Analyzing the Intrinsic Magnetic Field in the Galactic Center Radio Arc
Analyzing the Intrinsic Magnetic Field in the Galactic Center Radio Arc
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DOI：
10.3847/1538-4357/ac2cc4
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发表时间：
2021-10
期刊：
影响因子：
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通讯作者：
Dylan M. Par'e;C. Purcell;C. Lang;M. Morris;J. Green
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作者：
Dylan M. Par'e;C. Purcell;C. Lang;M. Morris;J. Green
射电弧是位于银河系中心（GC）区域的一个有组织的非热灯丝（NTF）系统。最近对射电弧NTF的观察揭示了一个磁场，该磁场在平行和相对于灯丝方向旋转之间交替变化。这种模式与在其他GC NTF中观察到的主要平行磁场取向形成鲜明对比。为了帮助阐明这种模式的起源，我们分析光谱偏振数据的无线电弧NTFs使用澳大利亚望远镜紧凑阵列数据集覆盖的连续频率范围从2.4GHz到11 GHz的光谱分辨率为2 MHz。我们拟合去偏振模型的光谱偏振数据来表征沿着视线的法拉第效应。我们评估是否结构局部的无线电弧NTFs可能有助于不寻常的磁场方向。外部法拉第效应被确定为最有可能的起源的旋转观察到的无线电弧NTFs，然而，内部法拉第效应也被发现可能在平行磁场的区域。平行磁场区域中内部法拉第效应的可能性增加可能归因于GC局部结构的效应。一个这样的结构可以是Radio Arc NTF本地的Radio Shell。未来的研究需要确定这种交变磁场模式是否存在于其他多股NTFs中，或者是由射电弧NTFs局部复杂的星际区域产生的独特性质。
The Radio Arc is a system of organized nonthermal filaments (NTFs) located within the Galactic center (GC) region of the Milky Way. Recent observations of the Radio Arc NTFs revealed a magnetic field that alternates between being parallel and rotated with respect to the orientation of the filaments. This pattern is in stark contrast to the predominantly parallel magnetic field orientations observed in other GC NTFs. To help elucidate the origin of this pattern, we analyze spectro-polarimetric data of the Radio Arc NTFs using an Australian Telescope Compact Array data set covering the continuous frequency range from ∼4 to 11 GHz at a spectral resolution of 2 MHz. We fit depolarization models to the spectral polarization data to characterize Faraday effects along the line of sight. We assess whether structures local to the Radio Arc NTFs may contribute to the unusual magnetic field orientation. External Faraday effects are identified as the most likely origin of the rotation observed for the Radio Arc NTFs; however, internal Faraday effects are also found to be likely in regions of parallel magnetic field. The increased likelihood of internal Faraday effects in parallel magnetic field regions may be attributed to the effects of structures local to the GC. One such structure could be the Radio Shell local to the Radio Arc NTFs. Future studies are needed to determine whether this alternating magnetic field pattern is present in other multi-stranded NTFs, or is a unique property resulting from the complex interstellar region local to the Radio Arc NTFs.