Origin of the differential fluxes of low-energy electrons in the inner heliosheath

Abstract

The study addresses the question of the origin of low-energy electrons measured by Voyager 1 in the multi-keV range in the inner heliosheath. It intends to demonstrate that the observed keV-fluxes of electrons are consistent with their transmission through the termination shock under the influence of the associated electrostatic field. A power-law representation of the electron velocity distribution just downstream of the solar wind termination shock is motivated and formulated in terms of a so-called κ-distribution function. From this initial function spectral electron fluxes in the range 40-70 keV are derived and compared to the data. It is shown that with κ-values between 7 and 8 the data can be satisfactorily explained. Given these comparatively high κ-values, it is concluded that the electron distribution just downstream of the termination shock relaxes toward but does not reach a Maxwellian shape in the inner heliosheath