半人马座A射电巨瓣中千秒差距尺度的法拉第旋转结构
Faraday Rotation Structure on Kiloparsec Scales in the Giant Radio Lobes of Centaurus A
摘要：
我们提出的结果，澳大利亚望远镜紧凑阵列1.4 GHz的分光偏振孔径合成调查的34平方度中心的半人马座A-NGC 5128。一个目录中的1005河外致密射电源在现场的连续通量密度为3毫焦耳/光束提供了一个表的法拉第旋转措施（RM）和线性偏振强度的28%的来源，高信号噪声的线性偏振。我们使用281个背景偏振源的集合作为半人马座A巨大射电瓣结构的视线探针。这是第一次这样的方法已被应用到无线电星系叶，我们解释它是如何不同于传统的方法，往往是复杂的深度和光束去极化效应。我们使用RM结构函数分析，并报告了一个湍流RM信号的检测，均方根为17 rad/m^2，尺度大小为0.3度，与南巨瓣有关。我们无法证实这种信号是来自整个叶的湍流结构，还是仅来自边缘周围的薄皮（或鞘），尽管我们倾向于后者。RM信号被建模为可能产生于一个薄的皮肤与热等离子体密度相当于半人马座群内介质密度和相干磁场，扭转其符号上的空间尺度为20千秒差距。
英文摘要：
We present the results of an Australia Telescope Compact Array 1.4 GHz spectropolarimetric aperture synthesis survey of 34 square degrees centred on Centaurus A - NGC 5128. A catalogue of 1005 extragalactic compact radio sources in the field to a continuum flux density of 3 mJy/beam is provided along with a table of Faraday rotation measures (RMs) and linear polarised intensities for the 28 percent of sources with high signal-to-noise in linear polarisation. We use the ensemble of 281 background polarised sources as line-of-sight probes of the structure of the giant radio lobes of Centaurus A. This is the first time such a method has been applied to radio galaxy lobes and we explain how it differs from the conventional methods that are often complicated by depth and beam depolarisation effects. We use an RM structure function analysis and report the detection of a turbulent RM signal, with rms of 17 rad/m^2 and scale size 0.3 degrees, associated with the southern giant lobe. We cannot verify whether this signal arises from turbulent structure throughout the lobe or only in a thin skin (or sheath) around the edge, although we favour the latter. The RM signal is modelled as possibly arising from a thin skin with a thermal plasma density equivalent to the Centaurus intragroup medium density and a coherent magnetic field that reverses its sign on a spatial scale of 20 kpc.
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