Energetic spectra of relativistic reconnection at large scales.

The energetic particle spectra obtained from magnetic reconnection in the relativistic magnetically dominated regime, where the magnetization $sigma gg 1$, is studied using 2D particle-in-cell (PIC) simulations at large scales. For moderate magnetizations, where there is a significant scale difference between ions and electrons, it is possible to study larger systems using semi-implicit methods. One can take advantage of the stability of such numerical methods and increase the system size by under-resolving the smallest electron-scale physics. We explore the potential of these methods and compare with explicit PIC simulations, considering both computational advantages and the role of electron-scale physics and how well it must be resolved. While a large body of research has investigated the energetic particle spectra that is generated as a result of reconnection in such relativistic systems, the mechanism remains under debate. Understanding the differences in the energetic particle spectra at large scales, may help shed light on this debate, and provide more accurate spectra to compare with astronomical observations.