arXiv 1305.74412013-05-31astro-ph.CO

伪谱方法估计宇宙微波背景B模功率谱的有效性

Efficiency of pseudo-spectrum methods for estimation of Cosmic Microwave Background B-mode power spectrum

A. Ferte, J. Grain, M. Tristram, R. Stompor

备注：: 23 pages, 10 figures
发表信息：: Phys. Rev. D 88, 023524 (2013)
DOI：: 10.1103/PhysRevD.88.023524

摘要：

估算宇宙微波背景（CMB）极化各向异性的B模式角功率谱是充分利用该探测器科学潜力的关键一步。在伪谱方法的上下文中，主要挑战与B模式谱估计与大得多的E模式的剩余功率的污染有关。这种所谓的E-to-B泄漏是必然存在的，只要一个不完整的天空地图是唯一可用的，因为是任何现实的观察。然后必须最小化或去除泄漏，并且理想地以既不引入偏差也不引入额外方差的方式。在本文中，我们从这两个角度比较最近在这方面提出的三种不同的方法。Smith 2006，Zhao & Baskaran 2010，Kim & Naselsky 2010，我们首先在所谓的chi场的公共代数框架内引入，然后研究它们在两种不同实验配置上的性能-一种对应于覆盖当前地基或气球实验的1%天空的小规模实验，另一种对应于几乎全天空的实验，例如，在一个实施例中，可能的CMB B模式卫星任务。我们发现，虽然所有这些方法允许显着降低的水平的E-to-B泄漏，这是史密斯2006年的方法，它在同一时间确保最小的误差条在所有实验配置研究在这里，由于事实上，它允许直接优化的天空切趾的偏振图用于估计。对于类似卫星的实验，该方法使得能够在大角度尺度下检测B模式功率谱，但仅在适当的合并之后。Zhao & Baskaran 2010的方法在几乎全天空覆盖的情况下是一个接近亚军。

英文摘要：

Estimation of the B-mode angular power spectrum of polarized anisotropies of the cosmic microwave background (CMB) is a key step towards a full exploitation of the scientific potential of this probe. In the context of pseudo-spectrum methods the major challenge is related to a contamination of the B-mode spectrum estimate with residual power of much larger E-mode. This so-called E-to-B leakage is unavoidably present whenever an incomplete sky map is only available, as is the case for any realistic observation. The leakage has to be then minimized or removed and ideally in such a way that neither a bias nor extra variance is introduced. In this paper, we compare from these two perspectives three different methods proposed recently in this context Refs. Smith 2006, Zhao & Baskaran 2010, Kim & Naselsky 2010, which we first introduce within a common algebraic framework of the so-called chi-fields and then study their performance on two different experimental configurations - one corresponding to a small-scale experiment covering 1% of the sky motivated by current ground-based or balloon-borne experiments and another - to a nearly full-sky experiment, e.g., a possible CMB B-mode satellite mission. We find that though all these methods allow to reduce significantly the level of the E-to-B leakage, it is the method of Smith 2006, which at the same time ensures the smallest error bars in all experimental configurations studied here, owing to the fact that it permits straightforwardly for an optimization of the sky apodization of the polarization maps used for the estimation. For a satellite-like experiment, this method enables a detection of B-mode power spectrum at large angular scales but only after appropriate binning. The method of Zhao & Baskaran 2010 is a close runner-up in the case of a nearly full sky coverage.

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