Three Dimensional Simulations of Advective, Sub-Keplerian Accretion Flow onto Non-rotating Black Holes

TL;DR

This study uses three-dimensional hydrodynamic simulations to examine the stability of sub-Keplerian accretion disks around non-rotating black holes, revealing stability under symmetric conditions but susceptibility to non-axisymmetric perturbations.

Contribution

First 3D simulations of sub-Keplerian accretion flows onto black holes, analyzing stability and effects of non-axisymmetric perturbations.

Findings

Disks remain stable and axisymmetric without perturbations.

Non-axisymmetric perturbations induce disk instability.

Stable disk structure persists close to the black hole.

Abstract

We study the time evolution of sub-Keplerian transonic accretion flow onto a non-rotating black hole using a three-dimensional, inviscid hydrodynamics simulation code. Prior two-dimensional simulations show that centrifugal barrier in the accreting matter may temporarily halt the nearly free-falling matter and produce a stable, geometrically thick disk which may contain turbulent eddies. Our goal in this work is to investigate whether the disk develops any instability because of this turbulence when we dynamically activate all three dimensions. We find that the disk remains stable and axisymmetric even close to the central black hole. However, if we explicitly apply non-axisymmetric azimuthal perturbation, the axisymmetric structure of the disk is destroyed and instability is developed.