On the Jovian Machinery: from Magnetodisk Perturbations to the Generation of Radio Emissions.

Abstract:

The Galileo observations are analyzed to establish possible relationships between dynamic processes occurring in the jovian magnetosdisk and variations in the flux of the radio emissions. More specifically, it is shown that there is a general good correlation between increases of the azimuth component of the magnetic field (B_phi) seen in the middle/distant magnetodisk (distances ranging between 20 to 80 Rj) and intensification of the auroral radio emissions. A simple explanation is that the variations of B_phi are related to modifications in the current system linking the ionosphere to the disk and, thus, to variations in the intensity of the parallel currents with implications on the associated auroral processes. An interpretation is proposed using Hill’s model of the enforcement of the magnetodisk rotation with, however, adaptations to the observations that require the use of a current sheet model (adapted from Nichols, 2003) . The link with possible variations in the radial mass transport is discussed, with estimates of the overall power associated to the magnetic torque that enforces the corotation and accelerates the bulk plasma. From an astrophysical perspective, this offers an interesting opportunity to quantify a transfer of rotational energy from to central body to a magnetosdisk and compared it to the resulting radiations (here in the radio domain).