**Publication date:** Jun 2013

**Abstract:**

We study motion of an electric current-carrying string loop oscillating

in the vicinity of the Schwarzschild black hole immersed in an external

uniform magnetic field. The dependence of boundaries and different types

of motion of the string loop on magnetic field strength is found. The

dynamics of the string loop in the Cartesian xy plane depends both on

value and direction of the magnetic field and current. It is shown that

the magnetic field influence on the behavior of the string loop is quite

significant even for weak magnetic field strength. The oscillation of

the string loop becomes stronger or weaker in dependence on the

direction of the Lorenz force. We illustrate the various regimes of the

trajectories of the string loop that can fall down into the black hole,

escape to infinity, or be trapped in the finite region near the horizon

for the different representative values of the magnetic field. We have

also considered the flat spacetime limit as the condition of the escape

of the string loop from the neighborhood of the black hole to infinity.

We found the expression for the magnetic field strength for which the

oscillatory motion of the string loop totally vanishes and the string

loop can have maximal acceleration in the perpendicular direction to the

plane of the loop.

**Authors:**

Tursunov, Arman; Kološ, Martin; Ahmedov, Bobomurat; Stuchlík, Zdeněk;