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arXiv 1710.00580astro-ph.CO
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从PLANCK得到的CMB极化图中的功率不对称性:局部方差分析

Power asymmetry in CMB polarization maps from PLANCK : a local variance analysis

Pavan K. Aluri, Arman Shafieloo

摘要:

在迄今为止的全天空温度测量中,发现了CMB天空相对半球上功率不对称的持续信号。这种不对称性在WMAP和普朗克卫星的微波天空中就被发现了,这引起了人们对\emph{statistical isotropy}这个更大问题的关注,它是现代宇宙学的基本原理之一。在这项工作中,我们提出了从普朗克2015年完整的任务数据极化CMB地图的分析。我们将局部方差估计器应用于来自普朗克2015偏振\texttt{Commander}解决方案的低分辨率$E-$模式图。我们发现一个显着的半球形功率不对称的偏振数据在大的角度尺度上,在$\sim 2.6-3.9\%$的水平取决于银河掩模,和用于计算本地方差图的圆盘半径。然而,方向被发现是指向广泛的CMB动力学偶极子方向。未来对CMB偏振的精确测量将揭示温度和偏振CMB天空中各向异性轴的明显差异,以及系统学对我们研究结果的可能影响。

英文摘要:

A persistent signal of power asymmetry on opposite hemispheres of CMB sky was seen in full-sky temperature measurements made so far. This asymmetry was seen in microwave sky from WMAP as well as PLANCK satellites, and calls for attention the larger question of \emph{statistical isotropy}, one of the foundational principles of modern cosmology. In this work we present an analysis of polarized CMB maps from PLANCK 2015 full mission data. We apply the local variance estimator on low resolution $E-$mode maps from PLANCK 2015 polarization \texttt{Commander} solution. We find a significant hemispherical power asymmetry in polarization data on large angular scales, at the level of $\sim 2.6-3.9\%$ depending on the galactic mask, and the circular disc radius used for computing local variance maps. However the direction is found to be pointing broadly towards CMB kinetic dipole direction. Precise measurements of CMB polarization in future will shed light on this apparent discrepancy in the anisotropy axis seen in temperature and polarized CMB sky, and likely influence of systematics on our findings.

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