Reconnection signatures in Kelvin–Helmholtz instability evolution in 2D PIC simulations

We performed 2D PIC simulations of Kelvin–Helmholtz instability (KHI) with symmetric and asymmetric density and temperature profiles along the flow shear with primarily a northward interplanetary magnetic field with a small uniform in-plane field. The aim of this study is to understand the role and degree of magnetic reconnection in the evolution of the KHI. We use the magnetic flux transport method, field topology, and magnetic field minima to identify the reconnection X-lines. Magnetic reconnection signatures along with flow reversals at the vortex edges start to appear in the nonlinear phase of the KHI after the vortices have begun rolling up. The number of reconnection regions increases until turbulence develops. The signatures eventually decrease and finally disappear at the late stages of KHI. Our results qualitatively agree with MMS observations of reconnection signatures at the KHI, decreasing by distance, along the magnetospheric flanks.