Gradients of Synchrotron Polarization: Tracing 3D Distribution of Magnetic Fields
Gradients of Synchrotron Polarization: Tracing 3D Distribution of Magnetic Fields
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DOI：
10.3847/1538-4357/aad3ca
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发表时间：
2018-01
期刊：
影响因子：
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通讯作者：
A. Lazarian;K. Yuen
中科院分区：
文献类型：
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作者：
A. Lazarian;K. Yuen
我们描述了一种利用偏振同步辐射梯度探测星系和星系外二维和三维磁场分布的新技术。磁场的波动沿环境磁场被拉长。因此，场的变化在垂直于b场的方向上最大。这允许用同步加速器偏振梯度跟踪b场。我们证明了法拉第去极化允许我们绘制三维b场结构。去极化保证了极化梯度对靠近观测者的区域进行采样，采样深度由辐射频率控制。我们还利用梯度技术分析了同步加速器偏振波长导数沿视线方向的b场特性。这种同步加速器微分偏振梯度技术可以恢复底层b场的三维矢量。新技术不同于法拉第层析成像，因为它们提供了一种方法来绘制垂直于LOS的b场分量的3D分布。此外，我们发现偏振梯度与同步加速器偏振的对准可以用来分离前景的贡献与宇宙起源的偏振。我们注意到，同样的排列也存在于尘埃偏振。
We describe a new technique for probing galactic and extragalactic 2D and 3D magnetic field distribution using gradients of polarized synchrotron emission. The fluctuations of magnetic field are elongated along the ambient magnetic field. Therefore, the field variations are maximal perpendicular to the B-field. This allows tracing the B-field with synchrotron polarization gradients. We demonstrate that the Faraday depolarization allows us to map 3D B-field structure. The depolarization ensures that the polarization gradients sample the regions close to the observer with the sampling depth controlled by the frequency of radiation. We also analyze the B-field properties along the line of sight (LOS) by applying the gradient technique to the wavelength derivative of synchrotron polarization. This Synchrotron Derivative Polarization Gradients technique can recover the 3D vectors of the underlying B-fields. The new techniques are different from the Faraday tomography, as they provide a way to map the 3D distribution of B-field components perpendicular to the LOS. In addition, we find that the alignment of gradients of polarization with the synchrotron polarization can be used to separate the contribution of the foreground from the polarization of cosmological origin. We notice that the same alignment is also present for the dust polarization.