Collisional cross sections and momentum distributions in astrophysical plasmas: dynamics and statistical mechanics link

TL;DR

This paper investigates how microscopic ion collision dynamics influence the momentum distribution in stellar plasmas, linking statistical mechanics with quantum effects and proposing new cross sections for better modeling.

Contribution

It introduces a novel cross section related to quantum effects and connects ion collision dynamics with non-extensive statistical mechanics in astrophysical plasmas.

Findings

Different cross sections cause specific corrections to Maxwellian distributions.

A new cross section linked to quantum uncertainty is proposed.

Potential connection between microscopic dynamics and non-extensive statistics.

Abstract

We show that, in stellar core plasmas, the one-body momentum distribution function is strongly dependent, at least in the high velocity regime, on the microscopic dynamics of ion elastic collisions and therefore on the effective collisional cross sections, if a random force field is present. We take into account two cross sections describing ion-dipole and ion-ion screened interactions. Furthermore we introduce a third unusual cross section, to link statistical distributions and a quantum effect originated by the energy-momentum uncertainty owing to many-body collisions, and propose a possible physical interpretation in terms of a tidal-like force. We show that each collisional cross section gives rise to a slight peculiar correction on the Maxwellian momentum distribution function in a well defined velocity interval. We also find a possible link between microscopical dynamics of ions and statistical mechanics interpreting our results in the framework of non-extensive statistical mechanics.