Synchrotron and inverse-Compton emission from radio galaxies with non-uniform magnetic field and electron distributions
Synchrotron and inverse-Compton emission from radio galaxies with non-uniform magnetic field and electron distributions
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具有不均匀磁场和电子分布的射电星系的同步加速器和逆康普顿发射
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发表时间：
2013
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通讯作者：
M. Hardcastle
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作者：
M. Hardcastle
我研究了射电星系扩展结构中的不均匀磁场对观测到的同步加速器和逆康普顿发射的影响。在各向同性场的假设下，在给定的功率谱和磁场强度的笛卡尔分量的高斯分布的情况下，我导出了一个简单的积分，可用于数值计算任何电子布居的同步加速器发射率。在幂律光谱的情况下，我表明可以估计具有这种场的区域的同步加速器发射率与通常假设的布置（其中 B 处处恒定，尽管完全缠结）的同步加速器发射率之间的差异，并且这种差异很小，尽管如果电子能量密度随场缩放，这种差异会增加。这种场中的老化电子能谱会产生特征性的弯曲同步加速器能谱，该谱与经典的贾菲-佩罗拉能谱显着不同，我讨论了这可能对标准能谱年龄拟合产生的一些影响。最后，我证明了宇宙微波背景的逆康普顿散射仅受到这种场结构的适度影响，如果电子跟随场，则影响变得更加重要。如果磁场不均匀但各向同性，文献中结合同步加速器和逆康普顿模型的磁场估计将给出平均磁场能量密度的合理估计。
I investigate the effect of non-uniform magnetic fields in th e extended structures of radio galaxies on the observed synchrotron and inverse-Compton emission. On the assumption of an isotropic field, with a given power spectrum and a Gaussian distribution of the Cartesian components of the magnetic field strength, I derive a simple i ntegral that can be used numerically to calculate the synchrotron emissivity from any electron population. In the case of power-law spectra, I show that it is possible to estimate the difference between the synchrotron emissivity from a region with such a field and that from the com monly assumed arrangement where B is constant everywhere, though fully tangled, and that this difference is small, though it increases if the electron energy density scales with the fi eld. An aged electron spectrum in such a field produces a characteristic curved synchrotron sp ectrum which differs significantly from the classical Jaffe-Perola spectrum, and I discuss some effects that this might have on standard spectral age fitting. Finally, I show that inverse- Compton scattering of the cosmic microwave background is only moderately affected by such a fi eld structure, with the effects becoming more important if the electrons follow the field. Ma gnetic-field estimates in the literature from combined synchrotron and inverse-Compton modelling will give reasonable estimates of the mean magnetic field energy density if the fiel d is non-uniform but isotropic.