解释高红移星系中观测到的高氮丰度：通过数千太阳质量的第三族恒星
Explaining the high nitrogen abundances observed in high-z galaxies via population III stars of a few thousand solar masses
AI总结：
本研究通过辐射流体动力学模拟和恒星演化建模，发现质量在2000至9000太阳质量间的第一代第三族恒星能解释高红移星系GN-z11和CEERS 1019中观测到的氮氧等元素丰度，揭示了极端大质量第三族恒星在早期宇宙化学增丰中的关键作用。
摘要：
早期宇宙的化学增丰是星系形成和演化的关键要素，而第三族（PopIII）恒星在这一过程中必定扮演着至关重要的角色。在本研究中，我们考察了早期宇宙胚胎星系中大质量恒星产生的金属增丰。利用辐射流体动力学模拟和恒星演化建模，我们计算了这些恒星预期的金属产量。具体而言，我们采用了先前辐射流体动力学模拟中的吸积率来指导我们的恒星演化建模，该建模使用日内瓦代码执行，覆盖了11个选定的数据集，最终恒星质量在500至9000太阳质量之间。我们的结果表明，质量范围在2000至9000太阳质量之间的第一代第三族恒星所产生的N/O、C/O和O/H比值与在极高红移星系GN-z11和CEERS 1019中观测到的数值相符。这些第三族恒星的喷出物主要由He、H和N组成。我们针对晕的第三族化学增丰模型能够精确再现观测到的N/O和C/O比值，并且通过将恒星喷出物与百倍于其质量的零金属度星际物质混合，该模型精确达到了观测到的O/H比值。因此，一个质量超过约2000太阳质量的极端大质量第三族恒星亚群，能够有效再现迄今为止在高红移JWST星系中观测到的CNO元素丰度。
英文摘要：
The chemical enrichment of the early Universe is a crucial element in the formation and evolution of galaxies, and Population III (PopIII) stars must play a vital role in this process. In this study, we examine metal enrichment from massive stars in the early Universe's embryonic galaxies. Using radiation hydrodynamic simulations and stellar evolution modelling, we calculated the expected metal yield from these stars. Specifically, we applied accretion rates from a previous radiation-hydrodynamic simulation to inform our stellar evolution modelling, executed with the Geneva code, across 11 selected datasets, with final stellar masses between 500 and 9000 Msol. Our results demonstrate that the first generation of Pop III stars within a mass range of 2000 to 9000 Msol result in N/O, C/O and O/H ratios compatible with the values observed in very high-z galaxies GN-z11 and CEERS 1019. The ejecta of these Pop III stars are predominantly composed of He, H, and N. Our Pop III chemical enrichment model of the halo can accurately reproduce the observed N/O and C/O ratios, and, by incorporating a hundred times more zero-metallicity interstellar material with the stellar ejecta, it accurately attains the observed O/H ratio. Thus, a sub-population of extremely massive PopIII stars, with masses surpassing approximately 2000 Msol, effectively reproduces the CNO elemental abundances observed in high-z JWST galaxies to date.
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