A. Masoud Ghezelbash

We extend the black hole holography to the case of an asymptotically anti-de Sitter (AdS) rotating charged black holes in [ ] gravity, where [ ] is a constant. We find that the scalar wave radial equation at the near-horizon region implies the existence of the 2D conformal symmetries. We show that by choosing proper central charges for the dual CFT, we produce exactly the macroscopic Bekenstein–Hawking entropy from the microscopic Cardy entropy for the dual CFT. These observations suggest that the rotating charged AdS black hole in [ ] gravity is dual to a 2D CFT at finite temperatures.

We express a new mathematical Taub-NUT like black-hole solution in f ( R ) gravity. This solution is found to have a non constant Ricci scalar and corresponds to an extension of the δ = − 1 / 2 case of the Clifton–Barrow metric. Within the context of this space-time we examine various limit, thermodynamic quantities and non-charged particle trajectories. In addition we find an Eguchi–Hanson type-II f ( R ) regime related to the found solution.

We find a new class of exact solutions for rotating black holes in [ ] gravity in presence of imperfect fluid. We find that the exact solutions are holographically dual to a hidden conformal field theory (CFT). Moreover, we consider another class of exact solutions for rotating black holes in [ ] gravity, which is obtained through a Lorentz boost transformation on a static spherical symmetry solutions in [ ] gravity. We also find that the exact boosted solutions are holographically dual to a hidden conformal field theory. Comparing the CFT temperatures and the mode numbers of the two CFTs, we suggest a conjecture that, “Two identical rotating black holes (the same mass and the horizon) in[ ] theory could be distinguished by looking at their dual CFT temperatures, and the dual CFT mode numbers. The rotating black hole in the presence of matter has higher CFT temperatures and higher CFT mode numbers, compared to the vacuum boosted rotating black hole”.

We find new classes of the dynamical black hole solutions in five- or higher-dimensional Einstein–Maxwell-dilaton theory, in which the dilaton field interacts nontrivially with the Maxwell field, and the cosmological constant, with two arbitrary coupling constants. The solutions which are nonstationary, and almost conformally regular everywhere, are constructed by embedding the four-dimensional self-dual geometries. We consider three different situations, where the two coupling constants are not equal, are nonzero equal and finally both are zero. We also consider the cases where one of the metric functions, depends on one coordinate only, and another interesting case where it depends on two spatial coordinates. We also find that the cosmological constant can take all possible negative, zero and positive values, hence our solutions are asymptotically anti-de Sitter, flat and de Sitter. We discuss the properties of the solutions which are the analytic description of coalescing black holes in any dimensions, greater or equal to five.

We construct exact analytical Taub-NUT solutions in the context of f(T) gravity. We study the physical properties of the solutions, and compare them with those of the Taub-NUT solution in Einstein gravity.

We construct new classes of the dynamical black hole solutions in five or higher dimensional Einstein–Maxwell theory, coupled to a dilaton field, in the presence of an arbitrary cosmological constant. The dilaton field interacts non-trivially with the Maxwell field, as well as the cosmological constant, with two arbitrary coupling constants. The solutions are non-stationary, and almost conformally regular everywhere. To construct the solutions, we use the four-dimensional Bianchi type IX geometry, as the base space. We find three different classes of solutions, based on the values of the coupling constants. We notice that our solutions could be asymptotically de-Sitter, anti-de-Sitter or flat. We find the relevant quantities of the solutions, and discuss the properties of the solutions.

We construct some new brane solutions in M-theory, based on the minimal surfaces. In particular, we consider the anti-self-dual Nutku geometry, and embed it in the membranes and five-branes of the eleven-dimensional supergravity. We explicitly show that the solutions preserve eight supersymmetries. Upon compactification on a circle, we find fully localized intersecting brane systems. We also discuss the T-dual and the decoupling limits of the solutions.

In this article, we consider a class of four-dimensional Einstein-Maxwell theory which is coupled nonminimally to a scalar field and the Gauss-Bonnet invariant. We mainly use the numerical methods to find the solutions to the theory, with the Newman, Tamburino, Unti (NUT) twist. We find explicitly the numerical solutions to all of the field equations. To find the appropriate consistent numerical solutions, we use the perturbative expansion of the fields asymptotically, as well as near horizon. The solutions describe the NUTty black holes with the scalar charge which also depend explicitly on the values of the nonminimal coupling constants. We provide a detailed numerical analysis of the solutions in terms of all existing parameters of the theory.

In this article, we consider a class of four-dimensional Einstein-Maxwell theory which is coupled non-minimally to a scalar field and the Gauss-Bonnet invariant. We mainly use the numerical methods to find the solutions to the theory, with the NUT twist. We find explicitly the numerical solutions to all of the field equations. To find the appropriate consistent numerical solutions, we use the the perturbative expansion of the fields asymptotically, as well as near horizon. The solutions describe the NUTty black holes with the scalar charge which also depend explicitly on the values of the non-minimal coupling constants. We provide a detailed numerical analysis of the solutions in terms of all existing parameters of the theory.