论文标题
一项研究星系形态与其大规模环境之间相互信息的统计意义的研究
A study on the statistical significance of mutual information between morphology of a galaxy and its large-scale environment
论文作者
论文摘要
已知在SDSS中存在于几十MPC的SDS中，已知存在星系形态与其大规模环境之间的非零互信息。如果有的话，重要的是要测试这些共同信息的统计意义。我们提出了三种不同的方法来测试这些非零相互信息的统计意义，并将其应用于SDSS和千年运行模拟。我们在不影响其空间分布的情况下随机将SDSS星系的形态信息随机，并比较原始数据和随机数据集中的相互信息。我们还将银河系分布分为较小的子立管，并随机将它们随机洗牌，以保持星系的形态信息完整。我们比较了原始SDSS数据中的相互信息及其用于不同洗牌长度的改组实现。使用t检验，我们发现形态和环境之间的较小但具有统计学意义的（置信水平为99.9％）的共同信息存在于整个长度尺度。我们还使用半分析星系目录中的模拟数据集进行了另一个实验，在该数据集中我们根据其位置的密度以受控方式将形态分配给星系。该实验清楚地表明，相互信息可以有效地捕获形态与环境之间的物理相关性。我们的分析表明，形态和环境之间的物理关联可能比目前所相信的更大的长度尺度以及此处介绍的信息理论框架可以充当组装偏置和星系特性大规模环境依赖性的敏感且有用的探针。
A non-zero mutual information between morphology of a galaxy and its large-scale environment is known to exist in SDSS upto a few tens of Mpc. It is important to test the statistical significance of these mutual information if any. We propose three different methods to test the statistical significance of these non-zero mutual information and apply them to SDSS and Millennium Run simulation. We randomize the morphological information of SDSS galaxies without affecting their spatial distribution and compare the mutual information in the original and randomized datasets. We also divide the galaxy distribution into smaller subcubes and randomly shuffle them many times keeping the morphological information of galaxies intact. We compare the mutual information in the original SDSS data and its shuffled realizations for different shuffling lengths. Using a t-test, we find that a small but statistically significant (at 99.9% confidence level) mutual information between morphology and environment exists upto the entire length scale probed. We also conduct another experiment using mock datasets from a semi-analytic galaxy catalogue where we assign morphology to galaxies in a controlled manner based on the density at their locations. The experiment clearly demonstrate that mutual information can effectively capture the physical correlations between morphology and environment. Our analysis suggests that physical association between morphology and environment may extend to much larger length scales than currently believed and the information theoretic framework presented here, can serve as a sensitive and useful probe of the assembly bias and large-scale environmental dependence of galaxy properties.
