Acceleration of electric current-carrying string loop near a Schwarzschild black hole immersed in an asymptotically uniform magnetic field

TL;DR

This paper investigates how electric current-carrying string loops near a Schwarzschild black hole in a magnetic field can be accelerated to relativistic speeds, potentially explaining jet phenomena in astrophysics.

Contribution

It demonstrates that magnetic fields enhance the transmutation effect, enabling string loops to reach near-light velocities, a novel insight into jet acceleration mechanisms.

Findings

Magnetic fields increase the efficiency of string loop acceleration.

String loops can achieve velocities close to the speed of light.

The transmutation effect may explain relativistic jets in astrophysical objects.

Abstract

We study the acceleration of an electric current-carrying and axially-symmetric string loop initially oscillating in the vicinity of a Schwarzschild black hole embedded in an external asymptotically uniform magnetic field. The plane of the string loop is orthogonal to the magnetic field lines and the acceleration of the string loop occurs due to the transmutation effect turning in the deep gravitational field the internal energy of the oscillating strings to the energy of their translational motion along the axis given by the symmetry of the black hole spacetime and the magnetic field. We restrict our attention to the motion of string loop with energy high enough, when it can overcome the gravitational attraction and escape to infinity. We demonstrate that for the current-carrying string loop the transmutation effect is enhanced by the contribution of the interaction between the electric current of the string loop and the external magnetic field and we give conditions that have to be fulfilled for an efficient acceleration. The Schwarzschild black hole combined with the strong external magnetic field can accelerate the current-carrying string loop up to the velocities close to the speed of light $v \sim c$. Therefore, the string loop transmutation effect can potentially well serve as an explanation for acceleration of highly relativistic jets observed in microquasars and active galactic nuclei.