Kinetic Simulation of Magnetic Reconnection with Pickup Ions: Shell Stability and Reconnection Rate Analysis

Collisionless magnetic reconnection is postulated to be active in many regions of the heliosphere, where the physics and formation of heliospheric structures are influenced by pickup ions (PUIs). Recent investigations suggest that the presence of PUIs may enhance the reconnection rate due to PUI-induced turbulence. Our investigation from particle-in-cell simulations with seed PUI shell velocity distributions reveals that the distributions remain quasi-stable within the reconnection exhaust region. The reconnection rate is rather suppressed as compared with non-PUI reconnection simulations. The PUI population eventually responds to the reconnection dynamics and forms a thicker current sheet layer. Both PUI and regular ion populations develop sub-ion-Alfvénic outflow jets, although PUI outflows are slower in comparison and extend beyond the separatrix surface. We predict that a future Interstellar Probe mission may encounter reconnecting current sheet layers in the outer heliosphere that demonstrate an initial slow modulation followed by a sharp rotation of the reconnecting magnetic field toward the center of the layer.