宇宙黎明时期的明亮星系：一个统一可变恒星形成效率、初始质量函数和随机性的云尺度恒星形成模型
Bright Galaxies at Cosmic Dawn: A Cloud-Scale Star Formation Model Unifying Variable SFE, IMFs, and Stochasticity
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中文总结 AI 辅助
研究红移z>10时紫外明亮星系起源，提出新半解析模型，通过追踪恒星形成云弥合小尺度与大尺度差距，捕捉随机性，确定三种恒星形成模式，揭示模型成分对紫外光度函数的影响，表明云尺度物理塑造早期星系紫外光度分布。
中文摘要 AI 辅助
为了研究红移z > 10时大量紫外明亮星系的起源，我们提出了一个新的半解析模型，通过在平滑演化的暗物质势中明确追踪离散的恒星形成云，弥合了小尺度恒星形成物理和大尺度星系演化之间的差距。与传统半解析模型不同，我们的方法自然地捕捉了恒星形成的随机性，使我们能够分离出云属性、恒星形成效率（SFE）和恒星初始质量函数（IMF）如何塑造早期星系的恒星形成爆发性。云从云质量分布中依次抽取，根据云质量、金属丰度和红移分配一个SFE和IMF，并在短时间尺度恒星反馈的影响下演化。我们确定了由云质量、密度和反馈时间尺度之间的相互作用产生的三种不同的恒星形成模式：低质量晕中具有长静止阶段的随机、反馈受限模式；由云质量分布调节的爆发模式；以及大质量晕中的平滑、连续模式。我们的基准模型采用动态IMF、与云属性和IMF相关的SFE以及大质量、中等密度的云。改变假设表明，大质量云中的重顶IMF和增强的SFE会放大爆发性，而改变云质量上限或密度归一化则是次要的。在模型成分中，IMF对紫外光度函数（LF）影响最大，而切换到恒定SFE会提高暗端，降低最大云质量会降低亮端。这些结果表明，云尺度物理对早期星系紫外光度分布起着关键作用。
英文摘要
To investigate the origins of the high abundance of UV-bright galaxies at z > 10, we present a new semi-analytic model that bridges the gap between small-scale star formation physics and large-scale galaxy evolution by explicitly tracking discrete star-forming clouds within smoothly evolving dark matter potentials. Unlike conventional semi-analytic models, our approach naturally captures the stochasticity of star formation, allowing us to isolate how cloud properties, star formation efficiencies (SFEs), and stellar initial mass functions (IMFs) shape the star-formation burstiness of early galaxies. Clouds are drawn sequentially from a cloud mass distribution, assigned an SFE and IMF depending on cloud mass, metallicity, and redshift, and evolve under the influence of short-timescale stellar feedback. We identify three distinct star formation regimes arising from the interplay between cloud masses, densities, and feedback timescales: a stochastic, feedback-limited regime in low-mass halos with long quiescent phases; a bursty regime regulated by the cloud mass distribution; and a smooth, continuous regime in massive halos. Our fiducial model adopts a dynamic IMF, an SFE linked to cloud properties and the IMF, and massive, moderately dense clouds. Varying assumptions reveals that top-heavy IMFs and enhanced SFEs in massive clouds amplify burstiness, while altering the upper cloud mass or density normalisation is secondary. Among model ingredients, the IMF most strongly impacts the UV luminosity function (LF), while switching to a constant SFE boosts the faint end, and reducing the maximum cloud mass decreases the bright end. These results demonstrate that cloud-scale physics critically shape early galaxy UV luminosity distributions.
