising' SFH probability prior, which at each time bin is a T distribution with mean log ratio R ( z ) ≡ log ( S FR ( zi ) / S FR ( zi + 1)), where zi is the redshift of the i th SFH bin and the S FR ( z ) is given by Turner C. et al. (in prep.), their eq. (4).  \nNonetheless, we note that variations in our assumptions on both T e and n e , as well as uncertainties associated with the dust attenuation correction, can have a non-negligible impact onto the final C / O. In the left panel of Figure 6, we show how the final inferred C / Ovalue would change as a function of the C iii ] / [O iii ] 88 µ m line ratio (comparing in particular the observed and dustcorrected value based on the SED-inferred AV) and of the electron temperature, under our fiducial assumption of n e = 100 cm -3 . For instance, at fixed C iii ] / [O iii ] 88 µ m ratio and n e , varying T e between 15 , 000 K (our fiducial value) and 20 , 000K lowers the inferred C / O by ∼ 0 . 45 dex. On the other hand, assuming n e = 300 cm -3 instead of 100 cm -3 (at fixed line ratio and T e ) would lower the C / O by ∼ 0 . 18 dex. We therefore estimate the amount of systematic uncertainty on our C / O derivation associated with di ff erent assumptions on density and temperature by computing the C / O values over a grid in n e and T e spanning n e ∈ [100,300] cm -3 and T e ∈ [10,000, 20,000] K, yielding a final log(C / O) = -0 . 72 ± 0 . 13 ( + 0 . 3 -0 . 6 systematics).  \nIn the right-panel of Figure 6, we finally plot JADES-GSz14-0 on the C / O vs O / H diagram as the red diamond marker. The solid errorbars report the formal statistical uncertainty on C / O from the flux measurement errors (0 . 13 dex), whereas the dashed errorbars encompass the systematic uncertainties ( + 0 . 3 -0 . 6 ) from our assumptions on n e and T e as discussed above. The oxygen abundance is inferred from the best-fit prospector metallicity. For comparison, a compilation of C / Omeasurement at high-z  \nfrom JWST spectroscopy is also shown (see the legend and caption of Figure 6 for details).  \nThe fiducial C / O value measured in JADES-GS-z14-0 appears in line with expectations given its moderate metallicity, and it is consistent within the uncertainties with predictions from galactic chemical evolution models of the solar neighborhood (Kobayashi et al. 2020), as well as with the yields from pure core-collapse Supernovae (CC-SNe) enrichment (Tominaga et al. 2007), in agreement with a rapid and recent history of mass assembly. Nonetheless, we note that even slightly higher C / O values than predicted by pure CC-SNe enrichment, as possibly shown by taking our C / Omeasurement in JADES-GS-z140 at face value, might be indicative of a lower e ff ective oxygen yield, as possibly driven by SNe-driven outflows preferentially expelling oxygen from the ISM following an intense phase of star-formation (as also discussed in Sect. 6), whereas any contribution to Carbon enrichment from evolved, low-mass stars is unlikely given the age of the system.", '8. Conclusions': 'Wehave presented the analysis of the new DDT ALMA program targeting the [O iii ] 88 µ memission in the most distant and luminous galaxy known so far, JADES-GS-z14-0. We have detected the FIR line with a level of significance of 6.67 σ at a frequency of 223.524 GHz. We have thus determined the spectroscopic redshifts of z [OIII] = 14 . 1796 ± 0 . 0007, in excellent agreement with  \n¯  \n<!-- image -->  \nFig. 6: Carbon-over-oxygen abundance for JADES-GS-z14-0. The left-hand panel shows how the final inferred C / O value changes as a function of the C iii ] / [O iii ] 88 µ mline ratio and of the electron temperature, T e , under our fiducial assumption of N e = 100 cm -3 . The observed and dust-corrected C iii ] / [O iii ] 88 µ mratios for JADES-GS-z14-0 are marked in green and yellow, respectively. In the right-hand panel, we report our fiducial C / Omeasurement for JADES-GS-z14-0 on the C / Ovs O / Hdiagram. The oxygen abundance is inferred from the best-fit prospector metallicity reported in Table 2. The C / O value measured in JADES-GS-z14-0 is consistent with pure enrichment from core-collapse Supernovae. We also report for comparison a sample of C / O measurements from JWST compiled from the literature, namely GS-z12 (z = 12.5; D\'Eugenio et al. 2024b), GHZ2 (z = 12.34; Castellano et al. 2024), GN-z11 (z = 10.6; Cameron et al. 2023), MACS0647-JD (z = 10.2; Hsiao et al. 2024), GS-z9-0 (z = 9.4; Curti et al. 2024), ERO-4590 (z = 8.5; Arellano-Córdova et al. 2022), RXCJ2248-ID (z = 6.11; Topping et al. 2024), GLASS-150008 (z = 6.23; Jones et al. 2023), GS-3073 (z = 5.5; Ji et al. 2024). The C / O vs O / H pattern predicted by Galactic Chemical Evolution models of Kobayashi et al. (2020) is shown in blue, whereas the C / Orange allowed by the CC-SNe yields from Tominaga et al. (2007) is marked by the golden region.  \n<!-- image -->  \nthat from the tentative detection of C iii ] ( z CIII] = 14 . 178 ± 0 . 013), and consistent with the Lyman-break redshift ( z Ly α = 14 . 32 + 0 . 08 -0 . 20 ) when accounting for a DLA (log N H i / cm -2 = 21 . 97 + 0 . 07 -0 08 ).  \n. The measured luminosity of the line ( L [OIII] / L ⊙ = 8 . 3 ± 0 . 1) is consistent with the L [OIII] -S FR relation of local dwarf galaxies. The detection of the FIR line indicates a gas-phase metallicity Z > 0 . 1 Z ⊙ and thus suggests a rapid metal enrichment during the earliest phases of galaxy formation. The modest metal enrichment measured in this work is somewhat unexpected, given the lack of most of the rest-frame UV emission lines in the deep NIRSpec spectrum (Carniani et al. 2024). However, the discrepancy between the two observations can be mitigated by assuming a high escape fraction, which would explain the low intensity of UVemission lines despite the modest gas-phase metallicity measured in JADES-GS-z14-0.  \nWe have combined the MIRI flux at 7.7 µ m and the ALMA detection to constrain the interstellar medium condition by using predictions from C loudy models. The excess of MIRI flux, likely associated to the nebular optical lines of oxygen and hydrogen, and the FIR L [OIII] set a stringent upper limit on the electron density of n e < 300 -400 cm -3 at Z = 0 . 1 -0 . 2 Z ⊙ , which is lower than those previously found in several bright sources at z > 9 (e.g., Abdurro\'uf et al. 2024; Marconcini et al. 2024; Zavala et al. 2024), and also lower compared to the average density ( n e ∼ 1000 cm -3 ) expected at z > 9 from the extrapolation of the n e vs. z relation by Isobe et al. (2023). One possible physical reason is that galactic outflows may have expelled gas on large scales and reduced the gas density within the galaxy.  \nTo constrain the properties of the stellar population and interstellar medium we have performed the SED fitting with prospec -tor to the JWST and ALMA data. The inferred star-formation  \nrate and stellar mass are in agreement with those inferred by Carniani et al. (2024) and Helton et al. (2024). We note that prospector results indicate a gas-phase metallicity 17% solar, but it requires an escape fraction of 0.2 to match the NIRSpec spectrum and, therefore, the weakness of the UV emission line. Combining the [O iii ] 88 µ m detection in ALMA with the 3 . 5 σ C iii ] emission detected by JWST / NIRSpec, we also derive a carbon-over-oxygen abundance log(C / O) = -0 . 72 ± 0 . 13 ( + 0 . 3 -0 . 6 ), in agreement with chemical evolution models of the solar neighborhood given the moderate enrichment of the system.  \nWe have spectroscopically resolved the [O iii ] allowing us to measure the dynamical mass of this galaxy of log(Mdyn) = 9.0 ± 0 . 20. We find this measurement consistent with the stellar mass estimated from prospector , implying very little gas content. This supports the scenario that galactic outflow may have carved the interstellar medium, hence reducing the gas reservoir and resulting in a high escape fraction.  \nThis study demonstrates that multi-wavelength observations are necessary to constrain the properties of galaxies at the highest redshifts. However, the detection of only one emission line is not su ffi cient to put stringent constraints on the interstellar medium condition. MIRI spectroscopic observations and deep NIRSpec data would allow us to investigate directly the luminosity of a range of optical and UV emission lines. Combined with ALMA, these lines would provide new insight on the metal enrichment conditions of the galaxy. Deeper and higher frequency ALMA observations capable of probing the dust continuum would also be invaluable, by providing crucial information on the dust content and attenuation.  \nAcknowledgements. This paper makes use of ALMA data: 2023.A.00037.S. ALMA is a partnership of ESO (representing its member states), NSF (USA)  \nand NINS (Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI / NRAO and NAOJ. S.C, EP and GV acknowledge support from the European Union (ERC, WINGS,101040227). FDE, XJ, JS, RM and JW acknowledge support by the Science and Technology Facilities Council (STFC), ERC Advanced Grant 695671 \'QUENCH" and the UKRI Frontier Research grant RISEandFALL. RM also acknowledges funding from UKRI Frontier Research grant RISEandFALL and a research professorship from the Royal Society. AJB and AS acknowledge funding from the "FirstGalaxies" Advanced Grant from the European Research Council (ERC) under the European Union\'s Horizon 2020 research and innovation programme (Grant agreement No. 789056). HÜgratefully acknowledges support by the Isaac Newton Trust and by the Kavli Foundation through a Newton-Kavli Junior Fellowship. The authors acknowledge use of the lux supercomputer at UC Santa Cruz, funded by NSF MRI grant AST 1828315. CNAW and DJE are supported as a Simons Investigator and by JWST / NIRCamcontract to the University of Arizona, NAS5-02015. The Cosmic Dawn Center (DAWN) is funded by the Danish National Research Foundation under grant DNRF140. BER and BDJ acknowledge support by JWST / NIRCam contract to the University of Arizona, NAS5-02015 and BDJ is supported by JWST Program 3215. The research of CCW is supported by NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation.  \nFig. A.1: Statistics of positive and negative peaks from naturalweighted spectral cubes, collapsed with various velocity bin sizes at 30-170 km s -1 . The maximum S / N = 6.67 is seen at the centroid of JADES-GS-z14-0 at 223.524 GHz with a velocity bin size of 130 km s -1 , for which we interpret as an [O iii ] 88 µ mline detection at z = 14 . 1796. This is much more significant than the strongest negative peak seen in the spectral cube ( -5 . 7 σ ). Therefore, we conclude the fidelity of ALMA line detection.  \n<!-- image -->', 'Appendix A: Fidelity of ALMA [O iii ] line detection': "To assess the fidelity of ALMA [O iii ] 88 µ m line detection at 223.524 GHz, we have blindly searched for positive and negative peaks in reduced ALMA spectral cube. Using the natural cube, we first measure noise spectrum from each channel (median: 0.15 mJy beam -1 per 10 km s -1 velocity bin). We then bin the spectral cube with various velocity sizes of 30, 50, ..., 170 km s -1 , respectively, and search for positive and negative peaks in the collapsed spectral cubes over the central 25 '' × 25 '' region. The S / N of detected peaks are computed by the peak brightness divided by the noise spectrum collapsed over the same velocity bin.  \nFigure A.1 summarizes the statistics of positive and negative peaks throughout the collapsed spectral cubes. The maximum S / N of the collapsed spectral cubes is seen at the centroid of JADES-GS-z14-0 with a velocity bin size of 130 km s -1 at a central frequency of 223.524 GHz, for which we interpret as an [O iii ] 88 µ m emission line detection at z = 14 . 1796 ± 0 . 0007. We also examine the noise spectrum and conclude no additional telluric absorption or contamination is present at this frequency. This line detection is much more significant than the strongest negative peak seen within the spectral cube, which is at S / N = -5.73 with velocity bin size of 50 km s -1 . We have also experimented the Briggs-weighted (robust = 0.5) spectral cube and the conclusion is similar, although the line S / N is slightly reduced to 6.22. 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