Halo Assembly Bias in Hierarchical Structure Formation
Halo Assembly Bias in Hierarchical Structure Formation
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DOI：
10.1086/591512
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发表时间：
2008-03
期刊：
影响因子：
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通讯作者：
N. Dalal;M. White;J. Bond;A. Shirokov
中科院分区：
文献类型：
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作者：
N. Dalal;M. White;J. Bond;A. Shirokov
我们研究晕组装偏差的起源，即晕聚类对组装历史的依赖性。我们将晕组装与在初始线性高斯随机密度场的拉格朗日空间中测量的峰值特性相关联，并展示这些相同的拉格朗日特性如何决定大尺度偏差。我们关注已观察到组装偏差显著的两种情况：与非线性质量尺度相比，质量非常大以及非常小的情况。在高质量端，我们表明从高斯随机涨落峰值的统计数据中可以预期组装偏差，并且我们表明在罕见晕的N体模拟中发现的组装偏差程度与我们的理论预测非常吻合。在低质量端，我们认为组装偏差主要源于一小部分质量吸积已经停止的低质量晕。由于它们的发展停滞，这些晕自然变得无偏差，这与它们有偏差的同类晕形成对比。我们表明一个包含这些效应的简单玩具模型可以大致重现N体模拟中发现的偏差趋势。
We investigate the origin of halo assembly bias, the dependence of halo clustering on assembly history. We relate halo assembly to peak properties measured in the Lagrangian space of the initial linear Gaussian random density field and show how these same Lagrangian properties determine large-scale bias. We focus on the two regimes where assembly bias has been observed to be significant: at masses very large and very small compared to the nonlinear mass scale. At high masses, we show that assembly bias is expected from the statistics of the peaks of Gaussian random fluctuations, and we show that the extent of assembly bias found in N-body simulations of rare halos is in excellent agreement with our theoretical prediction. At low masses, we argue that assembly bias largely arises from a subpopulation of low-mass halos whose mass accretion has ceased. Due to their arrested development, these halos naturally become unbiased, in contrast to their antibiased peers. We show that a simple toy model incorporating these effects can roughly reproduce the bias trends found in N-body simulations.