Electron Energy Partition across Interplanetary Shocks. I. Methodology and Data Product
Analyses of 15,314 electron velocity distribution functions (VDFs) within ±2 hr of 52 interplanetary (IP) shocks observed by the Wind spacecraft near 1 au are introduced. The electron VDFs are fit to the sum of three model functions for the cold dense core, hot tenuous halo, and field...
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| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2019-01-01
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| Series: | The Astrophysical Journal Supplement Series |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4365/ab22bd |
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| Summary: | Analyses of 15,314 electron velocity distribution functions (VDFs) within ±2 hr
of 52 interplanetary (IP) shocks observed by the Wind spacecraft near 1 au are introduced. The electron VDFs are fit to the sum of
three model functions for the cold dense core, hot tenuous halo, and
field-aligned beam/strahl component. The best results were found by modeling the
core as either a bi-kappa or a symmetric (or asymmetric) bi-self-similar VDF,
while both the halo and beam/strahl components were best fit to bi-kappa VDF.
This is the first statistical study to show that the core electron distribution
is better fit to a self-similar VDF than a bi-Maxwellian under all conditions.
The self-similar distribution deviation from a Maxwellian is a measure of
inelasticity in particle scattering from waves and/or turbulence. The ranges of
values defined by the lower and upper quartiles for the kappa exponents are κ _ec ∼ 5.40–10.2 for the core, κ _eh ∼ 3.58–5.34 for the halo,
and κ _eb ∼ 3.40–5.16 for the
beam/strahl. The lower-to-upper quartile range of symmetric bi-self-similar core
exponents is s _ec ∼ 2.00–2.04, and
those of asymmetric bi-self-similar core exponents are p _ec ∼ 2.20–4.00 for the
parallel exponent and q _ec ∼ 2.00–2.46 for the
perpendicular exponent. The nuanced details of the fit procedure and description
of resulting data product are also presented. The statistics and detailed
analysis of the results are presented in Paper II and Paper III of this
three-part study. |
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| ISSN: | 0067-0049 |