Plasmoid statistics in relativistic magnetic reconnection
Plasmoid statistics in relativistic magnetic reconnection
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DOI：
10.1093/mnras/sty033
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发表时间：
2017-10
影响因子：
4.8
通讯作者：
M. Petropoulou;I. Christie;L. Sironi;D. Giannios
中科院分区：
文献类型：
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作者：
M. Petropoulou;I. Christie;L. Sironi;D. Giannios
等离子体团是包含磁场和高能粒子的等离子体的准球形区域，是相对论状态中重联过程的自洽副产品。最近的二维细胞内粒子（PIC）模拟表明，等离子体团可以在重新连接层内经历各种过程（例如合并、整体加速、生长和平流）。我们开发了蒙特卡罗 (MC) 代码，以最近的 PIC 模拟为基准，以检查这些过程对等离子体链的稳态尺寸和动量分布的影响。差分等离子体尺寸分布显示为幂律 $N(w)\propto w^{-\chi}$，范围从几个等离子体趋肤深度到 $\sim 0.1$ 重联层长度。我们通过数值和分析证明，幂律斜率 $\chi$ 与等离子体加速度和增长率之比线性相关，并且随着等离子体磁化强度的增加（从 3 到 50），幂律斜率略有下降（从 $\sim 2$ 到 $\sim 1.3$）。我们将我们的结果与最近的 PIC 模拟结果进行了详细比较，并通过耀变喷流耀斑事件的代表性案例简要讨论了我们的发现的天体物理学意义。
Plasmoids, quasi-spherical regions of plasma containing magnetic fields and high-energy particles, are a self-consistent by-product of the reconnection process in the relativistic regime. Recent two-dimensional particle-in-cell (PIC) simulations have shown that plasmoids can undergo a variety of processes (e.g. mergers, bulk acceleration, growth, and advection) within the reconnection layer. We developed a Monte Carlo (MC) code, benchmarked with the recent PIC simulations, to examine the effects of these processes on the steady-state size and momentum distributions of the plasmoid chain. The differential plasmoid size distribution is shown to be a power law, $N(w)\propto w^{-\chi}$, ranging from a few plasma skin depths to $\sim 0.1$ of the reconnection layer's length. We demonstrate numerically and analytically that the power law slope $\chi$ is linearly dependent upon the ratio of the plasmoid acceleration and growth rates and that it slightly decreases (from $\sim 2$ to $\sim 1.3$) with increasing plasma magnetization (from 3 to 50). We perform a detailed comparison of our results with those of recent PIC simulations and briefly discuss the astrophysical implications of our findings through the representative case of flaring events from blazar jets.