JADES: Carbon enrichment 350 Myr after the Big Bang

Finding the emergence of the first metals in the early Universe and identifying their origin are some of the most important goals of modern astrophysics. We present deep JWST/NIRSpec spectroscopy of GS-z12, a galaxy at z = 12.5, in which we report the detection of the C III ] λλ 1907,1909 nebular emission line. This represents the most distant detection of a metal transition, and the most distant redshift determination based on emission lines. In addition, we report tentative detections of [O II ] λλ 3726,3729 and [Ne III ] λ 3869, and possibly O III ] λλ 1661,1666. By using the accurate redshift obtained from C III ], we can model the Ly α drop to reliably measure an absorbing column density of hydrogen of N H I ≈ 10 22 cm −2 , which is too high for an IGM origin and implies an abundant neutral ISM in GS-z12 or in the CGM around it. We tentatively infer a lower limit for the neutral gas mass of about 10 7 M ⊙ which, compared with the galaxy stellar mass of ∼5 × 10 7 M ⊙ , implies a gas fraction higher than about 0.2–0.5. By comparing the measured emission lines with model-based diagnostic diagrams, we derive a solar or even super-solar carbon-to-oxygen ratio, tentatively log (C/O) > − 0.21 dex ([C/O] > 0.15 dex), while a Bayesian modelling of the spectrum indicates log (C/O) = − 0.30 ± 0.07 dex ([C/O] = 0.06 ± 0.07 dex). This is higher than the C/O measured in galaxies discovered by JWST at z = 6 − 9, and higher than the C/O arising from Type II supernovae enrichment. Asymptotic giant branch stars can hardly contribute to the observed carbon enrichment at these early epochs and low metallicities. Such a high C/O in a galaxy observed 350 Myr after the Big Bang may thus be explained by the yields of extremely metal-poor stars, and may even be the heritage of the first generation of supernovae from Population III progenitors. A robust determination of the total metallicity in this galaxy is essential to constrain these scenarios.

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Journal
Astronomy and Astrophysics
Published
2024-08-05
DOI
https://doi.org/10.1051/0004-6361/202348636
Citations
71
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
23.54

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JADES: Carbon enrichment 350 Myr after the Big Bang

Nimisha Kumari, Francesco D’Eugenio, Joris Witstok, Zhiyuan Ji et al.
71 citations
Astronomy and Astrophysics
Galaxies: Formation, Evolution, Phenomena
23.54
article

JADES: Carbon enrichment 350 Myr after the Big Bang

Nimisha Kumari, Francesco D’Eugenio, Joris Witstok, Zhiyuan Ji, Santiago Arribas, Fengwu Sun, R. Maiolino, Benjamin D. Johnson, Stefano Carniani, Kevin Hainline, Jacopo Chevallard, Sandro Tacchella, Chris J. Willott, S. Charlot, Mirko Curti, Tobias J. Looser, Daniel J. Eisenstein, Hannah Übler, Jan Scholtz, Erica J. Nelson, Emma Curtis-Lake, Christopher N. A. Willmer, William Baker, Kristan Boyett, Andrew J. Bunker, Brant E. Robertson, Marcia Rieke, Renske Smit, Giacomo Venturi, Kimihiko Nakajima
article en
71 citations

Abstract

Finding the emergence of the first metals in the early Universe and identifying their origin are some of the most important goals of modern astrophysics. We present deep JWST/NIRSpec spectroscopy of GS-z12, a galaxy at z = 12.5, in which we report the detection of the C III ] λλ 1907,1909 nebular emission line. This represents the most distant detection of a metal transition, and the most distant redshift determination based on emission lines. In addition, we report tentative detections of [O II ] λλ 3726,3729 and [Ne III ] λ 3869, and possibly O III ] λλ 1661,1666. By using the accurate redshift obtained from C III ], we can model the Ly α drop to reliably measure an absorbing column density of hydrogen of N H I ≈ 10 22 cm −2 , which is too high for an IGM origin and implies an abundant neutral ISM in GS-z12 or in the CGM around it. We tentatively infer a lower limit for the neutral gas mass of about 10 7 M ⊙ which, compared with the galaxy stellar mass of ∼5 × 10 7 M ⊙ , implies a gas fraction higher than about 0.2–0.5. By comparing the measured emission lines with model-based diagnostic diagrams, we derive a solar or even super-solar carbon-to-oxygen ratio, tentatively log (C/O) > − 0.21 dex ([C/O] > 0.15 dex), while a Bayesian modelling of the spectrum indicates log (C/O) = − 0.30 ± 0.07 dex ([C/O] = 0.06 ± 0.07 dex). This is higher than the C/O measured in galaxies discovered by JWST at z = 6 − 9, and higher than the C/O arising from Type II supernovae enrichment. Asymptotic giant branch stars can hardly contribute to the observed carbon enrichment at these early epochs and low metallicities. Such a high C/O in a galaxy observed 350 Myr after the Big Bang may thus be explained by the yields of extremely metal-poor stars, and may even be the heritage of the first generation of supernovae from Population III progenitors. A robust determination of the total metallicity in this galaxy is essential to constrain these scenarios.

Astronomy and AstrophysicsVol. 689
Herzberg Institute of Astrophysics (CA), Centre National de la Recherche Scientifique (FR), Space Telescope Science Institute (US), European Southern Observatory (DE), University of Arizona (US), University of Hertfordshire (GB), Scuola Normale Superiore (IT), The University of Melbourne (AU), University of California, Santa Cruz (US), University of Colorado Boulder (US), University of Cambridge (GB), Institut d'Astrophysique de Paris (FR), Sorbonne Université (FR), University of Oxford (GB), ASTRO-3D (AU), Center for Astrophysics Harvard & Smithsonian (US), Centro de Astrobiología (ES), ARC Centre of Excellence for All-sky Astrophysics (AU), National Astronomical Observatory of Japan (JP), University College London (GB), Liverpool John Moores University (GB)
Dell EMC, UK Research and Innovation, European Commission, Isaac Newton Trust, Ministerio de Ciencia e Innovación, Engineering and Physical Sciences Research Council, Science and Technology Facilities Council, Japan Society for the Promotion of Science, Agencia Estatal de Investigación
Openalex Percentile: Top 0%
Galaxies: Formation, Evolution, Phenomena
23.54
DOIOpen Access PDFOpenAlex
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