How common are magnetic disconnection events in the solar wind?

Suprathermal electrons (E>80eV) in the solar wind carry heat flux away from the Sun. They are typically focussed in a narrow beam called the strahl, streaming away from the Sun along magnetic field lines. The width of the strahl is variable and at times it almost vanishes and there is greatly reduced heat flux. These events, called `heat flux dropouts' have been variously interpreted as due to disconnected magnetic flux in the heliosphere or increased pitch angle scattering or both. Establishing the amount of disconnected magnetic flux in the heliosphere is important for distinguishing between models of solar magnetic flux transport and the solar cycle reversal of the heliospheric magnetic field. Using four years of data from the Wind spacecraft, we perform a comprehensive survey of heat flux dropout events and establish an upper bound for the fraction which might be due to disconnection.