Electron acceleration at the Io’s ionosphere and origin of active longitudes in the Jovian decametric radio emission

Abstract

A mechanism for the acceleration of electrons in the ionosphere of Io due to the motion of the satellite in the magnetic field of Jupiter and the presence of an Io ionosphere, is considered. The electron acceleration is caused by an electric field due to charge separation in Io’s ionosphere and is a result from the anisotropic conductivity of its ionosphere. This field has a component parallel to the magnetic field and its value is comparable with that of the induced field. The electron “runaway” along the magnetic field is also considered in the work. Besides, the occurrence of “active longitudes” and preferable locations of the sources of the decametric radio emission of Jupiter in the northern hemisphere are interpreted. Typical energies and fluxes of the accelerated electrons injected into the Io flux tube (IFT) are estimated. It is shown that the energy stored in the electron fluxes is sufficient to support electromagnetic emissions observed from the IFT.