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It has long been known that, in higher-dimensional general relativity, there are black hole solutions with an arbitrarily large angular momentum for a fixed mass. We examine the geometry of the event horizon of such ultra-spinning black…
It is well-known that a particle falling into a black hole will definitely reach the center in finite proper time if it enters the sphere of radius $3r_{s}/2$ where $r_{s}$ is the Schwarzschild radius. It is usually assumed that once the…
Hawking radiation from a black hole can be viewed as quantum tunneling of particles through the event horizon. Using this approach we provide a general framework for studying corrections to the entropy of black holes beyond semiclassical…
We present new self-gravitating solutions in five dimensions that describe circular strings, i.e., rings, electrically coupled to a two-form potential (as e.g., fundamental strings do), or to a dual magnetic one-form. The rings are…
We construct the general solution for non-extremal charged rotating black holes in five-dimensional minimal gauged supergravity. They are characterised by four non-trivial parameters, namely the mass, the charge, and the two independent…
Rapidly rotating Kerr black holes can accelerate particles to arbitrarily high energy if the angular momentum of the particle is fine-tuned to some critical value. This phenomenon is robust as it is founded on the basic properties of…
Assessing the stability of higher-dimensional rotating black holes requires a study of linearized gravitational perturbations around such backgrounds. We study perturbations of Myers-Perry black holes with equal angular momenta in an odd…
The purpose of this chapter is to provide an overview of the exciting field of black hole quasi-normal modes and its capabilities to test general relativity in the 21st century. After motivating this line of research, we provide a…
According to General Relativity, astrophysical black holes are described by a small number of parameters. Apart from the mass of the black hole (M), among the most interesting characteristics is the spin (a), which determines the degree of…
We show how the motion of a charged particle near the horizon of an extreme Reissner-Nordstrom black hole can lead to different forms of conformal mechanics, depending on the choice of the time coordinate.
We investigate the motion of a magnetized particle orbiting around a black hole in braneworld placed in asymptotically uniform magnetic field. The influence of brane parameter on effective potential of the radial motion of magnetized…
The Kerr-Newman metric is used to discuss the averagely measured speed of light along the radial direction at the black hole from a weak-gravitation reference frame such as an observer on Earth. The velocity equation of light at the black…
The Hawking-Penrose singularity theorem states that a singularity forms inside a black hole in general relativity. To remove this singularity one must resort to a more fundamental theory. Using a corrected dynamical equation arising in loop…
Physically relevant solutions in general relativity often contain spacetime singularities, which are typically interpreted as a sign of breakdown of the theory at high densities/curvatures. Hence, there has been a growing interest in…
The effect of gravitational radiation reaction on orbits around a spinning black hole is analyzed. Such orbits possess three constants of motion: $\iota$, $e$, and $a$, which correspond, in the Newtonian limit of the orbit being an ellipse,…
We discuss constants of motion of a particle under an external field in a curved spacetime, taking into account the Hamiltonian constraint which arises from reparametrization invariance of the particle orbit. As the necessary and sufficient…
We study eccentric equatorial orbits of a test-body around a Kerr black hole under the influence of gravitational radiation reaction. We have adopted a well established two-step approach: assuming that the particle is moving along a…
The rotating loop quantum gravity black hole is a newly proposed non-singular black hole, which eliminates spacetime singularities when a regularization parameter is introduced through loop quantum corrections. This parameter is expected to…
The motion of superluminal particles in the gravitational field of a non-rotating black hole is analyzed. The relativistic Hamilton-Jacobi equation is solved for particles with imaginary rest mass. It is shown that there are no stable…
The radial motion of photons emitted near the horizon of a black hole that evaporates at a steady rate is examined. The space-time of the black hole is generated using non-orthogonal coordinates. It is shown that some photons that are…