韩家信，上海交通大学天文系副教授。本科毕业于南京大学天文系，2013年在上海天文台获博士学位，随后在英国杜伦大学计算宇宙学研究所和日本Kavli IPMU进行博士后研究，并于2018年依托青千计划加入上海交通大学。主要研究方向是宇宙结构的形成与演化，尤其是暗物质分布的模拟、理论和观测。代表成果包括提出了暗物质晕的新边界——耗竭半径，并发展出新一代动态暗晕模型；开发了数值模拟中知名的子晕识别方法HBT，并发展起子晕的统一模型；开发了暗晕动力学建模的数据驱动方法oPDF并精确测得银河系质量等。Hierarchical structure formation predicts the existence of dark matter subhalos of different orders such as sub-subhalos and sub-sub-subhalos. Tidal stripping and mergers within these systems may be responsible for the formation of some of the most extreme galaxies in the universe, including dark matter deficient and ultra compact galaxies. Observationally, satellite groups corresponding to subhalo systems are also starting to get resolved. While universal laws governing the global subhalo population are relatively well-established, they often fail to distinguish between these subhalo orders, masking their hierarchical origins. In this talk, I will introduce an extremely simple yet powerful framework called "unbiased accretion" for establishing the laws of subhalo distribution across redshifts, cosmologies and subhalo levels. It naturally explains the bimodal fates of subhalos (disruption versus survival) and sheds light on the complex hierarchical mergers within the nested population. By extending the framework to the evolution of satellite galaxies, these results pave the way toward a new direction of "hierarchical archaeology", using satellite hierarchies as a powerful probe into the physics of dark matter and structure formation.