10:45 AM - 11:00 AM
[PEM10-06] Study of slow-mode shock formation and particle acceleration in the symmetric magnetic reconnection based on hybrid simulations
Keywords:magnetic reconnection, slow-mode shocks, hybrid simulations
We studied the structure of the magnetic reconnection boundary by using 2.5D hybrid simulations. We used the six Rankine-Hugoniot conditions and the six specific conditions for slow-mode shocks, which are also used by in-situ satellite observations, to study the presence of slow-mode shocks. We observe that the reconnection boundary can be interpreted as a slow-mode shock from as close as ~9 λi (λi = ion inertial length) from the X-point. The detection of slow-mode shocks increases with the increasing distance from the X-point and with the increasing ion plasma beta. Additionally, it is observed that if the slow-mode shocks are analyzed by taking artificial satellite cuts at various angles, the detection percentage of slow-mode shocks can decrease to ~10% for very oblique crossings. The detection percentage of slow-mode shocks is the percentage of points out of the total points studied, where the slow-mode shocks were observed. At the point of incidence into the slow-mode shocks, the cold particles get accelerated and they gain energy. However, as we move further from the X-point, a non-classical picture of slow-mode shocks emerges, where the slow-mode shock downstream region has accelerated particles but they are not accelerated by the shock in its immediate vicinity. This accelerated crescent-shaped beam population is first accelerated at the slow-mode shock much closer to the X-point, and then it travels to the slow-mode shock downstream region further away from the X-point, gaining energy on the way by reflecting between the two slow-mode shocks. It was speculated by Wygant et al. [2005] that the electric field structure which causes the bounce of ions and leads to gain in energy could be slow-mode shock-like structure. Our simulations support that, since we observe that along with the reconnection electric field, the cross-shock electric field and thus, the slow-mode shocks play a role in reflection and acceleration of particles.