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arXiv 1105.0130astro-ph.HE
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宇宙粒子加速源中的磁场

Magnetic fields in cosmic particle acceleration sources

Andrei M. Bykov, Donald C. Ellison, Matthieu Renaud

摘要:

本文综述了天体物理粒子加速器中与超新星遗迹、射电星系和星系团中的无碰撞激波有关的一些磁现象。一个特殊的特点是加速粒子可以在物体的磁场演化中起重要作用。我们讨论了一些CR驱动的,磁场放大过程,可能会操作时,扩散冲击加速(DSA)变得有效和非线性。这些过程产生的湍流磁场决定了加速粒子的最大能量,并导致观测到的源光子辐射的特定特征。同样重要的是,如果激波是一个有效的CR加速器,CR电流和压力各向异性对磁场的放大可能会影响激波前体和下游气流中的激波气体温度和压缩。强波动的磁场以上的辐射形成的长度在冲击附近的尺度上的结果在间歇性结构中观察到的同步辐射图像。冲击波前兆中的共振和非共振CR流不稳定性可以产生中尺度磁场,其尺度大小与超新星遗迹甚至超级气泡相当。这开启了一种可能性,即最早期星系中的磁场是由第一代第三星族超新星遗迹和恒星形成区的成簇超新星产生的。

英文摘要:

We review here some magnetic phenomena in astrophysical particle accelerators associated with collisionless shocks in supernova remnants, radio galaxies and clusters of galaxies. A specific feature is that the accelerated particles can play an important role in magnetic field evolution in the objects. We discuss a number of CR-driven, magnetic field amplification processes that are likely to operate when diffusive shock acceleration (DSA) becomes efficient and nonlinear. The turbulent magnetic fields produced by these processes determine the maximum energies of accelerated particles and result in specific features in the observed photon radiation of the sources. Equally important, magnetic field amplification by the CR currents and pressure anisotropies may affect the shocked gas temperatures and compression, both in the shock precursor and in the downstream flow, if the shock is an efficient CR accelerator. Strong fluctuations of the magnetic field on scales above the radiation formation length in the shock vicinity result in intermittent structures observable in synchrotron emission images. Resonant and non-resonant CR streaming instabilities in the shock precursor can generate mesoscale magnetic fields with scale-sizes comparable to supernova remnants and even superbubbles. This opens the possibility that magnetic fields in the earliest galaxies were produced by the first generation Population III supernova remnants and by clustered supernovae in star forming regions.

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