普朗克中间结果。XIX。银河系尘埃的偏振热辐射综述
Planck intermediate results. XIX. An overview of the polarized thermal emission from Galactic dust
摘要：
本文介绍了大尺度偏振天空所看到的普朗克HFI在353 GHz，这是最敏感的普朗克通道尘埃偏振。我们构建和分析大规模的尘埃偏振分数和偏振方向的地图，同时考虑到噪声偏差和可能的系统性影响。我们发现观测到的最大尘埃极化率很高（pmax > 18%），特别是在一些中等尘埃柱密度（AV <1等）的区域。随着尘埃柱密度的增加，尘埃极化分数有一个系统的减少，我们解释了这种相关性的辐射晶粒排列预测和波动的磁场方向的特点。我们还使用角色散函数的偏振角的空间结构的特点，并发现，在附近的领域在中纬度地区，偏振角是有序的扩展区域，分离的非线性结构，出现的接口，磁场天空投影旋转突然没有明显的变化，尘埃柱密度。发现偏振分量与偏振角的色散是反相关的，这意味着这些变化可能是由于沿视线采样扩散星际介质的3D磁场方向的波动造成的。我们还将尘埃辐射与普朗克LFI测量的偏振同步辐射进行了比较，并与低频射电数据进行了比较，以及对河外源的法拉第旋转测量。这两个偏振分量在沿平面的结构上是全球相似的，特别是在扇形和北极支线区域。然而，对这三种示踪剂的详细比较表明，尘埃和宇宙射线通常会对视线的不同部分进行采样，并证实普朗克数据中观察到的大部分变化是由于磁场的三维结构。
英文摘要：
This paper presents the large-scale polarized sky as seen by Planck HFI at 353 GHz, which is the most sensitive Planck channel for dust polarization. We construct and analyse large-scale maps of dust polarization fraction and polarization direction, while taking account of noise bias and possible systematic effects. We find that the maximum observed dust polarization fraction is high (pmax > 18%), in particular in some of the intermediate dust column density (AV < 1mag) regions. There is a systematic decrease in the dust polarization fraction with increasing dust column density, and we interpret the features of this correlation in light of both radiative grain alignment predictions and fluctuations in the magnetic field orientation. We also characterize the spatial structure of the polarization angle using the angle dispersion function and find that, in nearby fields at intermediate latitudes, the polarization angle is ordered over extended areas that are separated by filamentary structures, which appear as interfaces where the magnetic field sky projection rotates abruptly without apparent variations in the dust column density. The polarization fraction is found to be anti-correlated with the dispersion of the polarization angle, implying that the variations are likely due to fluctuations in the 3D magnetic field orientation along the line of sight sampling the diffuse interstellar medium.We also compare the dust emission with the polarized synchrotron emission measured with the Planck LFI, with low-frequency radio data, and with Faraday rotation measurements of extragalactic sources. The two polarized components are globally similar in structure along the plane and notably in the Fan and North Polar Spur regions. A detailed comparison of these three tracers shows, however, that dust and cosmic rays generally sample different parts of the line of sight and confirms that much of the variation observed in the Planck data is due to the 3D structure of the magnetic field.
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