标题： 单点分布从高斯初始波动的演化 显示英文标题

标题： Evolution of One-Point Distributions from Gaussian Initial Fluctuations

摘要： 我们研究了宇宙引力系统中平滑密度和速度场的一点概率密度函数（PDF）的准线性演化，这些系统起始于高斯初始涨落。 我们的解析结果基于泽尔多维奇近似和层流流动。 数值分析通过CDM N体模拟的平滑场将结果扩展到多流区。 我们发现，在层流泽尔多维奇近似下，无论是拉格朗日还是欧拉的流速PDF保持为高斯分布，并且在模拟中几乎与高斯分布无法区分。 质量密度的PDF在准线性阶段早期偏离正态分布，并发展出一种形状，与具有一个参数（密度涨落\rms 的$\sigma$）的对数正态分布非常相似。 将这些结果应用于目前可用的数据，我们发现流速和密度场的PDF，如通过假设$\Omega=1$的观测流速恢复的\pot 程序所得到的，或者假设星系追踪质量的\iras 星系红移调查所推断的，都与高斯初始涨落一致。 显示英文摘要

摘要： We study the quasilinear evolution of the one-point probability density functions (PDFs) of the smoothed density and velocity fields in a cosmological gravitating system beginning with Gaussian initial fluctuations. Our analytic results are based on the Zel'dovich approximation and laminar flow. A numerical analysis extends the results into the multistreaming regime using the smoothed fields of a CDM N-body simulation. We find that the PDF of velocity, both Lagrangian and Eulerian, remains Gaussian under the laminar Zel'dovich approximation, and it is almost indistinguishable from Gaussian in the simulations. The PDF of mass density deviates from a normal distribution early in the quasilinear regime and it develops a shape remarkably similar to a lognormal distribution with one parameter, the \rms density fluctuation $\sigma$. Applying these results to currently available data we find that the PDFs of the velocity and density fields, as recovered by the \pot\ procedure from observed velocities assuming $\Omega=1$, or as deduced from a redshift survey of \iras\ galaxies assuming that galaxies trace mass, are consistent with Gaussian initial fluctuations.