STRUCTURE IN THE ROTATION MEASURE SKY
STRUCTURE IN THE ROTATION MEASURE SKY
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DOI：
10.1088/0004-637x/726/1/4
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发表时间：
2010-10
期刊：
影响因子：
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通讯作者：
J. Stil;A. Taylor;C. Sunstrum
中科院分区：
文献类型：
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作者：
J. Stil;A. Taylor;C. Sunstrum
本文根据Taylor等人的旋转测度星表，分析了天空的旋转测度结构。几个已解析的RM结构与当地星际介质中的结构一致，包括射电环I、II和III、树胶星云和猎户座-波江座超级气泡。给出了选定区域的RM结构函数，并将其振幅和斜率图与Hα强度和漫射偏振强度图进行了比较。角标度为1°的RM方差与通过银河系的视线长度相关，并有局部结构的贡献。SFs的斜率不太集中于银河平面，并且与通过银河系的视线长度相关性较小，这表明RM结构在角尺度上的起源更接近于10°。南银河系极点的RM方差比北银河系极点高出1.02倍，反映了银河系北方半球和南半球之间更广泛的不对称性。在纬度<30°的银河系扩散同步辐射的退偏振可以在很大程度上用与RM的小尺度变化相关的法拉第色散来解释，但是误差允许来自沿着视线的差分法拉第旋转的显著贡献。
An analysis of structure in rotation measure (RM) across the sky based on the RM catalog of Taylor et al. is presented. Several resolved RM structures are identified with structure in the local interstellar medium, including radio loops I, II, and III, the Gum nebula, and the Orion–Eridanus superbubble. Structure functions (SFs) of RM are presented for selected areas, and maps of SF amplitude and slope across the sky are compared with Hα intensity and diffuse polarized intensity. RM variance on an angular scale of 1° is correlated with length of the line of sight through the Galaxy, with a contribution from local structures. The slope of the SFs is less concentrated to the Galactic plane and less correlated with length of the line of sight through the Galaxy, suggesting a more local origin for RM structure on angular scales ∼10°. The RM variance is a factor of ∼2 higher toward the South Galactic Pole than toward the North Galactic Pole, reflecting a more wide-spread asymmetry between the northern and southern Galactic hemispheres. Depolarization of diffuse Galactic synchrotron emission at latitudes <30° can be explained largely by Faraday dispersion related to small-scale variance in RM, but the errors allow a significant contribution from differential Faraday rotation along the line of sight.