Formation of Accretion Disks in Close-Binary Systems with Magnetic Fields

TL;DR

This paper presents a 3D numerical model to simulate plasma flows in close binary systems with magnetized accretors, exploring conditions for accretion disk formation and flow types in systems with strong magnetic fields.

Contribution

It introduces a novel 3D numerical simulation approach incorporating magnetic field diffusion, buoyancy, and turbulence to study plasma flows in magnetized binary systems.

Findings

Conditions for accretion disk formation are identified.

Distinction criteria between flow types in intermediate polars and polars are discussed.

Simulations cover magnetic fields from 10^5 to 10^8 G.

Abstract

We have developed a three-dimensional numerical model and applied it to simulate plasma flows in semi-detached binary systems whose accretor possesses a strong intrinsic magnetic field. The model is based on the assumption that the plasma dynamics are determined by the slow mean flow, which forms a backdrop for the rapid propagation of MHD waves. The equations describing the slow motion of matter were obtained by averaging over rapidly propagating pulsations. The numerical model includes the diffusion of magnetic field by current dissipation in turbulent vortices, magnetic buoyancy, and wave MHD turbulence. A modified three-dimensional, parallel, numerical code was used to simulate the flow structure in close binary systems with various accretor magnetic fields, from $10^5$ to $10^8$ G. The conditions for the formation of the accretion disk and the criteria distinguishing the two types of flow corresponding to intermediate polars and polars are discussed.