STEREO SWEA Observations of Solar Wind Halo Electron Anomalous Heat Fluxes and their Organization by Solar Wind Structure

STEREO SWEA (Solar Wind Electron Analyzer) provides the opportunity to observe solar wind halo electron heat fluxes and strahl over 4pi steradians at locations free of Earth bow shock contamination. We have analyzed these measurements together with the magnetic field and plasma parameters to determine their organization with solar wind stream structure during the period between early 2007 and late 2009. This period is characterized by a very low level of solar activity and thus presents an opportunity to diagnose the anomalous features, determining their location and character. This includes heat fluxes that appear to be traveling back toward the Sun, possibly indicating folded interplanetary field lines, interplanetary field loops which may be part of ICMEs, or sources of suprathermal electrons at shocks beyond 1 AU. Our results give a broad view of the issues related to using heat fluxes to interpret interplanetary field topology, even with the benefit of 4pi observations and two spacecraft.