Abstract
Abstract
The abundance of carbon relative to oxygen (C/O) is a promising probe of star formation history in the early universe, as the ratio changes with time due to production of these elements by different nucleosynthesis pathways. We present a measurement of
log
(
C
/
O
)
=
−
1.01
±
0.12
(stat) ±0.15 (sys) in a z = 6.23 galaxy observed as part of the GLASS–JWST Early Release Science Program. Notably, we achieve good precision thanks to the detection of the rest-frame ultraviolet O iii], C iii], and C iv emission lines delivered by JWST/NIRSpec. The C/O abundance is ∼0.8 dex lower than the solar value and is consistent with the expected yield from core-collapse supernovae, indicating that longer-lived intermediate-mass stars have not fully contributed to carbon enrichment. This in turn implies rapid buildup of a young stellar population with age ≲100 Myr in a galaxy seen ∼900 Myr after the big bang. Our chemical abundance analysis is consistent with spectral energy distribution modeling of JWST/NIRCam photometric data, which indicates a current stellar mass
log
M
*
/
M
☉
=
8.4
−
0.2
+
0.4
and specific star formation rate ≃20 Gyr−1. These results showcase the value of chemical abundances and C/O in particular to study the earliest stages of galaxy assembly.
Funder
Space Telescope Science Institute
Istituto Nazionale di Astrofisica
Chinese Academy of Sciences
Javna Agencija za Raziskovalno Dejavnost RS
Department of Education and Training ∣ Australian Research Council
Danmarks Grundforskningsfond
Publisher
American Astronomical Society
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
17 articles.
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