The Variable Rotation Measure Distribution in 3C 273 on Parsec Scales
The Variable Rotation Measure Distribution in 3C 273 on Parsec Scales
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秒差距尺度上 3C 273 中的可变旋转测量分布
DOI：
10.3390/galaxies6010005
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
J. Wardle
中科院分区：
文献类型：
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作者：
J. Wardle
我们简要回顾了同步辐射喷流中不透明度如何影响观测到的偏振。我们给出了1999-2000年利用VLBA对3C273进行的一些新的多频观测，这些观测大大增加了该源的现有旋转测量(RM)观测。我们的发现可以概括如下：(1)Rm的横向梯度得到了充分的证实。这意味着磁场中有一个环形分量，这反过来需要1017-1018A的电流从射流中流下。(2)喷流中的净磁场是纵向的，但纵向分量是否为矢量有序是一个悬而未决的问题。(3)Rm分布在几个月到几年的时间尺度上是可变的。我们将其归因于围绕喷流的法拉第屏后面的超光速分量的运动。(4)最后，我们认为，利用Event Horizon望远镜在更高分辨率和更高频率下测量Faraday旋转，可以对中心黑洞的吸积率施加有用的限制。
We briefly review how opacity affects the observed polarization in synchrotron emitting jets. We show some new multi-frequency observations of 3C 273 made with the VLBA in 1999–2000, which add significantly to the available rotation measure (RM) observations of this source. Our findings can be summarized as follows: (1) The transverse gradient in RM is amply confirmed. This implies a toroidal component to the magnetic field, which in turn requires a current of 1017–1018 A flowing down the jet. (2) The net magnetic field in the jet is longitudinal; however, whether or not the longitudinal component is vector-ordered is an open question. (3) The RM distribution is variable on timescales of months to years. We attribute this to the motion of superluminal components behind a turbulent Faraday screen that surrounds the jet. (4) Finally, we suggest that Faraday rotation measurements at higher resolution and higher frequencies, with the Event Horizon Telescope, may enable useful constraints to be placed on the accretion rate onto the central black hole.