Acceleration of string loops in the Schwarzschild-de Sitter geometry

TL;DR

This paper investigates how current-carrying string loops can be accelerated in Schwarzschild-de Sitter spacetime, potentially explaining relativistic jets in astrophysical objects through energy transmutation near black holes.

Contribution

It demonstrates that string loops can be accelerated to relativistic speeds in Schwarzschild-de Sitter spacetime, including from rest, due to gravitational and cosmic repulsion effects.

Findings

String loops can be scattered near black hole horizons.

Energy of oscillations can convert to linear motion efficiently.

Loops can reach velocities close to the speed of light, explaining relativistic jets.

Abstract

We study acceleration of current-carrying string loops governed by the presence of an outer tension barrier and an inner angular momentum barrier in the field of Schwarzschild-de Sitter black holes. We restrict attention to the axisymmetric motion of string loops with energy high enough, when the string loop can overcome the gravitational attraction and escape to infinity. We demonstrate that string loops can be scattered near the black hole horizon, and the energy of string oscillations can be efficiently converted to the energy of their linear motion. Such a transmutation effect can potentially represent acceleration of jets in active galactic nuclei and microquasars. We give the conditions limiting energy available for conversion onto the jetlike motion. Surprisingly, we are able to show that string loops starting from rest can be accelerated up to velocities v\simc even in the field of Schwarzschild black holes, if their angular momentum parameter is low enough. Such loops could serve as an explanation of highly relativistic jets observed in some quasars and active galactic nuclei. The cosmic repulsion becomes important behind the so-called static radius where it accelerates the linear motion of the string loops up to velocity v=c that is reached at the cosmic horizon of the Schwarzschild-de Sitter spacetimes independently of the angular momentum parameter of the strings.