A1 Refereed original research article in a scientific journal
Non-locality of Earth's quasi-parallel bow shock: injection of thermal protons in a hybrid-Vlasov simulation
Authors: Markus Battarbee, Urs Ganse, Yann Pfau-Kempf, Lucile Turc, Thiago Brito, Maxime Grandin, Tuomas Koskela, Minna Palmroth
Publisher: COPERNICUS GESELLSCHAFT MBH
Publication year: 2020
Journal: Annales Geophysicae
Journal name in source: ANNALES GEOPHYSICAE
Journal acronym: ANN GEOPHYS-GERMANY
Volume: 38
Issue: 3
First page : 625
Last page: 643
Number of pages: 19
ISSN: 0992-7689
eISSN: 1432-0576
DOI: https://doi.org/10.5194/angeo-38-625-2020
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/48697457
We study the interaction of solar wind protons with Earth's quasi-parallel bow shock using a hybrid-Vlasov simulation. We employ the global hybrid model Vlasiator to include effects due to bow shock curvature, tenuous upstream populations, and foreshock waves. We investigate the uncertainty of the position of the quasi-parallel bow shock as a function of several plasma properties and find that regions of non-locality or uncertainty of the shock position form and propagate away from the shock nose. Our results support the notion of upstream structures causing the patchwork reconstruction of the quasi-parallel shock front in a non-uniform manner. We propose a novel method for spacecraft data to be used to analyse this quasi-parallel reformation.We combine our hybrid-Vlasov results with test-particle studies and show that proton energization, which is required for injection, takes place throughout a larger shock transition zone. The energization of particles is found regardless of the instantaneous non-locality of the shock front, in agreement with it taking place over a larger region. Distortion of magnetic fields in front of and at the shock is shown to have a significant effect on proton injection.We additionally show that the density of suprathermal reflected particles upstream of the shock may not be a useful metric for the probability of injection at the shock, as foreshock dynamics and particle trapping appear to have a significant effect on energetic-particle accumulation at a given position in space. Our results have implications for statistical and spacecraft studies of the shock injection problem.
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