Fast radio imaging of Jupiterʹs magnetosphere at low-frequencies with LOFAR

Jupiter emits intense decameter (DAM) radio waves, detectable from the ground in the range ∼ 10–40 MHz. They are produced by energetic electron precipitations in its auroral regions (auroral-DAM), as well as near the magnetic footprints of the Galilean satellite Io (Io-DAM). Radio imaging of these decameter emissions with arcsecond angular resolution and millisecond time resolution should provide:(1) roved mapping of the surface planetary magnetic field, via imaging of instantaneous cyclotron sources of highest frequency; ements of the beaming angle of the radiation relative to the local magnetic field, as a function of frequency; ed information on the Io–Jupiter electrodynamic interaction, in particular the lead angle between the Io flux tube and the radio emitting field line; information on the origin of the sporadic drifting decameter S-bursts, thought to be electron bunches propagating along magnetic field lines, and possibly revealing electric potential drops along these field lines; observation of DAM emission possibly related to the Ganymede–Jupiter, Europa–Jupiter and/or Callisto–Jupiter interactions, and their energetics; ation on the magnetospheric dynamics, via correlation of radio images with ultraviolet and infrared images of the aurora as well as of the Galilean satellite footprints, and study of their temporal variations; roved mapping of the Jovian plasma environment (especially the Io torus) via the propagation effects that it induces on the radio waves propagating through it (Faraday rotation, diffraction fringes, etc.); ly on the long-term a better accuracy on the determination of Jupiterʹs rotation period. maging should be permitted by the very high intensity of Jovian decameter bursts. LOFARʹs capability to measure the full polarization of the incoming waves will be exploited. The main limitation will come from the maximum angular resolution reachable. We discuss several approaches for bringing it close to the value of ∼ 1 ″ at 30–40 MHz, as required for the above studies.