Collisionless kinetic regimes for quasi-stationary axisymmetric accretion disc plasmas

TL;DR

This paper develops a kinetic framework for collisionless, quasi-stationary axisymmetric accretion disc plasmas, classifying regimes based on energy and magnetic field strength, and deriving Maxwellian-like solutions for the distribution functions.

Contribution

It introduces a novel classification of collisionless plasma regimes in accretion discs and provides analytical solutions incorporating finite Larmor radius effects.

Findings

Classified plasma regimes based on energy and magnetic field criteria

Derived Maxwellian-like distribution functions for each regime

Established conditions for the validity of kinetic descriptions

Abstract

This paper is concerned with the kinetic treatment of quasi-stationary axisymmetric collisionless accretion disc plasmas. The conditions of validity of the kinetic description for non-relativistic magnetized and gravitationally-bound plasmas of this type are discussed. A classification of the possible collisionless plasma regimes which can arise in these systems is proposed, which can apply to accretion discs around both stellar-mass compact objects and galactic-center black holes. Two different classifications are determined, which are referred to respectively as energy-based and magnetic field-based classifications. Different regimes are pointed out for each plasma species, depending both on the relative magnitudes of kinetic and potential energies and the magnitude of the magnetic field. It is shown that in all cases, there can be quasi-stationary Maxwellian-like solutions of the Vlasov equation. The perturbative approach outlined here permits unique analytical determination of the functional form for the distribution function consistent, in each kinetic regime, with the explicit inclusion of finite Larmor radius-diamagnetic and/or energy-correction effects.