Abstract
The Earth’s magnetotail contains a current sheet separating the
anti-Sunward field of the southern lobe from the sunward-pointing
northern lobe. Herein, we report tail current sheets that are supported
by only electron currents. We examine one electron-only current sheet in
detail, and briefly discuss ten others. Three current sheets are
interpreted in terms of the time-evolution of reconnection onset. These
current sheets show evidence of parallel electron heating, perpendicular
ion heating, and current sheet expansion. These features are consistent
with electron and ion behavior during traditional “electron-ion”
reconnection. Ground-based and in-situ data show that electron-ion
reconnection occurs shortly after each “pre-ion reconnection”
electron-only reconnection event. This suggests that electron-only
reconnection can act as a precursor to electron-ion reconnection. We
note that five events occur shortly after a period of electron-ion
reconnection, which suggests that electron-only reconnection is more
than merely a precursor to ion reconnection.