arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 2104.00418astro-ph.CO
收藏

检验普朗克收敛图统计各向同性的局部块分析

Local patch analysis for testing statistical isotropy of the Planck convergence map

Priya Goyal, Pravabati Chingangbam

摘要:

微弱的引力透镜效应对宇宙微波背景辐射的影响虽小但可测量,它提供了宇宙中物质大尺度分布的信息。我们利用普朗克巡天CMB透镜测量得到的{ \em收敛图}所表示的全天物质分布来检验宇宙统计各向同性(SI)的基本假设。对于分析,我们使用的$α$统计,设计从轮廓Minkowski张量,张量推广的标量Minkowski功能,轮廓长度。本质上,$α$统计量捕获在平滑随机场的任何所选阈值处的等场轮廓的椭圆率,并提供各向异性的度量。所观察到的收敛图的SI测试对现实模拟的收敛图提供的普朗克合作套件。我们首先进行了全球性的分析,使用全天空数据后,应用银河和点源掩模。我们发现,观测数据是一致的SI。此外,我们进行了本地搜索偏离SI在小补丁的天空使用$α$。该分析揭示了几个天空斑块,其显示出与模拟的偏差,具有高于95%置信水平(CL)的统计显著性。我们的分析表明,大多数离群补丁的异常行为的来源是不准确的估计噪声。我们确定了两个离群补丁表现出异常行为起源于偏离SI高于95\% CL。大多数的异常斑块被发现大致位于沿黄道面或接近黄道两极。

英文摘要:

The small but measurable effect of weak gravitational lensing on the cosmic microwave background radiation provide information about the large-scale distribution of matter in the universe. We use the all sky distribution of matter, as represented by the {\em convergence map} that is inferred from CMB lensing measurement by Planck survey, to test the fundamental assumption of Statistical Isotropy (SI) of the universe. For the analysis we use the $α$ statistic that is devised from the contour Minkowski tensor, a tensorial generalization of the scalar Minkowski functional, the contour length. In essence, the $α$ statistic captures the ellipticity of isofield contours at any chosen threshold value of a smooth random field and provides a measure of anisotropy. The SI of the observed convergence map is tested against the suite of realistic simulations of the convergence map provided by the Planck collaboration. We first carry out a global analysis using the full sky data after applying the galactic and point sources mask. We find that the observed data is consistent with SI. Further we carry out a local search for departure from SI in small patches of the sky using $α$. This analysis reveals several sky patches which exhibit deviations from simulations with statistical significance higher than 95\% confidence level (CL). Our analysis indicates that the source of the anomalous behaviour of most of the outlier patches is inaccurate estimation of noise. We identify two outlier patches which exhibit anomalous behaviour originating from departure from SI at higher than 95\% CL. Most of the anomalous patches are found to be located roughly along the ecliptic plane or in proximity to the ecliptic poles.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑