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

Abstract:

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.