为什么人为瓦解不是当前宇宙学模拟需要担忧的问题
Why artificial disruption is not a concern for current cosmological simulations
AI总结：
本文基于Aquarius模拟发现子晕存活与瓦解对应两种吸积通道，证明高红移子-子晕的快速消失源于物理性高质量损失率而非数值效应，表明当前宇宙学模拟已可靠分辨子晕群体。
摘要：
近期研究表明，冷暗物质子晕很难被瓦解，数值模拟中观察到的几乎所有子晕瓦解事例都是由数值效应造成的。然而，这些发现主要依赖于理想化数值实验，并不能完全反映等级式宇宙学背景下子晕演化的真实条件。基于Aquarius模拟，我们在存活子晕与瓦解子晕群体中识别出明显的分离现象，这种分离对应着两种不同的子晕吸积通道。我们发现，红移2之后吸积的所有一阶子晕都存活至今，没有遭受人为瓦解。另一方面，大多数瓦解的子晕是在高红移处被吸积的子-子晕。与一阶子晕不同，子-子晕经历了预处理，其中许多是通过高红移处的主并合被吸积的，从而导致非常高的质量损失率。我们通过数值实验和半解析模型确认这些高质量损失率是物理性的，从而支持它们在模拟中快速消失具有物理起源。尽管我们无法验证这些子晕是否已完全瓦解，但它们极端的质量损失率表明，它们至多只能对子晕质量函数极低质量端贡献一个可忽略的比例。因此我们得出结论：当前最先进的宇宙学模拟已经可靠地分辨了子晕群体。
英文摘要：
Recent studies suggest that cold dark matter subhalos are hard to disrupt and almost all cases of subhalo disruption observed in numerical simulations are due to numerical effects. However, these findings primarily relied on idealized numerical experiments, which do not fully capture the realistic conditions of subhalo evolution within a hierarchical cosmological context. Based on the Aquarius simulations, we identify clear segregation in the population of surviving and disrupted subhalos, which corresponds to two distinct acquisition channels of subhalos. We find that all of the first-order subhalos accreted after redshift 2 survive to the present time without suffering from artificial disruption. On the other hand, most of the disrupted subhalos are sub-subhalos accreted at high redshift. Unlike the first-order subhalos, sub-subhalos experience pre-processing and many of them are accreted through major mergers at high redshift, resulting in very high mass loss rates. We confirm these high mass loss rates are physical through both numerical experiments and semi-analytical modeling, thus supporting a physical origin for their rapid disappearance in the simulation. Even though we cannot verify whether these subhalos have fully disrupted or not, their extreme mass loss rates dictate that they can at most contribute a negligible fraction to the very low mass end of the subhalo mass function. We thus conclude that current state-of-the-art cosmological simulations have reliably resolved the subhalo population.
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