发表机构
Columbia University; Flatiron Institute（哥伦比亚大学; 平顿研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出解析理论并辅以PIC模拟，研究相对论电子-正电子-离子重联中能量分配，发现离子能量份额远低于均分假设，影响天体物理源的中微子辐射。
AI 中文摘要
相对论磁重联是粒子加速的主要机制，已在电子-离子等离子体和正负电子对等离子体中得到广泛研究，但在电子-正电子-离子等离子体中耗散能量如何在各粒子种类间分配，尤其是离子如何在以正负电子对为主导的层内被加速，仍知之甚少。我们发展了一个解析理论，将单粒子轨道动力学与集体等离子体响应耦合起来，并用跨越从正负电子对主导到电子-离子组成的粒子模拟（PIC）对其进行了验证。粒子在电场主导区域被直接加速，直到重联后的磁场将其偏转进入外流；特征逃逸长度由重联加热混合物的相对论趋肤深度决定，其中包含离子的贡献。设$\sigmastar$为每粒子可用的磁能（以$m_ec^2$为单位），$\mu=m_i/m_e$，则平均轻子能量按$\sigmastar$标度，而平均离子能量在离子从电场主导区域非相对论逃逸时按$\mu^{1/3}(\sigmastar)^{2/3}$标度，当离子逃逸为极端相对论时接近轻子能量。预测的能量分配比例在组分、质量比和磁化强度变化下均与模拟一致。离子在耗散能量中所占份额可能远低于通常假设的离子-轻子均分，从而减少了重联驱动的天体物理源中可用于强子辐射和中微子辐射的能量。
英文摘要
Relativistic magnetic reconnection, a prime mechanism for particle acceleration, has been extensively studied in electron--ion and pair plasmas, but how the dissipated energy is shared among species in electron--positron--ion plasmas, and in particular how ions are energized within a pair-dominated layer, remains poorly understood. We develop an analytic theory that couples single-particle orbit dynamics to the collective plasma response, and we validate it with particle-in-cell simulations spanning pair-dominated to electron--ion compositions. Particles are directly energized in electric-dominated regions until the reconnected magnetic field deflects them into the outflow; the characteristic escape length is in turn set by the relativistic skin depth of the reconnection-heated mixture, including the ion contribution. Writing $σ_e^*$ for the magnetic energy available per particle in units of $m_ec^2$ and $μ=m_i/m_e$, the mean lepton energy scales as $σ_e^*$, whereas the mean ion energy scales as $μ^{1/3}(σ_e^*)^{2/3}$ when ions escape non-relativistically from the electric-dominated regions and approaches the lepton energy when their escape is ultrarelativistic. The predicted energy fractions agree with simulations across composition, mass ratio, and magnetization. The ion share of the dissipated energy can fall far below the commonly assumed ion--lepton equipartition, reducing the energy available for hadronic and neutrino emission in reconnection-powered astrophysical sources.
Comments17 pages, 10 figures; includes End Matter and Supplemental Material
