Cosmological Simulations of Formation of Galaxies and Clustersand Origin of biasing

(1)暗物质晕和高密度峰中的非线性随机偏置：我们使用宇宙学N体模拟来量化有偏物体集群的非线性和随机性程度。采用峰值和晕作为代表性的偏置模型，重点研究了有偏置的天体、暗物质的两点关联及其互相关。特别地，我们考虑了红移空间畸变的影响，并试图通过分析偏置因子和互相关因子来阐明尺度依赖性和时间依赖性。在小尺度上，随机性和非线性变得明显和强烈的对象相关，特别是在红移空间中，由于成对的速度色散的偏见对象。然而，确定性的线性偏置的近似工程相当不错，即使在准线性制度，线性红移空间的失真解释了集群振幅在红移空间在这个政权。 ...更多信息 (2)基于宇宙学流体动力学模拟的星系和星系团的偏置模型：我们利用宇宙学流体动力学模拟对空间平坦的低密度COM宇宙中星系和暗晕的非线性和随机偏置进行了广泛的分析。我们比较他们的偏置属性的分析晕偏置模型的预测。有趣的是，星系的偏置特性可以通过外推晕偏置模型的预测得到更好的描述。星系的成团振幅几乎与z=0和3之间的红移无关。我们还发现了星系偏置对它们的形成时代的明确依赖;星系的老种群的分布与底层的质量密度场密切相关，而年轻种群的分布相对于暗物质来说稍微更随机和反偏置。老年种群的两点相关函数的幅值比青年种群的幅值大3倍左右。此外，年老的星系群体居住在大质量的暗晕中，而年轻的星系则优先形成在较小的暗晕中。假设观测到的早型和晚型星系分别对应于模拟的老星系和年轻星系，所有这些星系的分离与观测的早型和晚型星系，如星系的形态-密度关系是一致的。少

(1) Nonlinear Stochastic Biasing in dark matter halos and high-density peaks : We quantifiesthe degree of nonlinearity and stochasticity of the clustering of biased objects, using cosmological N-body simulations. Adopting the peaks and the halos as representative biasing models, we focus on the two-point correlation of the biased objects, dark matter and their cross-correlation. Especially, we take account of the effect of redshift-space distortion and attempt to clarify the scale-dependence and the time-dependence by analyzing the biasing factor and the cross-correlation factor. On small scales, stochasticity and nonlinearity become appreciable and strongly object-dependent, especially in redshift space due to the pair-wise velocity dispersion of the biased objects. Nevertheless, an approximation of deterministic linear biasingworks reasonably well even in the quasi-linear regime, and linear redshift-space distortion explains the clustering amplitudes in redshift space in this regime. … More (2) Biasing model of galaxies and clusters on the basis of cosmological hydrodynamic simulations :We perform an extensive analysis of nonlinear and stochastic biasing of galaxies and dark halos in spatially flat low-density COM universe using cosmological hydrodynamic simulations. We compare their biasing properties with the predictions of an analytic halo biasing model. Interestingly the biasing properties of galaxies are better described by extrapolating the halo biasing model predictions. The clustering amplitudes of galaxies are almost independent of the redshift between z=0 and 3 as reported in previous simulations. We also find the clear dependence of galaxy biasing on their formation epoch ; the distribution of old populations of galaxies tightly correlates with the underlying mass density field, while that of young populations is slightly more stochastic and anti-biased relative to dark matter. The amplitude of two-point correlation function of old populations is about 3 times larger than that of the young populations. Furthermore, the old population of galaxies reside within massive dark halos while the young galaxies are preferentially formed in smaller dark halos. Assuming that the observed early and late-type galaxies correspond to the simulated old and young populations of galaxies, respectively, all of these segregations of galaxies are consistent with observational ones for the early and late-type of galaxies such as the morphology-density relation of galaxies. Less