论文标题
位置依赖性伏诺元的概率分布功能和光晕
Position-dependent Voronoi probability distribution functions for matter and halos
论文作者
论文摘要
我们测量了N体模拟中暗物质和光晕的Voronoi密度概率分布函数（PDF）。对于暗物质，Voronoi密度代表物质密度在均匀的质量尺度上平滑的物质密度场，这近似于Lagrangian密度场。对于Halos，Voronoi密度包含有关每个光晕的局部环境的信息。我们测量了光环病毒质量，每个光环伏罗尼元细胞中的暗物质总量以及晕旋voronoi细胞体积，我们显示了光晕丰度如何依赖于这三个量。然后，我们使用单独的宇宙模拟研究了在宇宙有限的子区域内测量的位置依赖性伏诺密度PDF。我们证明了依赖位置的PDF的空间变化是由于大规模密度波动引起的，表明依赖位置的PDF是大规模结构的有偏见的示踪剂。我们测量了暗物质的这种偏见，并将其解释为基于密度选择的拉格朗日密度场区域的偏见。对于光环，这种偏见可以解释为一种组装偏见的一种形式。我们为每个模拟暗物质粒子介绍了从较晚到早期的伏诺密度的映射，这是高度随机的。我们将该随机图的中值与球形崩溃计算进行了比较，并讨论了在这些尺度上建模密度场演变所涉及的挑战。
We measure the Voronoi density probability distribution function (PDF) for both dark matter and halos in N-body simulations. For the dark matter, Voronoi densities represent the matter density field smoothed on a uniform mass scale, which approximates the Lagrangian density field. For halos, the Voronoi densities contain information about the local environment of each halo. We measure the halo virial masses, the total amount of dark matter within each halo Voronoi cell, and the halo Voronoi cell volumes, and we show how halo abundances depend on these three quantities. We then study the position-dependent Voronoi density PDF, measured within finite subregions of the Universe, using separate universe simulations. We demonstrate that the spatial variation of the position-dependent PDF is due to large-scale density fluctuations, indicating that the position-dependent PDF is a biased tracer of large-scale structure. We measure this bias for the dark matter, and interpret it as the bias of regions of the Lagrangian density field that are selected based on density. For the halos, this bias can be interpreted as a form of assembly bias. We present the mapping from late-time to early-time Voronoi density for each simulation dark matter particle, which is highly stochastic. We compare the median of this stochastic map with spherical collapse calculations and discuss challenges involved in modeling the evolution of the density field on these scales.
