Distribution of Negative J center dot E ' in the Inflow Edge of the Inner Electron Diffusion Region During Tail Magnetic Reconnection: Simulations Vs. Observations

Magnetic reconnection is a universal phenomenon existing in the space. Energy conversion is one of the essential parts of reconnection discussed for decades. Positive energy conversion (J center dot E ' > 0) is usually regarded as the sign of electron diffusion region (EDR), while the negative one (J center dot E ' < 0) turns out to gather in the outer EDR. Here we report the negative J center dot E ' appearing in the inflow edge of the inner EDR, based on Magnetospheric Multiscale mission observations and particle-in-cell simulations. Both observations and simulations verify that this negative J center dot E ' is mainly contributed from the electron pressure tensor term in generalized Ohm's law. The energy loss of electrons plays the dominant effect in the electron pressure tensor, and this energy decline is caused by the electric field which is induced by the decreasing magnetic field. Our results provide significant insights to expand the understanding of the reconnection regimes.