MMS Observations of the Flux Transfer Events in presence of the cold ions

Flux Transfer Events (FTE) generally are the reconnected magnetic flux tubes moving away from the reconnection site and commonly observed when the BZ component of the solar wind magnetic field is negative, which provides an active magnetic reconnection at the subsolar magnetopause. As a direct signature of the reconnection, the FTEs are subjects of great interests to the Magnetospheric Multiscale mission (MMS). MMS consists of the four spacecraft equipped with identical scientific payload. We use Fast Plasma Investigation (FPI) and magnetic field data to study set of the FTEs observed by the MMS tetrahedron on October 10, 2015. The MMS orbit is configured such that apogee is at the magnetopause, the events of interest are just inside ( 1 Re) the magnetopause and both sheath and magnetospheric plasmas are detected. MMS detected cold ions under nominal solar wind conditions. The observations are characterized by the presence of the cold ions on both sides of the events, which are seen as dispersive ion signatures from low (few eV) to higher energies at the leading edge and from high to low at the trailing edge of the FTEs. In this paper we study an origin and dynamic of cold ions embedded to the FTEs. The event was captured in the burst mode, which gives the opportunity to study the event with unprecedented time and spatial resolution.