Reconnection Diffusion, Star Formation and Numerical Simulations

Abstract: We consider fast magnetic reconnection that takes place within turbulent magnetic flux and show that the process results in diffusion of magnetic fields and matter, which we term reconnection diffusion. The process of reconnection diffusion is based on the model of 3D reconnection of weakly turbulent magnetic fields and is applicable to both fully ionized and partially ionized gas. The rate of reconnection diffusion does not depend on the level of ionization and therefore the usually employed ambipolar diffusion idea gets irrelevant for magnetic field transport in turbulent fluids. We claim that the reconnection diffusion process is a manifestation of the violation of flux conservation in highly conducting turbulent fluids. We discuss the consequences of reconnection diffusion for star formation and stress. We show that reconnection diffusion on large scales is independent of small scale magnetic field dynamics of magnetic fields. We conclude that numerical simulations correctly represents the diffusion of actual astrophysical magnetic fields in flows with substantially larger Lundquist numbers if these simulated regions regions are turbulent.