论文标题
扩散冲击加速度的微物理学：对加速颗粒光谱的影响
Microphysics of diffusive shock acceleration: impact on the spectrum of accelerated particles
论文作者
论文摘要
无碰撞冲击的扩散冲击加速度仍然是在各种天体物理来源中加速颗粒的最可能过程。尽管强烈冲击的标准预测是加速粒子的光谱是通用的，$ f（p）\ propto p^{ - 4} $，但许多现象会影响这个简单的结论。通常，加速颗粒的非线性动力反应导致凹形光谱，比$ p^{ - 4} $陡峭，在Momenta低于几十GEV/C以下，并且比高能量下的标准预测更难。但是，在存在磁场放大的情况下，非线性效应变得很重要，进而导致最大动量$ p_ {max} $的较高值。最近发现，在向下推进时，增强粒子散射的自我生成的扰动沿与背景等离子体相同的方向移动，从而使电击时的有效压缩因子降低并且光谱变得更陡。我们研究了非谐振流不稳定性对这些光谱变形的激发的含义，光谱陡峭对冲击速度的依赖性以及注入动量所起的作用。
Diffusive shock acceleration at collisionless shocks remains the most likely process for accelerating particles in a variety of astrophysical sources. While the standard prediction for strong shocks is that the spectrum of accelerated particles is universal, $f(p)\propto p^{-4}$, numerous phenomena affect this simple conclusion. In general, the non-linear dynamical reaction of accelerated particles leads to a concave spectrum, steeper than $p^{-4}$ at momenta below a few tens of GeV/c and harder than the standard prediction at high energies. However, the non-linear effects become important in the presence of magnetic field amplification, which in turn leads to higher values of the maximum momentum $p_{max}$. It was recently discovered that the self-generated perturbations that enhance particle scattering, when advected downstream, move in the same direction as the background plasma, so that the effective compression factor at the shock decreases and the spectrum becomes steeper. We investigate the implications of the excitation of the non-resonant streaming instability on these spectral deformations, the dependence of the spectral steepening on the shock velocity and the role played by the injection momentum.
