Characteristics of the structure in the Galactic polarized radio background at 350 MHz
Characteristics of the structure in the Galactic polarized radio background at 350 MHz
复制标题
350 MHz 银河偏振射电背景中的结构特征
DOI：
--
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Astron
中科院分区：
文献类型：
--
作者：
M. Haverkorn;P. Katgert;A. G. D. B. Leiden;Netherlands.;Astron
根据三组射电偏振观测资料，导出了斯托克斯参数Q、U和偏振强度P的角功率谱和结构函数。两个观察到的领域已在多个频率进行了研究，允许确定的功率谱和结构函数的旋转措施RM。第三个场覆盖了北方天空的很大一部分，因此可以研究银河系经纬度上功率谱的变化。Q和U的功率谱比P的更陡，可能是因为前景的法拉第屏在Q和U中产生了额外的结构，而在P中没有。Q和U中的额外结构发生在大尺度上，因此导致了更陡的谱。P的功率谱的导出斜率是多极谱指数alpha（P），并且与早期的估计一致。多极光谱指数α（P）随银河系纬度而减小（即光谱变得更平坦），但在银河系经度上与一个恒定值一致。旋转测度RM的功率谱表明谱指数α（RM）近似为1，而RM的结构函数近似为平坦的.结构函数是平坦的比早期的估计，从极化河外源，这可能是由于这样的事实，河外源RM探测整个视线通过银河系，而作为一个结果，去极化扩散无线电极化只探测附近的ISM。
Angular power spectra and structure functions of the Stokes parameters Q and U and polarized intensity P are derived from three sets of radio polarimetric observations. Two of the observed fields have been studied at multiple frequencies, allowing determination of power spectra and structure functions of rotation measure RM as well. The third field extends over a large part of the northern sky, so that the variation of the power spectra over Galactic latitude and longitude can be studied. The power spectra of Q and U are steeper than those of P, probably because a foreground Faraday screen creates extra structure in Q and U, but not in P. The extra structure in Q and U occurs on large scales, and therefore causes a steeper spectrum. The derived slope of the power spectrum of P is the multipole spectral index alpha(P), and is consistent with earlier estimates. The multipole spectral index alpha(P) decreases with Galactic latitude (i.e. the spectrum becomes flatter), but is consistent with a constant value over Galactic longitude. Power spectra of the rotation measure RM show a spectral index alpha(RM) approximate to 1, while the structure function of RM is approximately flat. The structure function is flatter than earlier estimates from polarized extragalactic sources, which could be due to the fact that extragalactic source RM probes the complete line of sight through the Galaxy, whereas as a result of depolarization diffuse radio polarization only probes the nearby ISM.