Theoretical interpretation of Jupiter's multibanded whistler mode emission

Abstract

Three distinct bands of whistler mode emissions were detected by the Voyager 1 and Voyager 2 plasma wave instruments during the encounter with Jupiter. The broadband whistler mode hiss below 1 kHz and two narrowbanded, high‐frequency emissions near 10 kHz were identified as whistler mode chorus and half electron cyclotron emission. In the present analysis the entire electron velocity space distribution is modeled by a superposition of three anisotropic components, two kappa distributions of different spectral index, and a drifting Maxwellian distribution. Applying a linear instability analysis on this specific distribution and providing the basic plasma parameters from spacecraft observations yields a highly accurate picture of the structure of the observed discrete Jovian whistler emission spectrum. It is concluded that the generation of the hiss structure can be interpreted to be a consequence of resonating suprathermal non‐Maxwellian electrons, whereas the chorus is generated by a nearly bi‐Maxwellian population. The half electron cyclotron emission can be associated with the interaction of a drifting, anisotropic component of keV electrons. The analysis of the main emission bands of a specific full spectrum can serve as representative pattern for the interpretation of various whistler mode events in planetary magnetospheres.