Guo Fan, Li Hui, Daughton William, Liu Yi-Hsin
Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, USA.
Phys Rev Lett. 2014 Oct 10;113(15):155005. doi: 10.1103/PhysRevLett.113.155005. Epub 2014 Oct 8.
Using fully kinetic simulations, we demonstrate that magnetic reconnection in relativistic plasmas is highly efficient at accelerating particles through a first-order Fermi process resulting from the curvature drift of particles in the direction of the electric field induced by the relativistic flows. This mechanism gives rise to the formation of hard power-law spectra in parameter regimes where the energy density in the reconnecting field exceeds the rest mass energy density σ ≡ B(2)/(4πnm(e)c(2))>1 and when the system size is sufficiently large. In the limit σ ≫ 1, the spectral index approaches p = 1 and most of the available energy is converted into nonthermal particles. A simple analytic model is proposed which explains these key features and predicts a general condition under which hard power-law spectra will be generated from magnetic reconnection.
通过全动力学模拟，我们证明相对论性等离子体中的磁重联在通过一阶费米过程加速粒子方面非常高效，该过程源于粒子在相对论流感应电场方向上的曲率漂移。在重联场中的能量密度超过静止质量能量密度σ≡B²/(4πnmₑc²)>1且系统尺寸足够大的参数区域中，这种机制会导致硬幂律谱的形成。在σ≫1的极限情况下，谱指数接近p = 1，并且大部分可用能量会转化为非热粒子。我们提出了一个简单的解析模型，该模型解释了这些关键特征，并预测了磁重联将产生硬幂律谱的一般条件。
