Formation of dipolarization fronts inside reconnection diffusion region
Résumé
For the first time, dipolarization fronts (DFs) are observed inside reconnection diffusion region, where the obstruction of reconnection jets by pre-existing plasmas is very weak. Also observed are whistlers at the DFs and magnetic island near the X-line. We find that the whistlers at the Earthward DF are much intenser than the whistlers at the tailward DF, as the electron temperature at the Earthward DF is more anisotropic (T⊥ > T//). This observation provides the first in situ evidence of previous simulation results that DFs can be produced by transient reconnection. We also discuss other generation mechanisms of DFs in this letter. The discovery of DFs inside reconnection diffusion region is important because the DF structure may provide a favorable condition for accelerating suprathermal electrons there.