Electron resonant interaction with whistler-mode waves around the Earth's bow shock I: the probabilistic approach

TL;DR

This paper introduces a probabilistic, nonlinear approach to model electron interactions with intense whistler-mode waves near Earth's bow shock, accounting for wave-packet structure and background gradients, advancing understanding of electron acceleration processes.

Contribution

It develops the first probabilistic framework for wave-particle interactions that includes nonlinear resonance and wave-packet effects in the Earth's bow shock environment.

Findings

Wave-packet size influences electron nonlinear resonance.

The approach enables evaluation of electron distribution dynamics.

Foundation for modeling complex wave-packet systems in space plasmas.

Abstract

Adiabatic heating of solar wind electrons at the Earth's bow shock and its foreshock region produces transversely anisotropic hot electrons that, in turn, generate intense high-frequency whistler-mode waves. These waves are often detected by spacecraft as narrow-band, electromagnetic emissions in the frequency range of [0.1,0.5] of the local electron gyrofrequency. Resonant interactions between these waves and electrons may cause electron acceleration and pitch-angle scattering, which can be important for creating the electron population that seeds shock drift acceleration. The high intensity and coherence of the observed whistler-mode waves prohibit the use of quasi-linear theory to describe their interaction with electrons. In this paper, we aim to develop a new theoretical approach to describe this interaction, that incorporates nonlinear resonant interactions, gradients of the background density and magnetic field, and the fine structure of the waveforms that usually consist of short, intense wave-packet trains. This is the first of two accompanying papers. It outlines a probabilistic approach to describe the wave-particle interaction. We demonstrate how the wave-packet size affects electron nonlinear resonance at the bow shock and foreshock regions, and how to evaluate electron distribution dynamics in such a system that is frequented by short, intense whistler-mode wave-packets. In the second paper, this probabilistic approach is merged with a mapping technique, which allows us to model systems containing short and long wave-packets.