Title: Enhanced sub-resolution star formation models in cosmological simulations Show Chinese title

Title: 宇宙学模拟中增强的亚分辨率恒星形成模型

Abstract: One of the crucial components in simulating the growth and evolution of galaxies within a cosmological framework is the modeling of star formation (SF) and its corresponding feedback. Traditionally, the implemented SF law follows the empirical Kennicutt-Schmidt relation, which links the SF rate (SFR) in a gas element to the total gas density. More recently, an even stronger correlation has been observed between the SFR and the amount of molecular hydrogen ($\mathrm{H}_2$). This opens up the question of whether molecular hydrogen is a necessary precursor for SF or is instead a tracer of the total amount of gas, both of which would explain the observed correlations. In this study, we examine the impact of using an $\mathrm{H}_2$-based SF law on the formation of Milky Way-mass galaxies using cosmological, hydrodynamical simulations. We find that the galaxy modeled with our approach exhibits a well-defined, disc-like morphology. Compared to the traditional recipe, our model delays the onset of SF by approximately $500 \, \mathrm{Myr}$ resulting in a lower SFR, a smaller disc size, and a higher proportion of neutral to ionized gas within the disc region. These findings highlight the importance of including sophisticated SF models which can be compared to several observations -- including those related to $\mathrm{H}_2$ -- to better understand the processes affecting galaxy formation and evolution. Show Chinese abstract

Abstract: 在宇宙学框架内模拟星系生长与演化的一个关键组成部分是对恒星形成（SF）及其相应反馈的建模。 传统上，采用的恒星形成定律遵循经验性的Kennicutt-Schmidt关系，该关系将气体元素中的恒星形成率（SFR）与总气体密度联系起来。 最近，观察到恒星形成率与分子氢（$\mathrm{H}_2$）的数量之间存在更强的相关性。 这引发了关于分子氢是否是恒星形成的必要前兆，还是只是总气体量的示踪剂的疑问，这两种情况都可以解释所观察到的相关性。 在这项研究中，我们考察了基于$\mathrm{H}_2$的恒星形成定律对形成类似银河系质量星系的影响，使用的是宇宙学、流体动力学模拟。 我们发现，用我们的方法建模的星系表现出明确的盘状形态。 与传统的配方相比，我们的模型将恒星形成的开始时间推迟了大约$500 \, \mathrm{Myr}$，导致较低的恒星形成率、较小的盘尺寸以及盘区域内中性气体与电离气体的比例更高。 这些发现突显了包括复杂恒星形成模型的重要性，这些模型可以与多种观测结果进行比较——包括与$\mathrm{H}_2$相关的观测结果——以更好地理解影响星系形成和演化的机制。