缪海兴, 张杨*, 侯永辉
( 中国科技大学; )
职称论文发表摘要: 渝渗是一种应用广泛的统计模型,用其临界状态来描述宇 宙大尺度结构,能自然给出近似幂律形式的星系关联函数,定性地 分析能演化到与观测相近的结果。但是处于临界状态就要 求描述系统的传播几率$P=P_c$,这与星系形成的实际过程并不符合。 更合理的情况应该用允许几率随星系形成过程而改 变的自组织的渝渗模型。我们在三维空间的简单立方格点上模拟了这 种过程,得到星系空间分布的模拟样本, 并进而计算了相应的星系关联函数$\xi(r)$,发现这个自组织渝渗模型 的结果与临界状态的渝渗模型的结果相近。另外,我们还计算 了对应的功率谱$P(k)$,在大尺度上$P(k) \propto k^{-2.1}$, 在小尺度上$P(k)\propto k^{-2.6}$,这与观测结果接近。 从几何上看,空间的非格点模型要比格点模型更接近于 实际的星系的空间分布。 我们在这种非格点模型中进行了模拟计算,具体步骤和公式类似于 格点模型的情况,所得到的$\xi(r)$和相应的功率谱$P(k)$的 形状与格点模型的相似。 由于渝渗模型作为一个统计模型,未能够反映小尺度上星系间的引力相互作用, 导致模型预言的小尺度上的关联不足。
职称论文发表 关键词: 大尺度结构,关联函数,
Miao Haixing, Zhang Yang *, Hou Yonghui
( University of Science and Technology of China; )
Abstract: A study on the large scale structure of the Universe is carried out in the percolation model commonly used to explain continuous phase transition. Although the critical-state percolation model previously studied accords qualitatively with the observational result, a fine-tuning parameter, the propagation probability $P=P_c$, is required in order to keep the system in the critical state. By analysising the formation process of galaxies, it is noted that the self-organized percolation model without the fine-tuning takes into account of the back-reaction from the enveroment of the actual structure formation. Based on this self-organized percolation model, we have performed numerical simulations on the simple cubic lattice in 3-dim space, obtained the numerical samples for the spatial galaxy distribution, and calculated the two-point correlation function $\xi(r)$, which is quite similar to that from the percolation model in critical state. We have also given the corresponding power spectrum $P(k)$, which behaves $\sim k^{-2.1}$ on large scale, and $\sim k^{-2.6}$ on small scale, also agreeing qualitatively with the observations. Goemetrically the spatial distribution of galaxies is more adequately described by the off-lattice model instead of the simple cubic lattice model. We have also performed simulations on the off-lattice, and the resulting $\xi(r)$ and $P(k)$ are similar to the lattice case. The major difficulty with the percolation models of the structure formation is insufficient correlation on small scales since it does not take into account of the inter-galaxy gravity.
Keywords: Large scale structure, Correlation Function,
中国科技论文在线:缪海兴,张杨,侯永辉. 组织渝渗模型中的宇宙大尺度结构[EB/OL].北京:中国科技论文在线
发表期刊: 暂无