Persistence of Ion Cyclotron Waves and Stochasticity of Kinetic Alfvén Waves in the Solar Wind

Abstract

This paper investigates the nature of the physical processes underlying the origin of the Ion Cyclotron Waves (ICWs) and Kinetic Alfvén Waves (KAWs) in the solar wind, by studying their Waiting Time Distributions (WTDs). The results show that ICWs and KAWs do not share common statistical properties: while KAWs independently occur as stochastic, uncorrelated wave packets governed by Poisson statistics, ICWs are highly correlated, thus departing from the Poisson hypothesis. The results based on the WTD analysis may cast more light on the mechanisms actively at work in the generation of the two wave modes. Specifically, while the stochastic character of KAWs may be reminiscent of the random convection-driven jostling of the flux-tube foot-points that generates the Alfvén waves in the lower solar atmosphere, the correlations among the ICW events can be effectively explained on the basis of the persistent nature of the mechanism underlying the local origin of ICWs, namely the proton cyclotron instability. Alternative explanations for the observed distribution of ICW waiting times, based on a piecewise-constant Poisson process involving time-varying rates, are also reported.

Observation of Alfvén Ion Cyclotron Waves in ICME Magnetic Clouds at 1 au

“…The θ VB is consistently found near 40 • (refer Figure 3) during the MC interval. The observations of the coexistence of Alfvénic mode with ICWs may support the lefthanded polarized (negative) quasi-parallel flow of the AIC wave (He et al 2011a;Telloni 2020). Further, we found hightemperature anisotropy T p⊥ /T p∥ during the passage of ICME MC.…”

“…Moreover, we observed θ VB < 40°, which implies the parallel propagation of AIC waves. We restricted ourselves as this wave is quasi-parallel in nature (He et al 2011a;Telloni 2020) though many simulations and observation studies in the literature defined this wave as oblique in nature (Lacombe & Belmont 1995;Harmon & Coles 2005;He et al 2011b;Isenberg & Vasquez 2011;Maneva et al 2015).…”

“…Further, we have used fast Fourier transform to determine the total magnetic field power spectral density (PSD) and normalized magnetic helicity (σ m ) for each identified ICME MC event (see Section 2.1). To explain the existence of significant waveparticle interaction, we applied criteria σ m |0.5| as suggested in Telloni (2020). A total of 14 ICME flux rope events out of 401 events listed in the catalog satisfied the above criteria.…”

“…It is zero for plane-polarized waves and ±1 for right-and left-handed circularly polarized waves. Moreover, the direction of the background magnetic field strongly influences the sign of the normalized magnetic helicity (Telloni et al 2012(Telloni et al , 2013(Telloni et al , 2019Telloni 2020). The high speed of the solar wind (> > V A ) means that as the magnetic field rotates, the Doppler shift of the wave traveling over the spacecraft may change the sign of the measured helicity.…”

Long-Term Science Goals with In Situ Observations at the Sun-Earth Lagrange Point L4

“…The impact of kinetic-scale waves on solar wind particles is notable not only due to their intensive and brief interactions, as elucidated by linear/nonlinear processes (Bowen et al 2022) but also due to their extended lifespan (Telloni 2021). While most of these waves, induced by kinetic instabilities, are believed to originate in the inner heliosphere (Jian et al 2009;Jagarlamudi et al 2021;Liu et al 2023), observations of the solar wind near Earth consistently reveal the presence of these waves at 1 AU.…”