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JGR Space Physics - 2022 - Artemyev - On the Role of Whistler‐Mode Waves in Electron Interaction With Dipolarizing Flux.pdf (7.84 MB)

On the role of whistler-mode waves in electron interaction with dipolarizing flux bundles

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posted on 2022-05-18, 14:47 authored by Anton Artemyev, Anatoly NeishtadtAnatoly Neishtadt, Vassillis Angelopoulos

The magnetotail is the main source of energetic electrons for Earth’s inner magnetosphere. Electrons are adiabatically heated during flow bursts (rapid earthward motion of the plasma) within dipolarizing flux bundles (concurrent increases and dipolarizations of the magnetic field). The electron heating is evidenced near or within dipolarizing flux bundles as rapid increases in the energetic electron flux (10–100 keV); it is often referred to as injection. The anisotropy in the injected electron distributions, which is often perpendicular to the magnetic field, generates whistler-mode waves, also commonly observed around such dipolarizing flux bundles. Test-particle simulations reproduce several features of injections and electron adiabatic dynamics. However, the feedback of the waves on the electron distributions has been not incorporated into such simulations. This is because it has been unclear, thus far, whether incorporating such feedback is necessary to explain the evolution of the electron pitch-angle and energy distributions from their origin, reconnection ejecta in the mid-tail region, to their final destination, and the electron injection sites in the inner magnetosphere. Using an analytical model we demonstrate that wave feedback is indeed important for the evolution of electron distributions. Combining canonical guiding center theory and the mapping technique we model electron adiabatic heating and scattering by whistler-mode waves around a dipolarizing flux bundle. Comparison with spacecraft observations allows us to validate the efficacy of the proposed methodology. Specifically, we demonstrate that electron resonant interactions with whistler-mode waves can indeed change markedly the pitch-angle distribution of energetic electrons at the injection site and are thus critical to incorporate in order to explain the observations. We discuss the importance of such resonant interactions for injection physics and for magnetosphere-ionosphere coupling.

Funding

National Aeronautics and Space Administration (NASA). Grant Numbers: 80NSSC20K1578, 80NSSC19K0266, 80NSSC21K0729, NNX14AN68G

NSF, BFA, Budget Division (BD). Grant Numbers: AGS-1242918, AGS-2019950

Leverhulme Trust. Grant Number: RPG-2018-143

History

School

  • Science

Department

  • Mathematical Sciences

Published in

Journal of Geophysical Research: Space Physics

Volume

127

Issue

4

Publisher

American Geophysical Union

Version

  • VoR (Version of Record)

Rights holder

© American Geophysical Union

Publisher statement

This paper was published in the journal Journal of Geophysical Research: Space Physics and is available at https://doi.org/10.1029/2022JA030265

Acceptance date

2022-03-19

Publication date

2022-04-05

Copyright date

2022

ISSN

2169-9380

eISSN

2169-9402

Language

  • en

Depositor

Prof Anatoly Neishtadt. Deposit date: 17 May 2022

Article number

e2022JA030265

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