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arXiv 0705.3643astro-ph
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低分辨率偏振3年WMAP天图的贝叶斯分析

Bayesian analysis of the low-resolution polarized 3-year WMAP sky maps

H. K. Eriksen, Greg Huey, A. J. Banday, K. M. Gorski, J. B. Jewell, I. J. O'Dwyer, B. D. Wandelt

摘要:

我们应用先前开发的吉布斯采样框架的前景校正3年WMAP偏振数据,并计算功率谱和剩余的前景模板幅度后验分布。我们首先分析了共同添加的Q-和V-波段数据,并将我们的结果与WMAP团队发布的可能性代码进行比较。我们发现很好的协议,从而验证了这两种方法的数值和数据处理步骤。然而,我们也分析了Q-和V-波段分别,允许非零EB互相关,并包括两个单独的前景模板振幅跟踪同步辐射和尘埃排放。在这些分析中,我们发现了系统学的初步证据:前景示踪物与Q和V波段的星图分别相关,但与共同叠加的QV星图不相关,在V波段星图中,在l <~ 16处有明显的负EB互相关;最后,当放宽EB和BB的限制时,Q频段和V频段的边缘频段功率之间存在明显差异。考虑到低电离能谱对再电离光学深度τ和标量扰动谱指数n_s的重要性,对这些特征的进一步研究是必要的。

英文摘要:

We apply a previously developed Gibbs sampling framework to the foreground corrected 3-yr WMAP polarization data and compute the power spectrum and residual foreground template amplitude posterior distributions. We first analyze the co-added Q- and V-band data, and compare our results to the likelihood code published by the WMAP team. We find good agreement, and thus verify the numerics and data processing steps of both approaches. However, we also analyze the Q- and V-bands separately, allowing for non-zero EB cross-correlations and including two individual foreground template amplitudes tracing synchrotron and dust emission. In these analyses, we find tentative evidence of systematics: The foreground tracers correlate with each of the Q- and V-band sky maps individually, although not with the co-added QV map; there is a noticeable negative EB cross-correlation at l <~ 16 in the V-band map; and finally, when relaxing the constraints on EB and BB, noticeable differences are observed between the marginalized band powers in the Q- and V-bands. Further studies of these features are imperative, given the importance of the low-l EE spectrum on the optical depth of reionization tau and the spectral index of scalar perturbations n_s.

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