Strong electron heating and non-Maxwellian behavior in magnetic reconnection

We discuss the electron heating in the course of magnetic reconnection by using both the Geotail observation and the particle-in-cell simulation. Geotail observes several unique non-Maxwellian velocity distribution functions during the plasma sheet crossing in association with a fast plasma flow. We find that the observed distributions can be classified into four different types depending on the position in the plasma sheet. In the boundary between the lobe and the plasma sheet, the distribution consists of the cold plasma flowing toward the X-type region and the hot plasma escaping from the X-type region along the magnetic field. In the plasma sheet side of the boundary, the distribution becomes bi-Maxwellian distribution with T-parallel to > T-perpendicular to. Inside the plasma sheet, the distribution is deformed into a hot and isotropic distribution. We discuss the physical mechanism responsible for those electron heating in a thin plasma sheet by using the kinetic reconnection simulation. We find that the dawn-dusk reconnection electric field as well as the turbulent waves excited by the strong Hall electric currents play an important role on the strong electron heating and acceleration.