Quasilinear Model of Jovian Whistler Mode Emission

This is the supporting data set for the paper by the same title published in AGU JGR Space Physics, 10.1029/2021JA029930

Key Points:

• Quasilinear model of whistler instability excited by the loss-cone electron distribution is formulated.
• The theoretical result compares reasonably well against Juno observation.
• This shows that the quasilinear theory is a useful tool for interpreting Jovian plasma wave emissions and radiations.

Abstract

The whistler mode chorus emissions are pervasively detected by the Juno satellite in Jupiter’s magnetospheric environment. The present paper pays particular attention to a sample observation made by the Juno on November 3, 2019, where typical whistler mode chorus waves are measured. The emission is characterized by a broad range of wave frequencies from below f_ce /2, where f_ce denotes the local electron cyclotron frequency,down to the lower-hybrid frequency, with a gradually downshifting frequency over time. The excitation appears to coincide with the detection of a “butterfly” pitch-angle distribution and the expected loss-cone feature associated with the energetic electrons. These anisotropic features, especially the butterfly pitch-angle distribution, gradually disappear as the waves are excited and the electron phase space distribution becomes isotropic. The present paper models these characteristics by means of quasilinear kinetic theory of the whistler instability driven by a loss-cone electron distribution function with a narrow loss-cone angle, which is to be expected from low-latitude regions of the Jovian magnetosphere. It is shown that the theoretically constructed dynamic wave spectrum is consistent with the observation made on Nov. 3, 2019. The present finding demonstrates that the quasilinear theory can be a powerful theoretical tool for interpreting various Jovian plasma wave emissions, which includes the whistler waves, but also other wave modes.