TWO-DIMENSIONAL PARTICLE-IN-CELL SIMULATIONS OF THE NONRESONANT, COSMIC-RAY-DRIVEN INSTABILITY IN SUPERNOVA REMNANT SHOCKS
TWO-DIMENSIONAL PARTICLE-IN-CELL SIMULATIONS OF THE NONRESONANT, COSMIC-RAY-DRIVEN INSTABILITY IN SUPERNOVA REMNANT SHOCKS
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DOI：
10.1088/0004-637x/698/1/445
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发表时间：
2008-12
期刊：
影响因子：
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通讯作者：
Y. Ohira;B. Reville;J. Kirk;F. Takahara
中科院分区：
文献类型：
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作者：
Y. Ohira;B. Reville;J. Kirk;F. Takahara
在超新星遗迹中，非碰撞冲击波上游磁场的非线性放大对于宇宙射线加速到1015.5 eV的“膝盖”能量至关重要。由宇宙射线电流驱动的非共振不稳定性被认为是造成这种效应的原因。我们进行二维，粒子在细胞模拟这种不稳定性。我们观察到的圆偏振非传播磁波的线性理论预测的初始增长。它表明，在某些情况下，在增长波的磁能密度可以增长到至少10倍，其初始值。我们没有发现竞争模式的证据，也没有发现热效应的显着改变。在晚些时候，我们观察到饱和的不稳定性的模拟，但负责的机制是一个人工制品的周期性边界条件，并没有对应的超新星冲击的情况。
In supernova remnants, the nonlinear amplification of magnetic fields upstream of collisionless shocks is essential for the acceleration of cosmic rays to the energy of the “knee” at 1015.5 eV. A nonresonant instability driven by the cosmic ray current is thought to be responsible for this effect. We perform two-dimensional, particle-in-cell simulations of this instability. We observe an initial growth of circularly polarized nonpropagating magnetic waves as predicted in linear theory. It is demonstrated that in some cases the magnetic energy density in the growing waves can grow to at least 10 times its initial value. We find no evidence of competing modes, nor of significant modification by thermal effects. At late times, we observe saturation of the instability in the simulation, but the mechanism responsible is an artifact of the periodic boundary conditions and has no counterpart in the supernova-shock scenario.