Dynamics of an electric current-carrying string loop near a Schwarzschild black hole embedded in an external magnetic field

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

doi:10.1103/physrevd.87.125003

Cited by 18 publications

(15 citation statements)

References 41 publications

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“…implied by the condition H = 0, given by reparameterization invariance of the action (10). We can make the rescaling E b → E b /µ and J → J/ √ µ, assuming µ > 0.…”

Section: Energy Boundary Functionmentioning

confidence: 99%

Dynamics of current-carrying string loops in the Kerr naked-singularity and black-hole spacetimes

Kološ

Stuchlík

2013

Phys. Rev. D

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Current-carrying string-loop dynamics is studied in the Kerr spacetimes. With attention concentrated to the axisymmetric motion of string loops around symmetry axis of both black-hole (BH) and naked singularity (NS) spacetimes, it is shown that the resulting motion is governed by the presence of an outer tension barrier and an inner angular momentum barrier that are influenced by the BH or NS spin. We classify the string dynamics according to properties of the energy boundary function (effective potential) for the string loop motion. We have found that for NS there exist new types of energy boundary function, namely those with off-equatorial minima. Conversion of the energy of the string oscillations to the energy of the linear translational motion has been studied. Such a transmutation effect is much more efficient in the NS spacetimes because lack of the event horizon. For BH spacetimes efficiency of the transmutation effect is only weakly spin dependent. Transition from regular to chaotic regime of the string-loop dynamics is examined and used for explanation of the string-loop motion focusing problem. Radial and vertical frequencies of small oscillations of string loops near minima of the effective potential in the equatorial plane are given. These can be related to high-frequency quasi-periodic oscillations observed near black holes.

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“…implied by the condition H = 0, given by reparameterization invariance of the action (10). We can make the rescaling E b → E b /µ and J → J/ √ µ, assuming µ > 0.…”

Section: Energy Boundary Functionmentioning

confidence: 99%

Dynamics of current-carrying string loops in the Kerr naked-singularity and black-hole spacetimes

Kološ

Stuchlík

2013

Phys. Rev. D

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“…There is an important possible astrophysical relevance of the current-carrying string loops [1] as they could in a simplified way represent plasma that exhibits associated string-like behavior via dynamics of the magnetic field lines in the plasma [7,8] or due to thin isolated flux tubes of magnetized plasma that could be described by an one-dimensional string [9][10][11]. Motion of electrically charged string loops in combined external gravitational and electromagnetic fields has been recently studied for a Schwarzschild black hole immersed in a homogeneous magnetic field [12].…”

Section: Introductionmentioning

confidence: 99%

String loops oscillating in the field of Kerr black holes as a possible explanation of twin high-frequency quasiperiodic oscillations observed in microquasars

Stuchlík

Kološ

2014

Phys. Rev. D

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Small oscillations of current-carrying string loops around stable equilibrium positions corresponding to minima of the effective potential in the equatorial plane of the Kerr black holes are studied using the perturbation method. In the lowest approximation, two uncoupled harmonic oscillators are obtained that govern the radial and vertical oscillations; the higher-order terms determine nonlinear phenomena and transition to chaotic motion through quasi-periodic stages of the oscillatory motion. The radial profiles of frequencies of the radial and vertical harmonic oscillations that are relevant also in the quasi-periodic stages of the oscillatory motion are given, and their properties in dependence on the spin of the black holes and the angular momentum and tension of the string loops are determined. It is shown that the radial profiles differ substantially from those corresponding to the radial and vertical frequencies of the geodetical epicyclic motion; however, they have the same mass-scaling and their magnitude is of the same order. Therefore, we are able to demonstrate that assuming relevance of resonant phenomena of the radial and vertical string-loop oscillations at their frequency ratio 3 : 2, the oscillatory frequencies of string loops can be well related to the frequencies of the twin high-frequency quasi-periodic oscillations (HF QPOs) observed in the microquasars GRS 1915+105, XTE 1550-564, GRO 1655-40. We can conclude that oscillating current-carrying string loops have to be considered as one of the possible explanations of the HF QPOs occurring in the field of compact objects.

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“…3.1. Moreover, the force equation (41) formally coincides with the one written for the charged test particles (34). However, here the gravitational potential Ψ is represented by the function containing a contribution from the specific enthalpy through the term w = ln h. Thus, in comparison with the gravitational potential Φ of the representation (25), this one is not of the pure geometry nature, but depends also on the fluid flow, possibly forming a structure.…”

Section: The W-force Representation Of the Modelmentioning

confidence: 95%

Charged fluids encircling compact objects: force representations and conformal geometries

Kovář¹,

Kojima²,

Slaný³

et al. 2020

Class. Quantum Grav.

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Charged fluids rotating around compact objects can form unique equilibrium structures when ambient large-scale electromagnetic fields combine with strong gravity. Equatorial as well as off-equatorial toroidal structures are among such figures of equilibrium with a direct relevance for astrophysics. To investigate their geometrical shapes and physical properties in the near-horizon regime, where effects of general relativity play a significant role, we commonly employ a scheme based on the energy-momentum conservation written in a standard representation. Here, we develop its interesting alternatives in terms of two covariant force representations, both based on a hypersurface projection of the energy-momentum conservation. In a proper hypersurface, space-like forces can be defined, following from a decomposition of the fluid four-acceleration. Each of the representations provides us with an insight into properties of the fluid flow, being well reflected in related conformal hypersurface geometries; we find behaviour of centrifugal forces directly related to geodesics of these conformal hypersurfaces and their embedding diagrams. We also reveal correspondence between the charged fluid flow world-lines from an ordinary spacetime, and world-lines determined by a charged test particles equation of motion in a conformal spacetime.

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Dynamics of an electric current-carrying string loop near a Schwarzschild black hole embedded in an external magnetic field

Cited by 18 publications

References 41 publications

Dynamics of current-carrying string loops in the Kerr naked-singularity and black-hole spacetimes

Dynamics of current-carrying string loops in the Kerr naked-singularity and black-hole spacetimes

String loops oscillating in the field of Kerr black holes as a possible explanation of twin high-frequency quasiperiodic oscillations observed in microquasars

Charged fluids encircling compact objects: force representations and conformal geometries

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