MHD turbulence in the very local interstellar medium and the IBEX ribbon*

We investigate the role of the magnetohydrodynamic (MHD) turbulence measured by Voyager in the very local interstellar medium (VLISM) in modeling the Interstellar Boundary Explorer ({it IBEX}) ribbon. We demonstrate that the mirroring by compressible modes of MHD turbulence dominates over that by the mean magnetic field. Based on the new mirror diffusion mechanism identified by Lazarian & Xu 2021 for particles with large pitch angles in MHD turbulence, we find that the mirror diffusion can efficiently confine pickup ions and cause their enhanced intensity. The ribbon width is determined by both the range of pitch angles for effective turbulent mirroring and the field line wandering induced by Alfv'{e}nic modes. The field line wandering also affects the coherence of the ribbon structure across the sky. By extrapolating the magnetic energy spectrum measured by Voyager, we find that the injection scale of the turbulence in the VLISM is less than $sim 500$ au for the ribbon structure to be coherent.