Oscillations of electric current-carrying string loop near a Schwarzschild black hole immersed in an asymptotically uniform magnetic field
We study oscillations of an electric current-carrying and axially-symmetric string loop in the vicinity of a Schwarzschild black hole embedded in an asymptotically uniform magnetic field. The radial profiles of frequencies of small oscillations of the string loop around stable equilibrium points are given for the radial and vertical harmonic modes that are relevant also in the quasi-periodic stages of the oscillations. Their properties in dependence on the uniform magnetic field intensity and angular momentum parameters of the string loops are determined. We examine the relevance of resonant phenomena of the radial and vertical string-loop oscillations at their frequency ratio 3:2. The oscillatory frequencies of the string loops are compared with the frequencies of high-frequency quasi-periodic oscillations (HF QPOs) observed in the microquasars GRS 1915+105, XTE 1550-564, GRO 1655-40 containing a black hole. We have demonstrated that the influence of the uniform magnetic field does not allow us to explain all the observed data for non-rotating black holes. Clearly, rotation of the black hole is necessary to explain the all the observed frequencies in the microquasars by the string loop oscillations.
Proceedings of RAGtime 14-16: Workshops on black holes and neutron stars
- Pub Date:
- December 2014
- string loop oscillations;
- X-ray variability;
- HF QPO observations