Nonmonotonic dependence of the microscopic reconnection rate on electron temperature in electron-only magnetic reconnection

Magnetospheric substorms are among the most intense energy release phenomena in Earth's magnetosphere. Magnetic reconnection in the magnetotail is their core mechanism. In most studies, thermal pressure effects on the reconnection rate have been neglected due to low plasma β. However, in electron-only reconnection, electron thermal pressure significantly modifies the reconnection rate even at low β. Here, we combine an analytical framework with three-dimensional particle-in-cell simulations of laser-driven electron-only reconnection. Within the magnetotail-relevant range of 650–850 eV, the microscopic reconnection rate exhibits a robust nonmonotonic dependence on electron temperature, peaking at 0.6 near 750 eV. This arises from competition between enhanced thermal transport promoting inflow at lower temperatures and diffusion-region broadening suppressing inflow at higher temperatures. Simulations with guide fields from 0.1 B0 to B0 confirm the robustness of the qualitative nonmonotonic trend. These results suggest that electron temperature is not merely a passive consequence of energy dissipation but an active regulator of reconnection dynamics.