arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2008.08164astro-ph.CO
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从图熵的角度看宇宙网

The cosmic web through the lens of graph entropy

María Valentina García-Alvarado, Jaime E. Forero-Romero, Xiao-Dong Li

摘要:

我们探索的信息论熵的图作为一个标量来量化宇宙网络。我们发现熵值在1.5和3.2位之间的范围内。我们认为,这种熵可以被用来作为一个离散的模拟标量用于量化连续密度场的连接。在表明熵清楚地区分了聚集点和随机点之后,我们使用模拟来衡量测量几何形状,宇宙方差,红移空间扭曲,红移演化,宇宙学参数和空间数密度的影响。宇宙方差的影响最小,而从调查的几何形状,红移空间扭曲,宇宙学参数和红移演化的变化产生较大的变化的顺序上的$10^{-2}$位。对图熵的最大影响来自于聚类点的数量密度的变化。随着数量密度的降低,宇宙网变得不那么明显,熵可以减少到0.2比特。图熵计算简单,可以应用于模拟和大星系红移巡天的观测数据;它是一种新的统计量,可以与其他类型的拓扑或聚类测量互补。

英文摘要:

We explore the information theory entropy of a graph as a scalar to quantify the cosmic web. We find entropy values in the range between 1.5 and 3.2 bits. We argue that this entropy can be used as a discrete analogue of scalars used to quantify the connectivity in continuous density fields. After showing that the entropy clearly distinguishes between clustered and random points, we use simulations to gauge the influence of survey geometry, cosmic variance, redshift space distortions, redshift evolution, cosmological parameters and spatial number density. Cosmic variance shows the least important influence while changes from the survey geometry, redshift space distortions, cosmological parameters and redshift evolution produce larger changes on the order of $10^{-2}$ bits. The largest influence on the graph entropy comes from changes in the number density of clustered points. As the number density decreases, and the cosmic web is less pronounced, the entropy can diminish up to 0.2 bits. The graph entropy is simple to compute and can be applied both to simulations and observational data from large galaxy redshift surveys; it is a new statistic that can be used in a complementary way to other kinds of topological or clustering measurements.

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