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arXiv 0903.1259astro-ph.HE
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巨射电星系叶中的随机粒子加速

Stochastic particle acceleration in the lobes of giant radio galaxies

S. O'Sullivan, B. Reville, A. M. Taylor

摘要:

本文研究了巨射电星系叶中粒子通过二级费米过程的加速。这些地点是超高能宇宙射线加速器的候选者。我们聚焦于附近的FR I射电星系半人马座A。这是由于它的位置与几个最高能量俄歇事件的到达方向重合。与准线性理论预测的加速时标一致的必要条件进行了审查。在保证电场没有与局部磁场平行的分量的场中进行测试粒子计算。准线性理论的结果,数量级,被发现是准确的,在低湍流水平的非相对论阿尔芬波和低和高湍流水平的温和相对论的情况下。我们的结论是,纯随机加速是合理的超高能宇宙射线在半人马座A的发生器,重子数密度将需要几个数量级低于目前持有的上限。

英文摘要:

We investigate the acceleration of particles via the second-order Fermi process in the lobes of giant radio galaxies. Such sites are candidates for the accelerators of ultra-high energy cosmic rays. We focus on the nearby FR I radio galaxy Centaurus A. This is motivated by the coincidence of its position with the arrival direction of several of the highest energy Auger events. The conditions necessary for consistency with the acceleration timescales predicted by quasi-linear theory are reviewed. Test particle calculations are performed in fields which guarantee electric fields with no component parallel to the local magnetic field. The results of quasilinear theory are, to order of magnitude, found to be accurate at low turbulence levels for non-relativistic Alfven waves and at both low and high turbulence levels in the mildly relativistic case. We conclude that for pure stochastic acceleration to be plausible as the generator of ultra-high energy cosmic rays in Centaurus A, the baryon number density would need to be several orders of magnitude below currently held upper-limits.

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