We derive the system of equations describing the time dependent twisted accretion disc around a Kerr black hole (twist equations). The post-Newtonian corrections to the equations of motion and effects of the gravitomagnetic force are taken into account. We show that introduction of appropriate coordinate system greatly simplifies the derivation of equations and allows to consider sufficiently l...

We study phases of five-dimensional three-charge black holes with a circle in their transverse space. In particular, when the black hole is localized on the circle we compute the corrections to the metric and corresponding thermodynamics in the limit of small mass. When taking the near-extremal limit, this gives the corrections to the finite entropy of the extremal three-charge black hole as a ...

We criticize and generalize some properties of Nöther charges presented in a paper by V. Iyer and R. M. Wald and their application to entropy of black holes. The first law of black holes thermodynamics is proven for any gauge-natural field theory. As an application charged Kerr-Newman solutions are considered. As a further example we consider a (1 + 2) black hole solution. 1

When the term " black hole " was originally coined in 1968, it was immediately conjectured that the only pure vacuum equilibrium states were those of the Kerr family. Efforts to confirm this made rapid progress during the " classical phase " from 1968 to 1975, and some gaps in the argument have been closed during more recent years. However the presently available demonstration is still subject ...

We present a static solution for d = 2 critical string theory including the tachyon T but not its potential V (T ). This solution thus incorporates tachyon back reaction and, when T = 0, reduces to the black hole solution. When T 6= 0 one finds that (1) the Schwarzschild horizon of the above black hole splits into two, resembling Reissner-Nordstrom horizons and (2) the curvature scalar develops...

We study the evolution of strings in the equatorial plane of a Kerr-Newmann black hole. Writing the equations of motion and the constraints resulting from Hamilton’s principle, three classes of exact solutions are presented, for a closed string, encircling the black-hole. They all depend on two arbitrary, integration functions and two constants. A process for extracting energy is examined for t...

We present a new stationary, asymptotically flat solution of 5D EinsteinMaxwell gravity describing a Saturn-like black object: a rotating black hole surrounded by a rotating dipole black ring. The solution is generated by combining the vacuum black Saturn solution and the vacuum black ring solution with appropriately chosen parameters. Some basic properties of the solution are analyzed and the ...

Dynamics of relativistic outflows along the rotation axis of a Kerr black hole is investigated using a simple model and the evolution of the speed of the flow relative to the ambient medium is studied. We assume that a flow clump is under the influence of the relativistic tidal force of the central source as well as the Lorentz force due to the large-scale electromagnetic field that is assumed ...