Magnetized 1.5-dimensional advective accretion flows around black holes

TL;DR

This paper investigates how large-scale magnetic fields influence angular momentum transport and magnetic barrier formation in 1.5-dimensional advective accretion flows around black holes, potentially explaining episodic jet formation.

Contribution

It introduces a model of magnetized accretion flows that accounts for magnetic barriers and their role in jet formation, highlighting the impact of magnetic field geometry.

Findings

Magnetic barriers can halt or redirect accreting matter near black holes.

Strong poloidal and toroidal magnetic fields influence flow dynamics and jet formation.

Magnetically dominated flows show distinct rotational and deceleration profiles.

Abstract

We address the role of large scale magnetic stress in the angular momentum transport, as well as the formation of different kinds of magnetic barrier in geometrically thick, optically thin, vertically averaged 1.5-dimensional advective accretion flows around black holes. The externally generated magnetic fields are captured by the accretion process from the environment, say, companion stars or interstellar medium. This field becomes dynamically dominant near the event horizon of a black hole due to continuous advection of the magnetic flux. In such magnetically dominated accretion flows, the accreting matter either decelerates or faces magnetic barrier in vicinity of the black hole depending on the magnetic field geometry. We find that the accumulated strong poloidal fields along with certain toroidal field geometry help in the formation of magnetic barrier which may knock the matter to infinity. When matter is trying to go back to infinity after getting knocked out by the barrier, in some cases it is prevented being escaped due to cumulative action of strong magnetic tension and gravity, and hence another magnetic barrier. We suggest, this kind of flow may be responsible for the formation of episodic jets in which magnetic field can lock the matter in between these two barriers. We also find that for the toroidally dominated disc, the accreting matter rotates very fast and decelerates towards the central black hole.