Constraining the Magnetic Field of the Smith High-velocity Cloud Using Faraday Rotation
Constraining the Magnetic Field of the Smith High-velocity Cloud Using Faraday Rotation
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DOI：
10.3847/1538-4357/aaf886
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发表时间：
2018-12
期刊：
影响因子：
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通讯作者：
S. Betti;A. Hill;S. A. Mao;B. Gaensler;F. J. Lockman;N. McClure-Griffiths;R. Benjamin
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文献类型：
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作者：
S. Betti;A. Hill;S. A. Mao;B. Gaensler;F. J. Lockman;N. McClure-Griffiths;R. Benjamin
史密斯云是一种高速云，其轨道表明它至少通过过一次银河系。在这团云周围发现的磁场被认为在它穿过银晕时提供了额外的稳定性。我们使用Karl G. Jansky甚大阵列测量了Smith云背后和旁边的1105个河外背景点源的法拉第旋转测量值（RMs），以约束其磁场的详细几何形状和强度。穿过云的RM模式给出了磁场结构的详细形态，这表明一个覆盖在电离气体上并在云的头部被压缩的场。我们将峰值视距磁场强度限制在±5 μG，并创建了一个磁场模型，以证明覆盖结构可以定性地解释观测到的均方根的形态。
The Smith Cloud is a high-velocity cloud with an orbit suggesting it has made at least one passage through the Milky Way disk. A magnetic field found around this cloud has been thought to provide extra stability as it passes through the Galactic halo. We use the Karl G. Jansky Very Large Array to measure Faraday rotation measures (RMs) toward 1105 extragalactic background point sources behind and next to the Smith Cloud to constrain the detailed geometry and strength of its magnetic field. The RM pattern across the cloud gives the detailed morphology of the magnetic field structure, which indicates a field draped over the ionized gas and compressed at the head of the cloud. We constrain the peak line-of-sight magnetic field strength to ≳+5 μG and create a model of the magnetic field to demonstrate that a draped configuration can qualitatively explain the morphology of the observed RMs.