Exact solutions for two-dimensional steady state magnetic reconnection in partially ionized plasmas

In this paper we present a family of exact solutions for the problem of two-dimensional steady state magnetic reconnection in incompressible, partially ionized plasmas, incorporating previous analytical solutions for the fully ionized case. For our purpose we use a two-fluid model with the ion-neutral collision drag included. The ionization and recombination processes are assumed to be balanced. The solutions yield a variety of reconnection patterns for shearing flows and shearing magnetic field lines, assuming no inherent topological symmetry for the geometry. From these patterns it is shown that magnetic field lines moving with ions slip into the diffusion region through neutrals. The analytical expressions for pressures of both ions and neutrals are given. For the solar photosphere the ion-neutral drag is very large (strong coupling). Nevertheless, such a strong-coupling case makes it possible for us to express the solution analytically. The solution shows that fast magnetic reconnection can also occur in the solar photosphere, supporting the reconnection explanation for the magnetic flux cancellation and type II white-light flares.