The Mean Pairwise Peculiar Velocity in Cosmological N-Body Simulations: Time Variation, Scale Dependence, and the Stable Condition
The Mean Pairwise Peculiar Velocity in Cosmological N-Body Simulations: Time Variation, Scale Dependence, and the Stable Condition
复制标题
宇宙学 N 体模拟中的平均成对奇异速度：时间变化、尺度依赖性和稳定条件
DOI：
10.1086/323042
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Y. Suto
中科院分区：
文献类型：
--
作者：
T. Fukushige;Y. Suto
本文详细分析了高分辨率宇宙学N体模拟（N = 8.8 × 106粒子，球半径为50-200 Mpc）中平均成对奇特速度剖面。特别是，我们研究的有效性和局限性的稳定条件，这表明粒子对的平均物理分离是恒定的小尺度。我们发现一个显着的时间变化（一个不规则的振荡行为）的平均成对特有的速度在非线性制度。我们认为，这种行为是不是由于任何数值工件，但在层次聚类宇宙中的连续合并过程是一个自然的后果。虽然这样的时间变化在相对局部的宇宙中是显着的，但在200 Mpc 3的巨大空间体积上的全球平均值并没有显示出任何系统性的偏离稳定条件。因此，我们的结论是，平均成对特有速度是相当不稳定的统计，但它仍然满足稳定的条件时，平均宇宙体积。
We report on the detailed analysis of the mean pairwise peculiar velocity profile in high-resolution cosmological N-body simulations (N = 8.8 × 106 particles in a sphere of 50-200 Mpc radius). In particular, we examine the validity and limitations of the stable condition, which states that the mean physical separation of particle pairs is constant on small scales. We find a significant time variation (an irregular oscillatory behavior) in the mean pairwise peculiar velocity in nonlinear regimes. We argue that this behavior is not due to any numerical artifact but is a natural consequence of the continuous merging processes in the hierarchical clustering universe. While such a time variation is significant in a relatively local patch of the universe, the global average over a huge spatial volume of ≳200 Mpc3 does not reveal any systematic departure from the stable condition. Thus, we conclude that the mean pairwise peculiar velocity is rather unstable statistically but that it still satisfies the stable condition when averaged over the cosmological volume.