A First Look at the Abundance Pattern—O/H, C/O, and Ne/O—in z > 7 Galaxies with JWST/NIRSpec
Karla Z. Arellano-Córdova, Danielle A. Berg, John Chisholm, Pablo Arrabal Haro, Mark Dickinson, Steven L. Finkelstein, Floriane Leclercq, Noah S. J. Rogers, Raymond C. Simons, Evan D. Skillman, Jonathan R. Trump, Jeyhan S. Kartaltepe
Abstract
Abstract We analyze the rest-frame near-UV and optical nebular spectra of three z > 7 galaxies from the Early Release Observations taken with the Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope (JWST). These three high- z galaxies show the detection of several strong emission nebular lines, including the temperature-sensitive [O iii ] λ 4363 line, allowing us to directly determine the nebular conditions and abundances for O/H, C/O, and Ne/O. We derive O/H abundances and ionization parameters that are generally consistent with other recent analyses. We analyze the mass–metallicity relationship (i.e., slope) and its redshift evolution by comparing between the three z > 7 galaxies and local star-forming galaxies. We also detect the C iii ] λλ 1907, 1909 emission in a z > 8 galaxy from which we determine the most distant C/O abundance to date. This valuable detection of log(C/O) = −0.83 ± 0.38 provides the first test of C/O redshift evolution out to high redshift. For neon, we use the high-ionization [Ne iii ] λ 3869 line to measure the first Ne/O abundances at z > 7, finding no evolution in this α -element ratio. We explore the tentative detection of [Fe ii ] and [Fe iii ] lines in a z > 8 galaxy, which would indicate a rapid buildup of metals. Importantly, we demonstrate that properly flux-calibrated and higher-S/N spectra are crucial to robustly determine the abundance pattern in z > 7 galaxies with NIRSpec/JWST.