Electron heating by magnetization and its application to dipolarization fronts in Earths magnetotail Theory, Simulations, and Observations

It has been suggested that high electron temperatures downstream of a magnetic reconnection site are associated with outflowing electron beams getting remagnetized by the strong reconnected field in a dipolarization front. This leads to a substantial increase in the perpendicular electron temperature as the remagnetized electrons form a ring distribution in the perpendicular velocity plane. In this study, we predict the major and minor radii of rings in terms of plasma conditions upstream of the reconnection site, then write analytical expressions for the electron temperature and the electron temperature anisotropy in terms of the ring major and minor radii. We test the validity of the theory with 2.5-dimension particle-in-cell simulations with varying upstream plasma density and temperature, finding excellent agreement for predicted ring major and minor radii and good agreement for electron temperature and perpendicular electron temperature anisotropy. Finally, we show THEMIS satellite observation of the highest electron temperature in a dipolarization front, revealing an electron ring distribution, and we assess the ring parameters of the observed ring distribution in the context of our model.