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arXiv 0908.3378astro-ph.GAastro-ph.IM
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来自银河系3D发射模型的模拟SKA图

Simulated SKA maps from Galactic 3D-emission models

X. H. Sun, W. Reich

摘要:

(节略)我们提出了各种银河系的地图和纬度在1.4 GHz,这是频率深SKA调查建议。地图大小约为1.5度,角分辨率约为1.6角秒。我们分析的地图,其概率密度函数(PDF)和结构功能。由于规则和随机磁场的不同贡献,总强度发射在平面上比在高纬度更平滑。高纬场的偏振辐射和辐射调制结构比平面上的偏振辐射和辐射调制结构要多,而平面上的偏振辐射和辐射调制结构主要是小尺度的斑片状辐射结构。在平面上的RM PDF接近高斯,但明显偏离高纬度。RM结构函数在高纬度地区振幅较小,斜率较陡。这些结果来自于这样一个事实,即更多的湍流细胞被平面上的视线穿过。虽然模拟的随机磁场分量是三维分布的,但从RM结构函数中提取的磁场谱在平面上符合二维,在高纬度地区接近三维。这部分与湍流磁场的外尺度有关,但主要与视线的不同长度有关。

英文摘要:

(Abridged) We present maps for various Galactic longitudes and latitudes at 1.4 GHz, which is the frequency where deep SKA surveys are proposed. The maps are about 1.5 deg in size and have an angular resolution of about 1.6 arcsec. We analyse the maps in terms of their probability density functions (PDFs) and structure functions. Total intensity emission is more smooth in the plane than at high latitudes due to the different contributions from the regular and random magnetic field. The high latitude fields show more extended polarized emission and RM structures than those in the plane, where patchy emission structures on very small scales dominate. The RM PDFs in the plane are close to Gaussians, but clearly deviate from that at high latitudes. The RM structure functions show smaller amplitudes and steeper slopes towards high latitudes. These results emerge from the fact that much more turbulent cells are passed through by the line-of-sights in the plane. Although the simulated random magnetic field components distribute in 3D, the magnetic field spectrum extracted from the structure functions of RMs conforms to 2D in the plane and approaches 3D at high latitudes. This is partly related to the outer scale of the turbulent magnetic field, but mainly to the different lengths of the line-of-sights.

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