爬行宇宙网络：探索星系分布中的结构形态
Crawling the Cosmic Network: Exploring the Morphology of Structure in the Galaxy Distribution
摘要：
虽然相干的大尺度结构，如细丝和墙壁是显而易见的星系红移调查，他们迄今为止被证明难以用计算机算法来表征。本文提出了一种利用星系密度场Hessian矩阵的特征值和特征向量来表征大尺度结构形态的方法。通过分析平滑的密度场及其海森矩阵，我们可以确定结构的类型-壁，细丝或团块-作为尺度的函数主导星系的大尺度分布。我们已经运行的模拟星系分布的LCDM宇宙学N体模拟和斯隆数字巡天观测到的星系分布的算法。两个星表的结构形态相似，在10 - 20 h ^{-1} Mpc平滑尺度上均以顺磁为主，在5 h ^{-1} Mpc尺度上均以团块为主。在这两种分布中都有壁存在的证据，但在小于~25 h ^{-1} Mpc的尺度上，壁并不是主要的结构。模拟的分析表明，在一个给定的共动平滑尺度，结构随着时间的推移，从墙壁到细丝到团块，在较小的平滑尺度上发现的那些在给定的时间进一步在这个过程中。
英文摘要：
Although coherent large-scale structures such as filaments and walls are apparent to the eye in galaxy redshift surveys, they have so far proven difficult to characterize with computer algorithms. This paper presents a procedure that uses the eigenvalues and eigenvectors of the Hessian matrix of the galaxy density field to characterize the morphology of large-scale structure. By analysing the smoothed density field and its Hessian matrix, we can determine the types of structure - walls, filaments, or clumps - that dominate the large-scale distribution of galaxies as a function of scale. We have run the algorithm on mock galaxy distributions in a LCDM cosmological N-body simulation and the observed galaxy distributions in the Sloan Digital Sky Survey. The morphology of structure is similar between the two catalogues, both being filament-dominated on 10-20 h^{-1} Mpc smoothing scales and clump-dominated on 5 h^{-1} Mpc scales. There is evidence for walls in both distributions, but walls are not the dominant structures on scales smaller than ~25 h^{-1} Mpc. Analysis of the simulation suggests that, on a given comoving smoothing scale, structures evolve with time from walls to filaments to clumps, where those found on smaller smoothing scales are further in this progression at a given time.
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