Fast Magnetic Reconnection Induced by Resistivity Gradient in Resistive Magnetohydrodynamics (MHD) Simulations

Abstract:

Two-dimensional magnetohydrodynamics (MHD) simulations show that (1)Petschek reconnection is unstable using a uniform resistivity. (2)To achieve a Petschek-like fast reconnection in resistive MHD, it requires a localized resistivity. In this work, we show that a steady-state Petschek-like reconnection also develops in the transition region of a hyperbolic tangent resistivity profile. Our study further suggests that the gradient of resistivity along the outflow direction is the key ingredient in making Petschek reconnection accessible, supporting the idea proposed by Kulsurd (2001). Such a resistivity profile may happen in the lower solar atmosphere where the plasmas are highly stratified; the application of this study in modeling solar spicules will be discussed.