Understanding the generation of magnetosonic waves using PIC simulations in a dipole magnetic field

Fast magnetosonic waves (a.k.a equatorial noise; hereafter MSWs) are known to occur most strongly within about ±10° magnetic latitude in the inner magnetosphere. The proton shell/ring distribution is the primary source of these waves. It has long been understood that the source of MSWs is located near the magnetic equator and the excited MSWs remain confined to the magnetic equator because of their quasi-perpendicular propagation. A recent two-dimensional particle-in-cell (PIC) simulation in a meridional plane using large anisotropy seemed to support the suggested generation mechanism.