Quasilinear Model of Jovian Whistler Mode Emission. Issue 12 (5th December 2021)

• Record Type: Journal Article
• Authors: Yoon, P. H.; Menietti, J. D.; Kurth, W. S.; Allegrini, F.; Bolton, S. J.
• Is Part Of: Journal of geophysical research. Volume 126:Issue 12(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-05
• Subjects: Juno mission -- Jovian magnetosphere -- whistler chorus waves -- quasilinear -- electron loss‐cone -- instability; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2021JA029930
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: The whistler mode chorus emissions are pervasively detected by the Juno satellite in Jupiter's magnetospheric environment. This article pays particular attention to a sample observation made by the Juno on 3 November 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 aim of this article is to model the 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 3 November 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. Plain Language Summary: NASA's Juno space probe orbiting the planet Jupiter since 2016, has detected the whistler waves. It is the same type of very low frequency electromagnetic waves generated by lightning in the Earth's atmosphere, which can be converted to whistling audio wave using a suitable receiver. This article puts forth a plasma physics based explanation of the Juno whistler wave observation. According to this theory, the spiraling motion of energetic electrons trapped in Jupiter's magnetic dipole field collectively amplify the very low frequency electromagnetic noise‐like signals in a manner analogous to the process taking place in the Earth's upper atmosphere. 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