Low-energy (<20 eV) electron velocity distribution in the Earth's magnetosheath

Determine the electron velocity distribution function below approximately 20 eV in the Earth's magnetosheath, where measurements are contaminated by photoelectrons and secondary electrons, to replace the Maxwellian assumption used in fluid-based theoretical analysis of observed solitary waves.

Background

In developing a fluid-model interpretation of the observed solitary waves, the authors assume a Maxwellian form for the electron distribution below ~20 eV to match densities, but note that the actual electron distribution at these low energies is not measured due to instrument contamination.

This uncertainty directly affects theoretical conclusions about whether fluid models could describe the solitary waves and underpins the kinetic interpretation (electron holes) advanced in the paper.