The Scaling of Asymmetric Relativistic Magnetic Reconnection: Theory and Simulations

Magnetic reconnection is often invoked to explain impulsive non-thermal particle acceleration in highly magnetized astrophysical systems. However, to date, the corresponding theory for relativistic reconnection has only been developed for symmetric inflow conditions, i.e., symmetric density, temperature and field strength, despite the ubiquity of asymmetric reconnection in space and laboratory plasmas. To address this, we derive basic scaling equations for relativistic magnetic reconnection with asymmetric inflow conditions and obtain a prediction for the relativistic outflow velocity. Kinetic Particle-in-Cell simulations are used to verify the scaling predictions for the characteristics of the outflow jet. Additionally, we show that the spectral index of the non-thermal particles accelerated by magnetic reconnection is constrained by the inflowing plasma with the lower magnetization, in agreement with the scaling predictions. These results have important implications for the role of magnetic reconnection in astrophysical systems and for the non-thermal spectra produced by magnetic reconnection.