Statistical properties of solar wind reconnection exhausts

Abstract

The solar wind provides an excellent opportunity to study the exhausts that form as a result of symmetric guide field reconnection, where spacecraft rapidly cross the exhausts far downstream of the X line. We study the statistical properties of solar wind exhausts through a superposed epoch analysis of 188 events observed at 1 AU using the Wind spacecraft. These events span a range of guide fields of 0 to 10 times the reconnecting magnetic field and inflow region plasma beta of 0.1 to 6.6. This analysis reveals that the out-of-plane magnetic field is enhanced within solar wind exhausts. Furthermore, the amount by which the plasma density and ion temperature increase from inflow region to exhaust region is found to be a function of the inflow region plasma beta and reconnection guide field, which explains the lack of these enhancements in a subset of previous observations. This dependence is consistent with the scaling of ion heating with inflow region Alfven speed, which is measured to be consistent with previous observations in the solar wind and at the magnetopause.