We present an [O/Fe] ratio of a luminous galaxy GN-z11 at z = 10.60 derived with the deep public JWST/NIRSpec data. We fit the medium-resolution grating (G140M, G235M, and G395M) data with the model spectra consisting of BPASS-stellar and Cloudy-nebular spectra in the rest-frame UV wavelength ranges with Fe absorption lines, carefully masking the other emission and absorption lines in the same manner as previous studies conducted for lower-redshift (z ∼ 2–6) galaxies with oxygen abundance measurements. We obtain an Fe-rich abundance ratio , which is confirmed with the independent deep prism data as well as by the classic 1978 index method. This [O/Fe] measurement is lower than that measured for star-forming galaxies at z ∼ 2–3. Because z = 10.60 is an early epoch after the Big Bang (∼430 Myr) and the first star formation (likely ∼200 Myr), it is difficult to produce Fe by Type Ia supernovae (SNe Ia), which requires sufficient delay time for white-dwarf formation and gas accretion. The Fe-rich abundance ratio in GN-z11 suggests that the delay time is short or that the major Fe enrichment is not accomplished by SNe Ia but by bright hypernovae (BrHNe) and/or pair-instability supernovae (PISNe), where the yield models of BrHNe and PISNe explain Fe, Ne, and O abundance ratios of GN-z11. The [O/Fe] measurement is not too low to rule out the connection between GN-z11 and globular clusters (GCs) previously suggested by the nitrogen abundance but rather supports the connection with a GC population at high [N/O] if a metal dilution process exists.

中文翻译：

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宇宙纪元早期发光星系中的低 [O/Fe] 比值 （z > 10）：短延迟时间的特征还是明亮的超新星/对不稳定的超新星？


我们提出了一个发光星系 GN-z11 在 z = 10.60 时的 [O/Fe] 比率，该比率是由深度公共 JWST/NIRSpec 数据得出的。我们将中分辨率光栅（G140M、G235M 和 G395M）数据与由静止框架紫外波长范围内的 BPASS 恒星和云星云光谱组成的模型光谱与 Fe 吸收线进行拟合，小心地掩盖其他发射和吸收线，就像以前对低红移 （z ∼ 2-6） 星系进行的研究一样，进行氧丰度测量。我们得到了一个富铁丰度比，这可以通过独立的深棱柱数据以及经典的 1978 指数方法得到证实。这个 [O/Fe] 测量值低于 z ∼ 2-3 处恒星形成星系的测量值。因为 z = 10.60 是大爆炸 （∼430 Myr） 和第一次恒星形成 （可能 ∼200 Myr） 之后的早期纪元，所以很难通过 Ia 型超新星 （SNe Ia） 产生 Fe，这需要足够的延迟时间来形成白矮星和气体吸积。GN-z11 中富含 Fe 的丰度比表明延迟时间短，或者主要的 Fe 富集不是由 SNe Ia 完成的，而是由亮超新星 （BrHNe） 和/或成对不稳定超新星 （PISNe） 完成的，其中 BrHNe 和 PISNe 的产率模型解释了 GN-z11 的 Fe、Ne 和 O 丰度比。[O/Fe] 测量值并不太低，无法排除 GN-z11 与之前由氮丰度所暗示的球状团簇 （GC） 之间的联系，但如果存在金属稀释过程，则支持与高 [N/O] 的 GC 群有关。