标题： 广义泊松分布和从泊松初始条件的聚类模型 显示英文标题

标题： The Generalized Poisson distribution and a model of clustering from Poisson initial conditions

摘要： 本文提出广义泊松分布的一种新推导方法。 此分布很好地拟合了基于泊松初始条件的分层聚类数值模拟中测得的演化计数分布。 这种新的推导方法可用于构建这些模拟中测量到的聚类演化的有用解析模型。 该模型与以下假设一致：随着宇宙膨胀和引力不稳定性导致的区域共动尺度变化，这些膨胀和收缩区域的数量是守恒的。 该模型忽略了外部潮汐效应对这些区域演化的影响。 事实上，在该模型的框架下，广义泊松分布可以被视为球状坍缩模型的一个简单变体，其中也忽略了潮汐效应。 该模型可以理解为穿越集模型的一个简单推广，用于估计坍缩、星系团化晕的数密度。 这种推广允许同时描述晕的空间分布和质量，因此很容易估算这些晕对底层物质分布的偏倚程度。 显示英文摘要

摘要： This paper presents a new derivation of the Generalized Poisson distribution. This distribution provides a good fit to the evolved, counts-in-cells distribution measured in numerical simulations of hierarchical clustering from Poisson initial conditions. This new derivation can be used to construct a useful analytic model of the evolution of clustering measured in these simulations. The model is consistent with the assumption that, as the universe expands and the comoving sizes of regions change as a result of gravitational instability, the number of such expanding and contracting regions is conserved. The model neglects the influence of external tides on the evolution of such regions. Indeed, in the context of this model, the GPD can be thought of as arising from a simple variant of the well-studied spherical collapse model, in which tidal effects are also neglected. The model can be understood as a simple generalization of the excursion set model which is used to estimate the number density of collapsed, virialized halos. The generalization allows one to describe the spatial distribution of the halos and the mass simultaneously, so the extent to which these halos are biased tracers of the underlying matter distribution is easy to estimate.