用线性回归法估计多频天图的单极子和偶极子
Monopole and dipole estimation for multi-frequency sky maps by linear regression
摘要：
我们描述了一种简单而有效的方法，用于推导出一组一致的多频天空图数据集的偶极子和偶极子校正，允许使用相同的数据集进行鲁棒的参数分量分离。该方法的计算核心是频率图对之间的线性回归，通常称为“T-T图”。个别的贡献，从偶极子和偶极子项是通过执行本地在天空上的补丁回归，而不同的频率之间的简并被解除时，占主导地位的前景成分表现出显着的空间光谱指数变化。基于这种方法，我们提出了两个不同的，但每个内部一致的，9年WMAP，普朗克2013年，SFD 100 um，Haslam 408 MHz和Reich & Reich 1420 MHz地图的偶极子和偶极子系数集。这两组数据是在不同的分析假设和数据选择下得出的，并提供了对剩余系统不确定性的估计。在一般情况下，我们的价值观是在良好的协议与以前公布的结果。其中最值得注意的结果是WMAP和普朗克实验之间的相对偶极子为10-15 uK（取决于频率），408 MHz地图的估计值为8.9 +-1.3 K，1420 MHz地图中的非零偶极子为0.15 +-0.03 K，指向银河系坐标（l，b）=（308，-36）± 14度。这些值代表了所有仪器和数据处理偏移量的总和，以及在整个天空中光谱均匀的任何银河或银河外分量。
英文摘要：
We describe a simple but efficient method for deriving a consistent set of monopole and dipole corrections for multi-frequency sky map data sets, allowing robust parametric component separation with the same data set. The computational core of this method is linear regression between pairs of frequency maps, often called "T-T plots". Individual contributions from monopole and dipole terms are determined by performing the regression locally in patches on the sky, while the degeneracy between different frequencies is lifted when ever the dominant foreground component exhibits a significant spatial spectral index variation. Based on this method, we present two different, but each internally consistent, sets of monopole and dipole coefficients for the 9-year WMAP, Planck 2013, SFD 100 um, Haslam 408 MHz and Reich & Reich 1420 MHz maps. The two sets have been derived with different analysis assumptions and data selection, and provides an estimate of residual systematic uncertainties. In general, our values are in good agreement with previously published results. Among the most notable results are a relative dipole between the WMAP and Planck experiments of 10-15 uK (depending on frequency), an estimate of the 408 MHz map monopole of 8.9 +- 1.3 K, and a non-zero dipole in the 1420 MHz map of $0.15 +- 0.03 K pointing towards Galactic coordinates (l,b) = (308,-36) +- 14 degrees. These values represent the sum of any instrumental and data processing offsets, as well as any Galactic or extra-Galactic component that is spectrally uniform over the full sky.
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