A computational model for exploring particle acceleration during macroscale magnetic reconnection

A novel computational model for describing energetic electrons produced by magnetic reconnection in macroscale systems is developed and explored. It has long been known that magnetic reconnection in the solar corona produces a power law for high energy electrons (Lin & Hudson 1971; Emslie et al. 2004; Emslie et al. 2005). However, due to the extreme separation of scales, it is difficult to produce a model that can resolve the small scale structures near the x-line during reconnection and include the evolution of the global system. Fortunately, recent research suggests that the parallel electric field is an inefficient mechanism for acceleration; instead Fermi reflection is primarily responsible for the production of these electrons (Dahlin et al. 2015; 2016). By taking advantage of this discovery we can order out the small scale kinetic effects that are responsible for producing these electric fields. The resulting model has a magnetohydrodynamic (MHD) backbone with energetic electrons represented as macro-particles. These particles feed back onto the MHD equations ensuring overall energy conservation and, importantly, the equations correctly describe the firehose instability, which plays a crucial role in both throttling reconnection (Drake et al. 2006, Drake et al. 2010) and in controlling the spectral index of the energetic electrons (Drake et al. 2013). Simulation of energetic particles produced from reconnection are presented.