# Black hole magnetosphere with small scale flux tubes--II. Stability and dynamics

## TL;DR

This study uses 3D force-free simulations to explore how small-scale magnetic flux tubes near black holes influence X-ray emission, revealing that confinement prevents jet formation and leads to localized energy dissipation.

## Contribution

It demonstrates how magnetic flux tube dynamics under confinement affect energy release and jet formation near black holes, providing insights into X-ray emission mechanisms.

## Key findings

- Flux tubes become kink unstable and dissipate energy close to the black hole.
- Strong confinement prevents jet formation despite flux tube inflation.
- Energy dissipation may heat plasma and produce X-ray emission.

## Abstract

In some Seyfert Galaxies, the hard X-rays that produce fluorescent emission lines are thought to be generated in a hot corona that is compact and located at only a few gravitational radii above the supermassive black hole. We consider the possibility that this X-ray source may be powered by small scale magnetic flux tubes attached to the accretion disk near the black hole. We use three dimensional, time dependent force-free simulations in a simplified setting to study the dynamics of such flux tubes as they get continuously twisted by the central compact star/black hole. We find that, the dynamical evolution of the flux tubes connecting the central compact object and the accretion disk is strongly influenced by the confinement of the surrounding field. Although differential rotation between the central object and the disk tends to inflate the flux tubes, strong confinement from surrounding field quenches the formation of a jet-like outflow, as the inflated flux tube becomes kink unstable and dissipates most of the extracted rotational energy relatively close to the central object. Such a process may be able to heat up the plasma and produce strong X-ray emission. We estimate the energy dissipation rate and discuss its astrophysical implications.