The dependence of the viscosity-parameter on the disk scale height profile

TL;DR

This paper investigates how the disk scale height affects the viscosity parameter in accretion disks, showing it remains constant under certain conditions but varies when additional processes are considered, impacting turbulence and viscosity distribution.

Contribution

It demonstrates that the disk height scale is constant under hydrostatic equilibrium and sub-sonic turbulence, and explores how additional processes alter the viscosity parameter across the disk.

Findings

Height scale is constant under specific conditions.

Additional processes cause the viscosity parameter to vary radially.

Turbulence likely contributes to disk viscosity.

Abstract

It is shown that the height scale for accretion disks is a constant whenever hydrostatic equilibrium and sub-sonic turbulence regime hold in the disk. In order to have a variable height scale, processes that do contribute with an extra term to the continuity equation are needed. This makes the viscosity parameter much greater in the outer region and much smaller in the inner region. Under these circumstances, turbulence is a presumable source of viscosity in the disk.