Magnetic field structure and halo in NGC 4631
Magnetic field structure and halo in NGC 4631
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NGC 4631 中的磁场结构和光晕
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
M. Krause
中科院分区：
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作者：
Silvia Carolina Mora;M. Krause
为了弄清NGC 4631是否有一个独特的磁场配置在中心区域沿着其磁盘，我们提出了高分辨率的法拉第校正的偏振数据。使用VLA对NGC 4631进行了4.85 GHz的射电连续谱观测。此外，还用Effelsberg望远镜在4.85 GHz和8.35 GHz进行了观测。这些与8.35 GHz的VLA存档数据一起进行了分析。NGC 4631的垂直刻度高度在星系内的不同区域变化很大，在4.85 GHz的平均值为2.3 kpc（370 pc），厚（薄）盘高于迄今为止在其他六个边缘螺旋星系中发现的平均值。这可能起源于NGC 4631与其邻近星系的潮汐相互作用。晕中的总磁场强度与盘中的总磁场强度相当，而晕中的有序磁场强度似乎高于盘中的值。由此得到的旋转测量值分布表明NGC 4631具有大尺度规则磁场结构。尽管强法拉第去极化沿着银道面和强束流去极化之间的过渡区的磁盘和晕，我们的研究强烈表明，磁场取向沿着中央5-7 kpc的磁盘也是平面平行。因此，我们认为NGC 4631也有一个磁场结构平行于沿着其整个磁盘。
In order to clarify whether NGC 4631 has a unique magnetic field configuration in the central region along its disk, we present high-resolution Faraday-corrected polarization data. Radio continuum observations of NGC 4631 at 4.85 GHz were performed with the VLA. In addition, observations were made with the Effelsberg telescope at 4.85 GHz and at 8.35 GHz. These were analyzed together with archival VLA-data at 8.35 GHz. The vertical scale heights in NGC 4631 vary significantly in different regions within the galaxy and their mean values at 4.85 GHz are with 2.3 kpc (370 pc) for the thick (thin) disk higher than the mean values found so far in six other edge-on spiral galaxies. This may originate in the tidal interaction of NGC 4631 with its neighbouring galaxies. The total field strengths in the halo are of the order of the total magnetic field strength in the disk, whereas the ordered field strengths in the halo seem to be higher than the value in the disk. The derived distribution of rotation measures implies that NGC 4631 has a large-scale regular magnetic field configuration. Despite the strong Faraday depolarization along the galactic plane and the strong beam depolarization in the transition zone between the disk and halo, our research strongly indicates that the magnetic field orientation along the central 5-7 kpc of the disk is also plane-parallel. Therefore, we claim that NGC 4631 also has a magnetic field structure plane-parallel along its entire disk.