Wave Activity in a Reconnection Current Sheet near an X-Line on the Dayside Magnetopause

During an event on December 4, 2017, MMS spent nearly two minutes crossing from the magnetosphere into the magnetosheath. While crossing, MMS encountered numerous magnetic field reversals, x-lines, and flux ropes. In the event discussed here, MMS2 passed through an x-line and saw crescent-shaped electron distributions which are usually associated with magnetic reconnection. The electron crescents periodically disappeared and reappeared as the N-component of the electric field also disappeared and reappeared at a frequency on the order of a few Hertz. The electrons appear to be frozen-in to the magnetic field at this time while the ions do not, and so this event is reminiscent of a lower-hybrid drift wave. Such waves usually are found on the sphere-side of the x-line near the stagnation point, but in this case the waves only appear near the x-line and are not associated with any oscillations in the magnetic field.