JWST Identification of Extremely Low C/N Galaxies with [N/O] at Evidencing the Early CNO-Cycle Enrichment and a Connection with Globular Cluster�…

Y Isobe, M Ouchi, N Tominaga, K Watanabe…�- arXiv preprint arXiv�…, 2023 - arxiv.org
Y Isobe, M Ouchi, N Tominaga, K Watanabe, K Nakajima, H Umeda, H Yajima, Y Harikane
arXiv preprint arXiv:2307.00710, 2023arxiv.org
We present chemical abundance ratios of 70 star-forming galaxies at $ z\sim4 $-10
observed by the JWST/NIRSpec ERO, GLASS, and CEERS programs. Among the 70
galaxies, we have pinpointed 2 galaxies, CEERS_01019 at $ z= 8.68$ and GLASS_150008
at $ z= 6.23$, with extremely low C/N ([C/N] $\lesssim-1$), evidenced with CIII]
$\lambda\lambda $1907, 1909, NIII] $\lambda $1750, and NIV] $\lambda\lambda $1483,
1486, which show high N/O ratios ([N/O] $\gtrsim 0.5$) comparable with the one of GN-z11�…
We present chemical abundance ratios of 70 star-forming galaxies at -10 observed by the JWST/NIRSpec ERO, GLASS, and CEERS programs. Among the 70 galaxies, we have pinpointed 2 galaxies, CEERS_01019 at and GLASS_150008 at , with extremely low C/N ([C/N]), evidenced with CIII]1907,1909, NIII]1750, and NIV]1483,1486, which show high N/O ratios ([N/O]) comparable with the one of GN-z11. CEERS_01019 (GLASS_150008) has (does not have) a strong high ionization line that is explained by AGN (star-formation) photoionization models, which is (not) similar to GN-z11. Such low C/N and high N/O ratios found in CEERS_01019 and GLASS_150008 (additionally identified in GN-z11) are close to the equilibrium of the CNO cycle, suggesting that these 3 galaxies are enriched by metals processed by the CNO cycle. On the C/N vs. O/H plane, these 3 galaxies do not coincide with Galactic HII regions, normal star-forming galaxies, and nitrogen-loud quasars with AGB stars, but globular-cluster (GC) stars, indicating a connection with GC formation. We compare C/O and N/O of these 3 galaxies with those of theoretical models, and find that these 3 galaxies are explained by scenarios with dominant CNO-cycle materials, i.e. Wolf-Rayet stars, supermassive () stars, and tidal disruption events, interestingly with a requirement of frequent direct collapses. For all the 70 galaxies, we present measurements of Ne/O, S/O, and Ar/O, together with C/O and N/O. We identify 4 galaxies with very low Ne/O, , indicating abundant massive () stars.
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