WMAP 3-yr data with Correlated Component Analysis: anomalous emission and impact of component separation on the CMB power spectrum
WMAP 3-yr data with Correlated Component Analysis: anomalous emission and impact of component separation on the CMB power spectrum
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WMAP 3 年数据及相关成分分析：异常发射和成分分离对 CMB 功率谱的影响
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
G. Zotti
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文献类型：
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作者：
A. Bonaldi;S. Ricciardi;S. Leach;F. Stivoli;C. Baccigalupi;G. Zotti
相关成分分析（CCA）使我们能够通过宇宙微波背景（CMB）实验来估计不同的漫射发射如何在观测中混合，同时考虑到其他调查的补充信息。它特别适用于处理可能的附加组件，这些组件的先验信息很少或根本没有。CCA的应用程序的威尔金森微波各向异性探测器（WMAP）的地图，假设只有典型的银河系的排放（同步辐射，自由和热尘埃）的存在突出了广泛存在的光谱辐射“同步辐射”的组成部分，基本上不相关的同步辐射模板，这表明一个额外的前景确实需要。我们已经测试了这种成分的各种光谱形状，即如果它在同步加速器上被激发，则预期的幂律，以及两种可能适合旋转尘埃发射的光谱形状：log S − log ν平面上的抛物线和灰体。如果额外的（“异常”）组件的空间分布是不受约束的先验，它总是紧密相关的热尘，但相关性是不完美的。对重建的CMB图进行的质量测试明显不利于两种模型。利用三个幸存的前景模型重建的CMB图估计的CMB功率谱通常与WMAP团队获得的功率谱一致，尽管至少有一个模型给出的四极矩比WMAP发现的要高得多。考虑到前景模型的不确定性，我们发现三个“好”模型的平均四极振幅比标准冷暗物质（CDM）模型的预期值低1 σ。此外，除l（cid：2）40处的过剩屈光度外，其他报告的模型预测偏差在统计学上不显著。我们确认了大尺度（l < 20）CMB各向异性中明显的南北不对称性的证据，这对于我们采用的前景参数化是稳定的。我们还提出了第一个，尽管是初步的，全天空的“异常发射”模板。
Correlated Component Analysis (CCA) allows us to estimate how the different diffuse emissions mix in observations by cosmic microwave background (CMB) experiments, also taking into account complementary information from other surveys. It is especially useful for dealing with possible additional components for which little or no prior information exists. An application of CCA to the Wilkinson Microwave Anisotropy Probe ( WMAP ) maps assuming that only the canonical Galactic emissions (synchrotron, free–free and thermal dust) are present highlights the widespread presence of a spectrally flat ‘synchrotron’ component, largely uncorrelated with the synchrotron template, suggesting that an additional foreground is indeed required. We have tested various spectral shapes for such a component, namely a power law as is expected if it is flat synchrotron, and two spectral shapes that may fit the spinning dust emission: a parabola in the log S − log ν plane and a grey body. If the spatial distribution of the additional (‘anomalous’) component is not constrained a priori, it is found to be always tightly correlated with thermal dust, but the correlation is not perfect. Quality tests applied to the reconstructed CMB maps clearly disfavour two of the models. The CMB power spectra, estimated from CMB maps reconstructed exploiting the three surviving foreground models, are generally consistent with those obtained by the WMAP team, although at least one of the models gives a significantly higher quadrupole moment than found by WMAP . Taking foreground modelling uncertainties into account, we find that the mean quadrupole amplitude for the three ‘good’ models is less than 1 σ below the expectation from the standard (cid:5) cold dark matter ( (cid:5) CDM) model. Also, the other reported deviations from model predictions are found not to be statistically significant, except for the excess power at l (cid:2) 40. We confirm the evidence for a marked north–south asymmetry in the large-scale ( l < 20) CMB anisotropies, which is stable with respect to the foreground parametrization we adopted. We also present a first, albeit preliminary, all-sky template of the ‘anomalous emission’.