Fast magnetic reconnection in fluid models of collisionless pair plasma

The original studies of the GEM magnetic reconnection challenge problem exhibited fast magnetic reconnection in models which included Hall term effects. Subsequent PIC simulations showed that fast reconnection occurs even in pair plasmas, where the Hall term is absent; these studies attributed fast reconnection to nongyrotropic pressure. So we ask, (1) \emph{Can a model of pair plasma with isotropic pressure exhibit fast reconnection?}, and (2) \emph{Can a fluid model replicate patterns of fast magnetic reconnection seen in PIC simulations}? We have simulated the GEM problem for a pair plasma using ten-moment gas-dynamics for each species coupled to Maxwell's equations. Surprisingly, we find that the adiabatic collisionless ten-moment model gives slow reconnection but that isotropization \emph{increases} the rate of reconnection to typical fast rates. We hope to demonstrate fast reconnection in anisotropic pair plasma without direct isotropization by using a nonadiabatic closure for the generalized heat flux; in particular, we expect to report results for David Levermore's 10-moment closure.