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Tashkent, Uzbekistan

Rahimov O.G.,Institute of Nuclear Physics of Uzbekistan | Rahimov O.G.,Ulugh Begh Astronomical Institute
Modern Physics Letters A | Year: 2011

We investigate the motion of a magnetized particle orbiting around a black hole in braneworld immersed in asymptotically uniform magnetic field. The influence of brane parameter on effective potential of the radial motion of magnetized spinning particle around the braneworld black hole using Hamilton-Jacobi formalism is studied. It is found that circular orbits for photons and slowly moving particles may become stable near r = 3M. It was argued that the radii of the innermost stable circular orbits are sensitive on the change of brane parameter. Similar discussion without Weil parameter has been considered by de Felice et al. in Refs. 1 and 2. © 2011 World Scientific Publishing Company.


Hakimov A.,Ulugh Begh Astronomical Institute | Atamurotov F.,Institute of Nuclear Physics of Uzbekistan | Atamurotov F.,Inha University
Astrophysics and Space Science | Year: 2016

We study gravitational lensing in the vicinity of a massive object described by non-Schwarzschild geometry surrounded by a homogeneous plasma. The expression for the deflection angle in a non-Schwarzschild space-time in the weak field regime in the presence of plasma have been derived. It has been shown that the obtained deflection angle depends on (i) the frequency of the electromagnetic wave, due to the dispersion properties of the plasma; (ii) the gravitational mass  (Formula presented.) ; and (iii) deformation parameter (Formula presented.) of the gravitational lens. Moreover, the influence of deformation parameter of the gravitational lens and plasma frequency on the magnification of brightness of the source star has been studied in the case of microlensing. © 2016, Springer Science+Business Media Dordrecht.


Tursunov A.,Silesian University in Opava | Tursunov A.,Institute of Nuclear Physics of Uzbekistan | Kolos M.,Silesian University in Opava | Stuchlik Z.,Silesian University in Opava | And 2 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

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∼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. © 2014 American Physical Society.


Morozova V.S.,Max Planck Institute For Gravitationsphysik | Morozova V.S.,Institute of Nuclear Physics of Uzbekistan | Ahmedov B.J.,Institute of Nuclear Physics of Uzbekistan | Ahmedov B.J.,Ulugh Begh Astronomical Institute | And 3 more authors.
Astrophysics and Space Science | Year: 2013

We study gravitational lensing in the vicinity of a slowly rotating massive object surrounded by a plasma. We have studied two effects: (i) the influence of the frame dragging on the deflection angle of the light ray in the presence of plasma (ii) Faraday rotation of the polarization plane of the light. We derive the expression for the lensing angle in a non-diagonal space-time in the weak field regime in the presence of plasma and discuss it for the spacetime metric of the slowly rotating object. The obtained deflection angle depends on (i) the frequency of the electromagnetic wave, due to the dispersion properties of the plasma; (ii) the gravitational mass M; and (iii) the angular momentum J of the gravitational lens. We studied the influence of rotation of the gravitational lens on the magnification of brightness of the source star in the case of microlensing and have shown that it is negligibly small. For the completeness of our study the effect of the Faraday rotation of the polarization plane is considered. © 2013 Springer Science+Business Media Dordrecht.


Tursunov A.,Institute of Nuclear Physics of Uzbekistan | Tursunov A.,Ulugh Begh Astronomical Institute | Tursunov A.,Max Planck Institute For Gravitationsphysik | Kolos M.,Silesian University in Opava | And 4 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

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. © 2013 American Physical Society.

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