Electron Energy Partition across Interplanetary Shocks. I. Methodology and Data Product
Abstract
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 fieldaligned beam/strahl component. The best results were found by modeling the core as either a bikappa or a symmetric (or asymmetric) biselfsimilar VDF, while both the halo and beam/strahl components were best fit to bikappa VDF. This is the first statistical study to show that the core electron distribution is better fit to a selfsimilar VDF than a biMaxwellian under all conditions. The selfsimilar 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 } ∼ 5.4010.2 for the core, κ _{ eh } ∼ 3.585.34 for the halo, and κ _{ eb } ∼ 3.405.16 for the beam/strahl. The lowertoupper quartile range of symmetric biselfsimilar core exponents is s _{ ec } ∼ 2.002.04, and those of asymmetric biselfsimilar core exponents are p _{ ec } ∼ 2.204.00 for the parallel exponent and q _{ ec } ∼ 2.002.46 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 threepart study.
 Publication:

The Astrophysical Journal Supplement Series
 Pub Date:
 July 2019
 DOI:
 10.3847/15384365/ab22bd
 arXiv:
 arXiv:1902.01476
 Bibcode:
 2019ApJS..243....8W
 Keywords:

 methods: numerical;
 methods: statistical;
 plasmas;
 shock waves;
 solar wind;
 Sun: coronal mass ejections: CMEs;
 Physics  Space Physics;
 Astrophysics  Solar and Stellar Astrophysics;
 Physics  Plasma Physics
 EPrint:
 35 pages, 10 figures, 3 tables, under review in Astrophys. J. Suppl [updated in response to 2nd round of referee comments]