发表机构
Kyung Hee University; NSF National Optical-Infrared Astronomy Research Laboratory; Space Telescope Science Institute（庆熙大学; 美国国家光学-红外天文研究实验室; 太空望远镜科学研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过高分辨率模拟对比均匀与斑块状再电离模型，发现后者平均延迟超微暗弱矮星系恒星形成终止约4.4亿年，但未显著影响金属丰度，强调需采用更真实的再电离模型解释本地群星系多样性。
AI 中文摘要
宇宙再电离的空间不均匀性直接编码在超微暗弱矮星系（UFDs）的恒星形成终止时标中。尽管大多数宇宙学模拟出于计算效率考虑采用空间均匀的紫外背景（UVB），但这种均匀处理可能过度简化了再电离对UFDs的物理影响，因为UFDs的恒星形成历史（SFHs）对局部环境高度敏感。在这些理想化的、瞬时的UVB框架下，UFDs中的恒星形成通常在再电离开始时被突然截断，这与在本地群UFDs中观测到的延长且多样的SFHs产生矛盾。为了解决这一差异，我们进行了高分辨率的宇宙学zoom-in模拟，以对比两种不同的再电离模型：传统的均匀UVB和基于实时辐射转移（RT）的斑块状再电离模型。我们发现，基于RT的再电离平均延迟了恒星形成终止约440百万年，这一结果与最近的观测约束一致。然而，这种延长的恒星形成并不一定在恒星金属丰度分布上留下可辨别的印记，表明这种延迟——虽然对气体动力学在物理上具有重要意义——仍不足以驱动显著的化学增丰。我们的结果强调了采用更真实的斑块状再电离建模来解释观测到的本地群星系种群多样性的必要性。
英文摘要
The spatially inhomogeneous nature of cosmic reionization is directly encoded in the quenching timescales of ultra-faint dwarf galaxies (UFDs). While most cosmological simulations employ a spatially uniform UV background (UVB) for computational efficiency, such homogeneous treatment may oversimplify the physical impact of reionization on UFDs, whose star formation histories (SFHs) are highly sensitive to local environments. Under these idealized, instantaneous UVB frameworks, star formation in UFDs is typically truncated abruptly at the onset of reionization, creating a tension with the extended and diverse SFHs observed in Local Group UFDs. To address this discrepancy, we perform high-resolution cosmological zoom-in simulations to contrast two distinct reionization models: a conventional uniform UVB and an on-the-fly radiative transfer (RT)-based patchy reionization model. We find that RT-based reionization delays star-formation quenching by ~440 Myr on average, a result consistent with recent observational constraints. However, this extended star formation does not necessarily leave a discernible imprint on the stellar metallicity distribution, indicating that the delay--while physically significant for gas dynamics--is still insufficient to drive substantial chemical enrichment. Our results emphasize the necessity of more realistic, patchy reionization modeling to explain the observed diversity of the Local Group population.
CommentsAccepted for publication in ApJ. 27 pages, 16 figures
