Generation of the jovian radio decametric arcs from the Io Flux Tube

Abstract

Jupiter's radio emissions are dominated in intensity by decametric radio emissions due to the Io‐Jupiter interaction. Previous analyses suggest that these emissions are cyclotron‐maser emissions in the flux tubes connecting Io or Io's wake to Jupiter. The electrons that trigger the emission are thought to be accelerated toward Jupiter. We present simulations of this hot electron population under the assumption of impulsive acceleration, consistent with the accelerated electron populations seen in the Io's wake by Galileo during its flyby in 1995. After the impulsive acceleration phase, the electrons are supposed to have an adiabatic motion along the magnetic field lines. Near Jupiter, a loss cone and a shell appear in the magnetically mirrored electron population. Such features are able to amplify extraordinary (X) mode radio waves. We compute the X‐mode growth rate, which allows us to build theoretical dynamic spectra of the resulting Jovian radio emissions. The study of the growth rates obtained by simulation and their comparison with ground‐based radio observations provide strong constraints on the acceleration process and energy sources at the origin of the Io‐controlled decameter emissions.