Coupling of Landau and anomalous/cyclotron resonances for oblique whistler waves

Determine whether Landau resonance and anomalous/cyclotron resonances are coupled for obliquely propagating whistler-mode waves in magnetized plasmas, and, if coupling exists, characterize the nature of this coupling.

Background

Wave–particle interactions in magnetized plasmas include Landau resonance (n=0) and cyclotron resonance (n=1), with anomalous resonance arising when strong wave fields significantly perturb particle gyromotion. For oblique whistler-mode waves, prior work suggested the possibility of simultaneous Landau and anomalous/cyclotron resonances. However, the existence and mechanism of coupling between these resonances had not been clearly established.

This paper investigates oblique whistler waves and proton interactions using MMS observations and simulations, aiming to identify simultaneous Landau and anomalous resonances and examine potential coupling. The explicit uncertainty raised in the Introduction motivates determining whether such coupling occurs and, if so, describing how it operates.

References

Interestingly, the Landau and anomalous/cyclotron resonances may occur simultaneously for oblique-propagating waves, although it remains unclear whether or how they are coupled.

— Identification of coupled Landau and anomalous resonances in space plasmas (2405.16065 - Li et al., 25 May 2024) in Section 1. Introduction