Related papers: Black Hole versus Naked Singularity via Axial Pert…
It was long believed that the singularity inside a realistic, rotating black hole must be spacelike. However, studies of the internal geometry of black holes indicate a more complicated structure is typical. While it seems likely that an…
Recently, the possibility was pointed out by one of the present authors and his collaborators that an effective naked singularity referred to as "a visible border of spacetime" is generated by high-energy particle collision in the context…
We consider spherically-symmetric black holes in semiclassical gravity. For a collapsing radiating thin shell we derive a sufficient condition on the exterior geometry that ensures that a black hole is not formed. This is also a sufficient…
We explore the quantum nature of black holes by introducing an effective framework that takes into account deviations from the classical results. The approach is based on introducing quantum corrections to the classical Schwarzschild…
The approximate renormalized stress-energy tensor of the quantized massive conformally coupled scalar field in the spacetime of electrically charged nonlinear black hole is constructed. It is achieved by functional differentiation of the…
We consider the observational signatures of reflective naked singularities as seen by the current and next-generation Event Horizon Telescope (EHT). The reflective naked singularities lead to a distinctive morphology of their accretion disk…
A charged black hole can emit charged particles via two independent mechanisms: the Hawking radiation and the Schwinger effect, which are intertwined in the radiation spectrum. In this paper, we will show that the two effects can be…
We consider a gravitating system consisting of a scalar field minimally coupled to gravity with a self-interacting potential and an U(1) electromagnetic field. Solving the coupled Einstein-Maxwell-scalar system we find exact hairy charged…
The black hole of the widely used ordinary 2d--dilaton model (DBH) deviates from the Schwarzschild black hole (SBH) of General Relativity in one important feature: Whereas non-null extremals or geodesics show the expected incompleteness…
By using the gedanken experiments suggested by Bekenstein and Rosenzweig, we have shown that nonextremal Reissner-Nordstrom black hole cannot turn into extremal one by assimilating infalling charged particle and charged spherical shell.
The existence of curvature singularities and the information and firewall paradoxes are significant problems for the conventional black hole model. The black mirror provides a CPT-symmetric alternative to the classical description. We show…
The superradiant stability of higher dimensional non-extremal Reissner-Nordstrom black hole under charged massive scalar perturbation is analytically studied. We extend our previous studies of four- and five-dimensional non-extremal…
We investigate chaotic dynamics in extremal black holes by analyzing the motion of massless particles in both Reissner-Nordstr\"{o}m and Kerr geometries. Two complementary approaches (i) taking the extremal limit of non-extremal solutions…
An analog of black hole can be realized in the low-temperature laboratory. The horizon can be constructed for the `relativistic' ripplons (surface waves) living on the brane. The brane is represented by the interface between two superfluid…
A class of nonstationary spacetimes is obtained by means of a conformal transformation of the Schwarzschild metric, where the conformal factor $a(t)$ is an arbitrary function of the time coordinate only. We investigate several situations…
Using $N=1+1$ supersymmetric extension of the three-dimensional gravity with torsion, we show that a generic black hole has no exact supersymmetries, the extremal black hole has only one, while the zero-energy black hole has two. Combining…
It has been shown that black holes could be used as particle accelerators to create arbitrarily high center-of-mass (CM) energy if certain critical conditions are satisfied. Most studies so far are confined in four-dimensional spacetimes.…
A Reissner-Nordstr\"{o}m black hole (RNBH) enclosed in a cavity is known to be superradiantly unstable to charged scalar perturbations below a critical frequency. Inspired by the emergence of the QCD axion as a prominent dark matter…
It is argued that the qualitative features of black holes, regarded as quantum mechanical objects, depend both on the parameters of the hole and on the microscopic theory in which it is embedded. A thermal description is inadequate for…
In this paper, we derive the solutions of orbit equations for a class of naked singularity spacetimes, and compare these with timelike orbits, that is, particle trajectories in the Schwarzschild black hole spacetime. The Schwarzschild and…