A Model for Patchy Reconnection in Three Dimensions

We show, theoretically and via MHD simulations, how a short burst ofreconnection localized in three dimensions on a one-dimensional current sheetcreates a pair of reconnected flux tubes. We focus on the post-reconnectionevolution of these flux tubes, studying their velocities and shapes. We findthat slow-mode shocks propagate along these reconnected flux tubes, releasingmagnetic energy as in steady-state Petschek reconnection. The geometry of thesethree-dimensional shocks, however, differs dramatically from the classicaltwo-dimensional geometry. They propagate along the flux tube legs in fourisolated fronts, whereas in the two-dimensional Petschek model, they form acontinuous, stationary pair of V-shaped fronts. We find that the cross sections of these reconnected flux tubes appear asteardrop shaped bundles of flux propagating away from the reconnection site.Based on this, we argue that the descending coronal voids seen by Yohkoh SXT,LASCO, and TRACE are reconnected flux tubes descending from a flare site in thehigh corona, for example after a coronal mass ejection. In this model, theseflux tubes would then settle into equilibrium in the low corona, forming anarcade of post-flare coronal loops.Comment: 27 pages plus 16 figure