Spectral Properties of Magnetohydrodynamic Turbulence Revealed by Polarization Synchrotron Emission with Faraday Rotation
Spectral Properties of Magnetohydrodynamic Turbulence Revealed by Polarization Synchrotron Emission with Faraday Rotation
复制标题
法拉第旋转偏振同步加速器发射揭示的磁流体动力湍流的光谱特性
DOI：
10.3847/1538-4357/aad182
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发表时间：
2018
影响因子：
4.9
通讯作者：
Xiang Fu Yuan
中科院分区：
文献类型：
--
作者：
Zhang Jian Fu;Lazarian Alex;Xiang Fu Yuan
在综合观测的基础上，研究了如何利用同步加速器极化辐射波动统计来恢复底层磁流体湍流的频谱特性。考虑空间重合、分离和复合同步辐射和法拉第旋转区域，提取同步辐射偏振强度沿视线积分的功率谱。我们的研究结果表明，在短波长范围内，功率谱反映了湍流磁场垂直分量的波动统计，而在长波长范围内，功率谱揭示了法拉第旋转密度的波动，法拉第旋转密度是磁场平行分量和热电子密度的乘积。我们发现我们的数值结果（在空间重合区域的情况下）与Lazarian & Pogosyan的分析预测是一致的，并且这种理论预测适用于更复杂的设置，即空间分离和复合区域。我们模拟了包含望远镜角度分辨率和噪声影响的望远镜观测，并发现可以成功地恢复潜在MHD湍流的统计数据。我们期望这项技术可以应用于各种天体物理环境，利用现有的同步加速器数据立方体和大量即将到来的数据集，如射电天文学低频阵列、平方公里阵列和500米口径球面射电望远镜。
We investigate how to recover the spectral properties of underlying magnetohydrodynamic (MHD) turbulence using fluctuation statistics of synchrotron polarization radiation, based on the synthetic observations. Taking spatially coincident, separated, and compounded synchrotron emission and Faraday rotation regions into account, we extract the power spectrum of synchrotron polarization intensities integrated along the line of sight. Our results demonstrate that in the short wavelength range, the power spectra reflect fluctuation statistics of the perpendicular component of turbulent magnetic fields, and the spectra at long wavelengths reveal the fluctuation of the Faraday rotation density, which is a product of the parallel component of magnetic field and thermal electron density. We find that our numerical results (in the case of spatially coincident regions) are in agreement with the analytical prediction in Lazarian & Pogosyan, and this theoretical prediction is applicable to more complicated settings, i.e., the spatially separated and compounded regions. We simulate telescopic observations that incorporate the effects of telescope angular resolution and noise, and find that statistics of underlying MHD turbulence can be recovered successfully. We expect that the technique can be applied to a variety of astrophysical environments, with existing synchrotron data cubes and a large number of forthcoming data sets from such as the LOw Frequency Array for Radio astronomy, the Square Kilometer Array, and the Five-hundred-meter Aperture Spherical radio Telescope.