Statistical Study on Electron and Ion Temperatures in the Near-Earth Reconnection and Magnetic Pileup Regions

Plasma heating during the magnetic reconnection is not well understood, particularly in terms of adiabaticity, heating rate, and electron-ion temperature ratio. This study focuses on macroscopic profiles of T-i, T-e, and T-i/T-e in the near-Earth magnetotail, using data obtained from Magnetospheric Multiscale. Observation points are categorized into three different regions: low-beta/high-beta inflow region, the reconnection sites, and magnetic pileup regions. From low-beta inflow region to high-beta inflow region, both T-i and T-e increase and electron entropy is constant. Ion entropy, on the other hand, increases across the transition. Inside the reconnection site, T-i and T-e increase, and entropies remain constant. From the outflow region to the pileup region, electrons are selectively heated. Electron entropy increases in the transition. This statistical study suggests that nonadiabatic heating occurs around the plasma sheet boundary layer for ions and at the early stage of magnetic field pileup for electrons.