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Fe Abundances of Early Galaxies at $z=9-12$ Derived with Deep JWST Spectra by Nakane, Minami; Ouchi, Masami; Nakajima, Kimihiko; Ono, Yoshiaki; Harikane, Yuichi; Isobe, Yuki; Nomoto, Ken'ichi; Ishigaki, Miho N.; Yanagisawa, Hiroto; Kashino, Daichi; Tominaga, Nozomu; Takahashi, Koh; Nishigaki, Moka; Takeda, Yui; Watanabe, Kuria is a scholarly article available to read on EtoBox.

What is Fe Abundances of Early Galaxies at $z=9-12$ Derived with Deep JWST Spectra about?

We derive Fe-abundance ratios of 6 galaxies at $z=9-12$ with $-22<M_{\mathrm{UV}}<-19$ whose JWST/NIRSpec spectra achieve very high signal-to-noise ratios, $\mathrm{SNR}=40-230$, at the rest-frame UV wavelength. We fit stellar synthesis model spectra to these JWST spectra, carefully masking out nebular emission, interstellar absorption, and non-iron stellar absorption lines, and obtain Fe-abundance ratios of $\mathrm{[Fe/H]}=-2-0$ for 4 galaxies and upper limits of $\mathrm{[Fe/H]}\sim-1$ for 2 galaxies. We compare these [Fe/H] values with the oxygen abundances of these galaxies ($7.2<12+\log{\mathrm{(O/H)}}<7.9$) in the same manner as previous studies of low-$z$ galaxies, and derive oxygen-to-iron abundance ratios [O/Fe]. We find that majority of (4 out of 6) galaxies are consistent with iron-poor abundance ratios ($\mathrm{[O/Fe]}\gtrsim0$) while that 2 out of 6 galaxies, GS-z11-0 and GN-z11, show Fe enhancements ($\mathrm{[O/Fe]}<0$), especially GS-z11-0 ($z=11.12$) with a Fe enhancement ($\mathrm{[O/Fe]}=-0.91_{-0.42}^{+0.35}$) beyond the solar-abundance ratio at $\sim3\sigma$. Because, unlike GS-z11-0, GN-z11 ($z=10.60$) may be an AGN, we constrain [O/Fe] via FeII emission und

Author

Nakane, Minami; Ouchi, Masami; Nakajima, Kimihiko; Ono, Yoshiaki; Harikane, Yuichi; Isobe, Yuki; Nomoto, Ken'ichi; Ishigaki, Miho N.; Yanagisawa, Hiroto; Kashino, Daichi; Tominaga, Nozomu; Takahashi, Koh; Nishigaki, Moka; Takeda, Yui; Watanabe, Kuria

Published

2025

Language

EN