MHD accretion-ejection: jets launched by a non-isotropic accretion disk dynamo. II. A dynamo tensor defined by the disk Coriolis number

TL;DR

This paper models the disk dynamo in accretion disks using a tensor based on the Coriolis number, showing how anisotropic dynamo effects influence jet launching and stability in astrophysical systems.

Contribution

It introduces a dynamo tensor derived from mean-field dynamo theory, dependent on the Coriolis number, to improve understanding of magnetic field generation in accretion disks.

Findings

The anisotropic dynamo tensor affects jet properties.

The model stabilizes seed fields with vertical components.

Correlations link dynamo coefficients to jet dynamics.

Abstract

Astrophysical jets are launched from strongly magnetized systems that host an accretion disk surrounding a central object. Here we address the question how to generate the accretion disk magnetization and field structure required for jet launching. We continue our work from Paper I (Mattia & Fendt 2020a), considering a non-scalar accretion disk mean-field $\alpha^2\Omega$-dynamo in the context of large scale disk-jet simulations. We now investigate a disk dynamo that follows analytical solutions of mean-field dynamo theory, essentially based only on a single parameter, the Coriolis number. We thereby confirm the anisotropy of the dynamo tensor acting in accretion disks, allowing to relate both the resistivity and mean-field dynamo to the disk turbulence. Our new model recovers previous simulations applying a purely radial initial field, while allowing for a more stable evolution for seed fields with a vertical component. We also present correlations between the strength of the disk dynamo coefficients and the dynamical parameters of the jet that is launched, and discuss their implication for observed jet quantities.