Direct evidence of nonstationary collisionless shocks in space plasmas

Collisionless shocks are ubiquitous throughout the universe: around stars, supernova remnants, active galactic nuclei, binary systems, comets, and planets. Key information is carried by electromagnetic emissions from particles accelerated by high Mach number collisionless shocks. These shocks are in...

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Bibliographic Details
Published in:Science advances 2019-02, Vol.5 (2), p.eaau9926-eaau9926
Main Authors: Dimmock, Andrew P, Russell, Christopher T, Sagdeev, Roald Z, Krasnoselskikh, Vladimir, Walker, Simon N, Carr, Christopher, Dandouras, Iannis, Escoubet, C Philippe, Ganushkina, Natalia, Gedalin, Michael, Khotyaintsev, Yuri V, Aryan, Homayon, Pulkkinen, Tuija I, Balikhin, Michael A
Format: Article
Language:English
Subjects:
Physics
SciAdv r-articles
Sciences of the Universe
Space Sciences
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Summary:Collisionless shocks are ubiquitous throughout the universe: around stars, supernova remnants, active galactic nuclei, binary systems, comets, and planets. Key information is carried by electromagnetic emissions from particles accelerated by high Mach number collisionless shocks. These shocks are intrinsically nonstationary, and the characteristic physical scales responsible for particle acceleration remain unknown. Quantifying these scales is crucial, as it affects the fundamental process of redistributing upstream plasma kinetic energy into other degrees of freedom-particularly electron thermalization. Direct in situ measurements of nonstationary shock dynamics have not been reported. Thus, the model that best describes this process has remained unknown. Here, we present direct evidence demonstrating that the transition to nonstationarity is associated with electron-scale field structures inside the shock ramp.
ISSN:2375-2548
2375-2548
DOI:10.1126/sciadv.aau9926