High-latitude radiation and resonant enhancements of the Jovian synchrotron emissions

Abstract

A model describing (1) short time scale increases in Jovian synchrotron radiation and (2) emissions from high Jovian latitudes is presented. In the present model resonant interaction between oblique whistler waves and relativistic electrons diffuses the energy and the pitch angle of electrons which bounce along the Jovian magnetic field. The resonant interaction violates the first two adiabatic invariants and the energy diffusion results in hardening of the electron spectrum and in intensification of the synchrotron radiation. This model complements the radial diffusion process which (a) violates the third adiabatic invariant of a seed population via interaction with low-frequency magnetospheric oscillations and (b) increases the flux of energetic electrons at low L-shells over long time scales by conserving the first adiabatic invariant. The high-latitude emissions indicate also acceleration of bouncing electrons and radiation in the region of the strongest magnetic field. The seed particles and whistler waves determine the form of the electron distribution tail. This tail enhances the high-latitude synchrotron radiation observed at Earth. The resulting emissivities of the nonthermal radio waves in the ordinary/extraordinary modes of propagation, the polarization and the intensity spectrum observed at Earth due to these high-energy populations are calculated.