Kinetic Processes Leading to Generation of Waves in Instabilities in the VLISM

Vadim Roytershteyn, Nikolai Pogorelov, Federico Fraternale, Michael Gedalin

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

In this presentation we review several kinetic processes that are expected to generate waves and turbulence at and beyond the heliospheric termination shock. One such process is the relaxation of highly anisotropic (ring-like) distributions of pickup ions (PUIs) created by charge exchange between several distinct populations of neutrals and protons. Depending on the parameters, such distributions may relax via instabilities of either Alfvenic or lower-hybrid type. The first process contributes to the turbulence levels in the outer heliosheath and plays an important role in constraining theories of so-called IBEX ribbon, a distinct enhancement of the flux of energetic neutral atoms most clearly seen around energies of 1 keV. On the other hand, the lower-hybrid waves, which may be generated by PUIs further into VLISM, have been proposed to play a role in pre-acceleration of electrons ultimately enabling generation of electron beams by shocks, and of the associated radio emissions observed by Voyagers. Interaction of PUIs with shocks may also lead to enhanced level of turbulence. For example, PUIs can be reflected from the shock, creating backstreaming populations and the associated instabilities, under a much wider range of conditions than lower-energy solar wind protons. For all of these cases, we discuss theoretical considerations in the context of existing observations and compare them with results of kinetic simulations.
Original languageEnglish
Title of host publicationAGU Fall Meeting 2021
Volume31
StatePublished - 1 Dec 2021

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