Linear and non-linear contributions to pairwise peculiar velocities
Linear and non-linear contributions to pairwise peculiar velocities
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DOI：
10.1046/j.1365-8711.2001.04222.x
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发表时间：
2000-09
影响因子：
4.8
通讯作者：
R. Sheth;L. Hui;Antonaldo Diaferio Roman Scoccimarro
中科院分区：
文献类型：
--
作者：
R. Sheth;L. Hui;Antonaldo Diaferio Roman Scoccimarro
我们将暗物质粒子的关联函数ξ(R)写成两个项的总和--一个解释非线性演化，并在小尺度上起主导作用，另一个本质上是来自线性理论的项，在大尺度上起主导作用。我们使用晕数和晕密度分布的模型来描述非线性项及其演化。这一结果很好地描述了ξ(R)在模拟中的演化过程。然后，我们使用这种分解来提供简单而准确的模型，说明单粒子速度色散如何随时间演变，以及成对速度分布的一阶矩和二阶矩如何依赖于尺度。其核心思想是使用大尺度上的线性理论的简单物理、小尺度上的维里定理的简单物理以及我们的关联函数模型来告诉我们如何对成对速度统计的两种贡献(线性和非线性)进行加权。当结合到流动模型中时，我们的结果将允许简单准确地描述整个线性到高度非线性区域的红移空间扭曲。
We write the correlation function of dark matter particles, ξ(r), as the sum of two terms – one which accounts for non-linear evolution, and dominates on small scales, and another which is essentially the term from linear theory, and dominates on large scales. We use models of the number and spatial distribution of haloes and halo density profiles to describe the non-linear term and its evolution. The result provides a good description of the evolution of ξ(r) in simulations. We then use this decomposition to provide simple and accurate models of how the single-particle velocity dispersion evolves with time, and how the first and second moments of the pairwise velocity distribution depend on scale. The key idea is to use the simple physics of linear theory on large scales, the simple physics of the virial theorem on small scales and our model for the correlation function to tell us how to weight the two types of contributions (linear and non-linear) to the pairwise velocity statistics. When incorporated into the streaming model, our results will allow a simple accurate description of redshift-space distortions over the entire range of linear to highly non-linear regimes.