Lack-of-correlation anomaly in CMB large scale polarisation maps
Lack-of-correlation anomaly in CMB large scale polarisation maps
复制标题
CMB大比例尺偏振图中的缺乏相关异常
DOI：
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发表时间：
2020
影响因子：
6.4
通讯作者：
L. Pagano
中科院分区：
文献类型：
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作者：
C. Chiocchetta;A. Gruppuso;M. Lattanzi;P. Natoli;L. Pagano
我们使用两点相关函数作为测试案例，对CMB的大尺度极化异常进行了评估。我们采用了最先进的大规模偏振数据集：第一个基于2018年HFI 100和143 GHz的跨谱分析，基于处理，第二个基于地图的方法，通过2018年LFI和-9年的联合处理而得出。我们考虑众所周知的S1/2估计器，该估计器在角度尺度大于60∘时测量两点相关函数从零到零的距离，并依赖于对两个数据集的真实模拟来评估可信区间。通过聚焦于由Q和U斯托克斯参数或由本地E模描述的纯极化场，我们表明，第一种描述受到四极矩(在两个数据集中约束很差)的严重影响，而第二种描述更适合于包含更高多极子的分析，直到ℓ∼10，超过该极限，两个数据集都变得明显的噪声主导。我们发现，这两个数据集在局域E模上都表现出与在温度上观测到的相似的缺乏相关性的异常，这种异常更好地受到噪声较小的数据的约束，其显著程度约为99.5%。我们使用受观测到的温度场约束或不受约束的实现来执行我们的分析，并且在两种情况下发现相似的结果。
We present an assessment of the large-scale CMB anomalies in polarisation using the two-point correlation function as a test case. We employ the state of the art of large scale polarisation datasets: the first based on a 2018 HFI 100 and 143 GHz cross-spectrum analysis, based on processing, and the second from a map-based approach derived through a joint treatment of 2018 LFI and -9yr. We consider the well-known S1/2 estimator, which measures the distance of the two-point correlation function from zero at angular scales larger than 60∘, and rely on realistic simulations for both datasets to assess confidence intervals. By focusing on the pure polarisation field described by either the Q and U Stokes parameters or by the local E-modes, we show that the first description is heavily influenced by the quadrupole (which is poorly constrained in both datasets) while the second one is more suited for an analysis containing higher multipoles up to ℓ∼ 10, limit above which both datasets become markedly noise dominated. We find that both datasets exhibit a lack-of-correlation anomaly in local E-modes, similar to the one observed in temperature, which is better constrained by the less noisy data, where its significance lies at about 99.5%. We perform our analysis using realizations that are either constrained or non-constrained by the observed temperature field, and find similar results in the two cases.
DOI：
10.17863/cam.43425
发表时间：
2016
期刊：
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影响因子：
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作者：
Aghanim N
通讯作者：
Aghanim N