EMPRESS. XIII. Chemical Enrichments of Young Galaxies Near and Far at z ~ 0 and 4-10: Fe/O, Ar/O, S/O, and N/O Measurements with Chemical Evolution Model Comparisons

We present gas-phase elemental abundance ratios of 7 local extremely metal-poor galaxies (EMPGs) including our new Keck/LRIS spectroscopy determinations together with 33 JWST $z\sim 4-10$ star-forming galaxies in the literature, and compare chemical evolution models. We develop chemical evolution models with the yields of core-collapse supernovae (CCSNe), Type Ia supernovae, hypernovae (HNe), and pair-instability supernovae (PISNe), and compare the EMPGs and high-$z$ galaxies in conjunction with dust depletion contributions. We find that high Fe/O values of EMPGs can (cannot) be explained by PISN metal enrichments (CCSN/HN enrichments even with the mixing-and-fallback mechanism enhancing iron abundance), while that the observed Ar/O and S/O values are much smaller than the predictions of the PISN models. The abundance ratios of the EMPGs can be explained by the combination of Type Ia SNe and CCSNe/HNe whose inner layers of argon and sulfur mostly fallback, which are comparable with Sculptor stellar chemical abundance distribution, suggesting that early chemical enrichment is taken place in the EMPGs. Comparing our chemical evolution models with the star-forming galaxies at $z\sim 4-10$, we find that the Ar/O and S/O ratios of the high-$z$ galaxies are comparable with those of the CCSNe/HNe models, while majority of the high-$z$ galaxies do not have constraints good enough to rule out contributions from PISNe. The high N/O ratio recently reported in GN-z11 cannot be explained even by rotating PISNe, but could be reproduced by the winds of rotating Wolf Rayet stars that end up as a direct collapse

EMPRESS. IV. Extremely Metal-poor Galaxies Including Very Low-mass Primordial Systems with M <SUB>*</SUB> = 10<SUP>4</SUP>-10<SUP>5</SUP> M <SUB>⊙</SUB> and 2%-3% (O/H): High (Fe/O) Suggestive of Metal Enrichment by Hypernovae/Pair-instability Supernovae

International audienceWe present Keck/LRIS follow-up spectroscopy for 13 photometric candidates of extremely metal-poor galaxies (EMPGs) selected by a machine-learning technique applied to the deep (~26 AB mag) optical and wide-area (~500 deg2) Subaru imaging data in the EMPRESS survey. Nine out of the 13 candidates are EMPGs with an oxygen abundance (O/H) less than ~10% solar value (O/H)⊙, and four sources are contaminants of moderately metal-rich galaxies or no emission-line objects. Notably, two out of the nine EMPGs have extremely low stellar masses and oxygen abundances of 5 × 104-7 × 105 M ⊙ and 2%-3% (O/H)⊙, respectively. With a sample of five EMPGs with (Fe/O) measurements, two (three) of which are taken from this study (the literature), we confirm that two EMPGs with the lowest (O/H) ratios of ~2% (O/H)⊙ show high (Fe/O) ratios of ~0.1, close to the solar abundance ratio. Comparing galaxy chemical enrichment models, we find that the two EMPGs cannot be explained by a scenario of metal-poor gas accretion/episodic star formation history due to their low (N/O) ratios. We conclude that the two EMPGs can be reproduced by the inclusion of bright hypernovae and/or hypothetical pair-instability supernovae (SNe) preferentially produced in a metal-poor environment. This conclusion implies that primordial galaxies at z ~ 10 could have a high abundance of Fe that did not originate from Type Ia SNe with delays and that Fe may not serve as a cosmic clock for primordial galaxies