Reconnection Front Associated with Asymmetric Magnetic Reconnection: Particle-in-cell Simulations

Reconnection front (RF) has frequently been observed in the magnetotail and is well known as the dipolarization front in the near-Earth tail. Whether the RF exists in reconnection with distinct plasma/field properties across the reconnecting current sheet (i.e., asymmetric reconnection) is unknown yet. In this Letter, we use 2.5D particle-in-cell simulations to investigate the properties of RF in asymmetric reconnection and compare to RFs in symmetric reconnection. We find that RF is a robust structure in asymmetric reconnection. Its moving speed and thickness are smaller than those in symmetric reconnection. Its properties, such as the current density, electromagnetic field structure, are examined. Some features of RF in asymmetric reconnection are drastically different than those in symmetric reconnection. These results are of great help for studying RF in plasma environments with asymmetric reconnection, such as Earth's magnetopause.