Electron acceleration with improved Stochastic Differential Equation method: Cutoff shape of electron distribution in test-particle limit
Electron acceleration with improved Stochastic Differential Equation method: Cutoff shape of electron distribution in test-particle limit
复制标题
改进的随机微分方程法的电子加速：测试粒子极限中电子分布的截止形状
DOI：
10.1016/j.jheap.2015.02.001
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发表时间：
2015
影响因子：
3.8
通讯作者：
Shohei Yanagita
中科院分区：
文献类型：
--
作者：
Ryo Yamazaki;Tatsuo Yoshida;Yuke Tsuchihashi;Ryosuke Nakajima;Yutaka Ohira;Shohei Yanagita
本文发展了一种随机微分方程方法来模拟电子在天体物理冲击下的加速过程。我们的方法是基于伊藤的随机微分方程耦合粒子分裂，采用斜布朗运动的非对称冲击交叉概率被认为是。利用该程序，我们模拟了不同参数下电子在静止平面平行激波上的加速过程，并研究了截止形状参数α表征的截止形状随扩散系数β的动量依赖性的变化。在年龄限制的情况下，我们复制了其他作者的先前结果，a α 2 β。在冷却受限的情况下，虽然我们认识到在某种程度上的偏差，但分析预期a β+ 1大致重现。在逃逸限制加速度的情况下，数值结果与解析定常解吻合较好，但偏离了已有的渐近解析公式α β。
We develop a method of stochastic differential equation to simulate electron acceleration at astrophysical shocks. Our method is based on Itô's stochastic differential equations coupled with a particle splitting, employing a skew Brownian motion where an asymmetric shock crossing probability is considered. Using this code, we perform simulations of electron acceleration at stationary plane parallel shock with various parameter sets, and studied how the cutoff shape, which is characterized by cutoff shape parameter a, changes with the momentum dependence of the diffusion coefficient β. In the age-limited cases, we reproduce previous results of other authors, a≈ 2 β. In the cooling-limited cases, the analytical expectation a≈ β+ 1 is roughly reproduced although we recognize deviations to some extent. In the case of escape-limited acceleration, numerical result fits analytical stationary solution well, but deviates from the previous asymptotic analytical formula a≈ β.