暗物质晕的边界研究进展
介绍了关于暗物质晕的边界定义问题。传统的球形高密算法，将一定密度的球形高密度区定义为一个暗晕，该定义方式会出现“伪演化”的问题。早期寻找暗晕的算法还包括常用的连接邻近粒子的“朋友链”算法。此外也进行过各种探索，如：根据静态区间的最远位置而定义的暗晕静态半径，以及近些年根据密度轮廓在外围剧烈下降这一特点而提出的回溅半径、根据暗晕的动力学特征所提出的特征耗竭半径和内部耗竭半径，这些定义能够反映暗晕的动态特性。同时还介绍了计算回溅半径的两种程序和观测支持，以及对于银河系的内部耗竭半径的探测。对暗晕的并合树以及增长过程也进行了介绍。最后对各种边界进行总结和展望。
天文学
暗物质晕边界高密度回溅半径耗竭半径
宋家宇1,2.暗物质晕的边界研究进展[EB/OL].(2023-06-07)[2025-09-22].https://chinaxiv.org/abs/202306.00403.点此复制
Dark matter haloes, whose boundary definition is controversial for a long time, are the building blocks of our universe. We review the explorations of this issue. Traditionally, the spherical overdensity definition, which defines a dense enough spherical region as a halo, can lead to the problem of pseudo-evolution. That is, according to its definition, a halos mass and radius grow many times but without much happened in its inner structure and physical processes. Another common method is the famous friends-of-friends algorithm, which links particles nearby. Both of these two algorithms are early and classical methods, which are fast to run but have little physical meanings. Besides, new methods can always been put forward. The static radius, which is defined at the outermost location of the static region, has been introduced. The splashback radius, is proposed because of the discovery that the logarithmic slope of the density profile of haloes decreases steeply at outer region. We then introduce two algorithms to calculate the splashback radius and show some observational evidence of it. The inner depletion radius and characteristic depletion radius are defined based on halos dynamical properties, the former has been measured through our Milky Way. Theres also some connection between splashback radius and inner depletion radius, the latter could be regarded as the outermost splashback boundary. We also introduce the merger tree and accretion history of dark matter haloes. Finally, we summarize different kinds of boundaries and show some prospects.
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