On the formation of Io-induced acceleration regions related to Jovian aurora

By means of 3D resistive MHD simulations we present an effective mechanism to accelerate charged particles which may contribute to the Jovian auroral luminosity. We restrict ourselves to the Io-induced part, the so-called Io footprint. We apply the present knowledge about the terrestrial aurora to Jupiter and perform in a first step global simulations of the Jovian magnetosphere in order to investigate the generation of a field-aligned current system by Io with particular stress on the influence of mass loading effects. The MHD modes excited by this interaction transport the velocity shear and magnetic perturbations into the Jovian ionosphere, thereby establishing a current system similar to the Birkeland currents in the Earthʹs magnetosphere-ionosphere system. In a second step we perform local simulations of the Jovian magnetosphere-ionosphere system. In the considered latitudes in consequence of the velocity shear the current density is expected to rise up to supercritical values exciting microinstabilities which lead to anomalous resistivity. This resistivity gives rise to macroscopic resistive instabilities which in their nonlinear evolution result in considerably enhanced parallel electric fields. Thus, a field-aligned potential can be built up in these resistive regions accelerating charged particles to energies of several keV.