Whistler and Broadband Electrostatic Waves in the Multiple X-line
Reconnection at the Magnetopause
Abstract
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.