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arXiv 1102.5736astro-ph.CO
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暗物质晕的总质量

The Total Mass of Dark Matter Haloes

Donnino Anderhalden, Juerg Diemand

摘要:

宇宙学模拟中常用的简单传统的暗物质晕质量定义(“维里”质量,FoF质量,$M_{50,100,200,...}$)只捕获了部分坍缩物质,因此与结构形成的分析处理中使用的晕质量概念不一致。模拟表明,典型的暗物质粒子轨道延伸到其转向半径的90%左右,这导致在第一轨道和第二轨道上的远心通道超出当前的“维里”半径。在这里,我们描述了如何形成的历史晕可以用来识别那些粒子参加了晕崩溃,但错过了传统的组查找器,因为他们的远程目前的位置。这些粒子被添加到已经由FoF识别的晕的部分。暗晕的校正质量显着更高(中位数质量增加25%),有一个相当大的转变的光环质量函数向新闻和Schechter形式。我们的结论是,有意义的定量比较(半)分析预测晕属性(如质量函数,质量吸积率,合并率,空间集群等)。并且模拟结果将需要在两种方法中使用相同的晕圈定义。

英文摘要:

The simple, conventional dark matter halo mass definitions commonly used in cosmological simulations ("virial" mass, FoF mass, $M_{50,100,200,...}$) only capture part of the collapsed material and are therefore inconsistent with the halo mass concept used in analytical treatments of structure formation. Simulations have demonstrated that typical dark matter particle orbits extend out to about 90 per cent of their turnaround radius, which results in apocenter passages outside of the current "virial" radius on the first and also on the second orbit. Here we describe how the formation history of haloes can be used to identify those particles which took part in the halo collapse, but are missed by conventional group-finders because of their remote present location. These particles are added to the part of the halo already identified by FoF. The corrected masses of dark haloes are significantly higher (the median mass increase is 25 per cent) and there is a considerable shift of the halo mass function towards the Press & Schechter form. We conclude that meaningful quantitative comparisons between (semi-)analytic predictions of halo properties (e.g. mass functions, mass accretion rates, merger rates, spatial clustering, etc.) and simulation results will require using the same halo definition in both approaches.

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