Regions associated with electron physics in asymmetric magnetic field reconnection

Abstract

[1] Spatial relationships between regions containing signatures of electron physics in asymmetric reconnection with a guide field are examined using simulations and space observations that are in excellent agreement. These electron physics regions do not completely overlap, are not confined to sizes - electron skin depth, and do not surround the X-line. The electron ideal Ohm's law, E + Ue × B = 0, is violated over many ion inertia lengths in the outflow direction. Thus, pressure terms and, to a lesser extent, inertia terms in the Generalized Ohm's Law are important in producing electron physics on ion scales. Parallel electric fields that are necessary but not sufficient for reconnection are found in the simulation and in space on ion scales in the outflow direction. They account for ∼ 10% of j · E, averaged over the current sheet. The electron exhaust jet exists over a shorter length for asymmetric reconnection than it does for symmetric reconnection. Copyright 2009 by the American Geophysical Union.