Whistler and Broadband Electrostatic Waves in the Multiple X-Line Reconnection at the Magnetopause

We investigate whistler-mode waves and broadband electrostatic waves (EWs) within an ion diffusion region (IDR) at the magnetopause. The quasi-parallel whistlers are observed in the separatrix regions associated with the electron anisotropy or loss cone, while the oblique whistlers, the Buneman-type waves, and the oblique EWs are observed in the center of the current sheet associated with the accelerated electron or ion beams. The whistlers are linked with Buneman-type waves by the electron Pacman distribution rather than the wave-wave process. The accelerated cold electron beams excite the Buneman-type instabilities and make the anisotropy or loss cone of hot electrons less apparent, which led to the conversion of the whistlers from quasi-parallel to oblique. Additionally, the oblique EWs are associated with the ion beams produced by the multiple X-line reconnection. These results provide a further understanding of the relation between plasma waves and plasma kinetics in the IDR.