标题： 低β对偶等离子体磁重联中的粒子加速 显示英文标题

标题： Particle Acceleration during Magnetic Reconnection in a Low-beta Pair Plasma

摘要： 在以低等离子体β值（$\beta = 8 \pi nkT_0/B^2 \ll 1$）和/或高磁化率（$\sigma = B^2/(4 \pi nmc^2) \gg 1$）为特征的磁主导态中，磁场重联驱动的等离子体加速在太阳耀斑、脉冲星风星云以及黑洞相对论喷流等一系列天体物理系统中具有重要意义。 本文回顾了这一过程的动能模拟最新进展，并进一步讨论了由电子-正电子对组成的低$\beta$重联层中的等离子体动力学和粒子加速。 我们还研究了不同初始热温度对最终粒子能量谱的影响。 虽然早期的研究表明，对于更高的$\sigma$，光谱指数较小，但我们的模拟显示，当等离子体的$\beta$足够低时，即使$\sigma \sim 1$，光谱指数接近$p=1$。由于在这种理想极限下的预测光谱指数比大多数观测结果更硬，因此有必要考虑可能导致较软光谱的因素，例如开放边界模拟。 我们还指出，在未来需要解决三维重联物理和湍流对重联的影响。 显示英文摘要

摘要： Plasma energization through magnetic reconnection in the magnetically-dominated regime featured by low plasma beta ($\beta = 8 \pi nkT_0/B^2 \ll 1$) and/or high magnetization ($\sigma = B^2/(4 \pi nmc^2) \gg 1$) is important in a series of astrophysical systems such as solar flares, pulsar wind nebula, and relativistic jets from black holes, etc. In this paper, we review the recent progress on kinetic simulations of this process and further discuss plasma dynamics and particle acceleration in a low-$\beta$ reconnection layer that consists of electron-positron pairs. We also examine the effect of different initial thermal temperatures on the resulting particle energy spectra. While earlier papers have concluded that the spectral index is smaller for higher $\sigma$, our simulations show that the spectral index approaches $p=1$ for sufficiently low plasma $\beta$, even if $\sigma \sim 1$. Since this predicted spectral index in the idealized limit is harder than most observations, it is important to consider effects that can lead to a softer spectrum such as open boundary simulations. We also remark that the effects of 3D reconnection physics and turbulence on reconnection need to be addressed in the future.