论文标题
前景模型在大角度尺度上的CMB E模式极化的关节后部独立估计
A Foreground Model Independent Estimation of Joint Posterior of CMB E mode Polarization over Large Angular Scales
论文作者
论文摘要
由于宇宙微波背景（CMB）信号通过基于各种卫星的观测值来衡量，实验精确量的提高，对CMB重建技术的需求却相似地增加了CMB信号的准确估计，该技术可以提供对理论角度功能谱的准确估计以及与他们相关的可靠统计误差估计。在这项工作中，我们估计了CMB E模式信号的关节后验和相应的理论角功率谱（C^E_L），鉴于未来一代核心卫星任务的模拟极化观察结果，在大角度尺度上。为了从联合分布中生成样品，我们采用了ILC技术，并使用GIBBS采样技术增强了CMB E模式协方差矩阵的先前信息。我们使用全科体样品估算了S和C^e_l的边缘密度。最合适的清洁模式图和相应的角功率谱与输入E模式图和天空功率谱非常吻合，这意味着使用核心等观测值精确地重建。使用所有Gibbs链的样品C^e_l，我们估计了在Blackwell-Rao估计器之后的模拟观察到的核心任务的任何任意C^e_l的可能性函数P（C^E_L | D）。可能性函数可以无缝地集成到宇宙参数估计方法中。除了在大角度尺度上产生E模式信号的准确估计，我们的方法还使用CMB E模式观测值在大型角度尺度上建立了组件重建和可靠的宇宙学参数估计。整个方法不假定E模式前景组件的任何明确模型以删除它们，这是一个有吸引力的属性，因为在这种情况下，前景建模不确定性并不是挑战。
Ever since Cosmic Microwave Background (CMB) signal is being measured by various satellites based observations with increasing experimental accuracies there has been a parallel increase in the demand for a CMB reconstruction technique which can provide accurate estimates of CMB signal and the theoretical angular power spectrum along with reliable statistical error estimates associated with them. In this work, we estimate the joint posterior of CMB E mode signal (S) and corresponding theoretical angular power spectrum (C^E_l) over large angular scales given the simulated polarization observations of future generation COrE satellite mission. To generate samples from the joint distribution we employ the ILC technique with prior information of CMB E mode covariance matrix augmented by a Gibbs sampling technique. We estimate the marginalized densities of S and C^E_l using the samples from full-posterior. The best fit cleaned E mode map and the corresponding angular power spectrum agree well with the input E mode map and the sky power spectrum implying accurate reconstruction using COrE like observations. Using the samples C^E_l of all Gibbs chains we estimate the likelihood function P(C^E_l|D) of any arbitrary C^E_l given simulated observed maps (D) of COrE mission following Blackwell-Rao estimator. The likelihood function can be seamlessly integrated to the cosmological parameter estimation method. Apart from producing an accurate estimate of E mode signal over large angular scales our method also builds a connection between the component reconstruction and reliable cosmological parameter estimation using CMB E mode observations over large angular scales. The entire method does not assume any explicit models for E mode foreground components in order to remove them, which is an attractive property since foreground modelling uncertainty does not pose as a challenge in this case.
