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D’Eugenio, F, Maiolino, R, Carniani, S, Chevallard, J, Curtis-Lake, E, Witstok, J, Charlot, S, Baker, WM, Arribas, S, Boyett, K, Bunker, AJ, Curti, M, Eisenstein, DJ, Hainline, K, Ji, Z, Johnson, BD, Kumari, N, Looser, TJ, Nakajima, K, Nelson, E , Rieke, M, Robertson, B, Scholtz, J, Smit, R, Sun, F, Venturi, G, Tacchella, S, Übler, H, Willmer, CNA and Willott, C (2024) JADES: Carbon enrichment 350 Myr after the Big Bang. Astronomy and Astrophysics, 689. pp. 1-16. ISSN 0004-6361
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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]λλ1907,1909 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]λλ3726,3729 and [Ne iii]λ3869, and possibly O iii]λλ1661,1666. By using the accurate redshift obtained from C iii], we can model the Lyα drop to reliably measure an absorbing column density of hydrogen of NHi ≈ 1022 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 107 M which, compared with the galaxy stellar mass of ∼5 × 107 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.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | 0201 Astronomical and Space Sciences; Astronomy & Astrophysics |
| Subjects: | Q Science > QB Astronomy Q Science > QC Physics |
| Divisions: | Astrophysics Research Institute |
| Publisher: | EDP Sciences |
| SWORD Depositor: | A Symplectic |
| Date Deposited: | 08 Oct 2024 16:21 |
| Last Modified: | 08 Oct 2024 16:30 |
| DOI or ID number: | 10.1051/0004-6361/202348636 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/24464 |
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