Related papers: Superradiance without event horizons in General Re…
The event horizon of a black hole in general relativity absorbs all infalling radiation. Any observation of the contrary would immediately challenge the expectation that astrophysical black holes are described by the vacuum Kerr geometry.…
Recent advances in the X-ray and soft gamma-ray observations of accreting black holes and microquasars, in particular, are reviewed. The radiative processes responsible for the emission are discussed briefly. The hybrid thermal/nonthermal…
Violating Lorentz-invariance, and so implicitly permitting some form of superluminal communication, necessarily alters the notion of a black hole. Nevertheless, in both Einstein-{\AE}ther gravity, and Ho\v{r}ava-Lifshitz gravity, there is…
In the present paper some consequences of the hypothesis that the supermassive compact object in the Galaxy centre relates to a class of objects without event horizon are examined. The possibility of the existence of such objects was…
Gravitational waves emitted from the gravitational ringing of supermassive black holes are important targets to test general relativity and probe the matter environment surrounding such black holes. The main components of the ringing…
We establish a generic, fully-relativistic formalism to study gravitational-wave emission by extreme-mass-ratio systems in spherically-symmetric, non-vacuum black-hole spacetimes. The potential applications to astrophysical setups range…
We find radiation in an infalling frame and present an explicit analytic evidence of the failure of no drama condition by showing that an infalling observer finds an infinite negative energy density at the event horizon. The negative and…
Analogical thinking is a valuable tool in theoretical physics, since it allows us to take the understanding we have developed in one system and apply it to another. In this thesis, we study the analogy between two seemingly unlikely…
We simulate high-energy scattering of equal-mass, nonspinning black holes endowed with like charges in full general relativity while varying the impact parameter $b$. We show that electrodynamics does not suppress zoom-whirl orbits for at…
Black holes are presumed to have an ideal ability to absorb and keep matter. Whatever comes close to the event horizon, a boundary separating the inside region of a black hole from the outside world, inevitably goes in and remains inside…
The spin energy extraction from a rotating black hole by amplification of scalar waves inside superradiance resonance wedge cavity (ring), followed by jet formation via magnetic reconnection assisted by the amplified scalar fields, is…
Hawking radiation can usefully be viewed as a semi-classical tunnelling process that originates at the black hole horizon. The conservation of energy implies the effect of self-gravitation. For a static black hole, a generalized Painleve…
Recently, it has been reported that black holes (BHs) sourced by nonlinear electrodynamics (NED) can trigger unbounded superradiance, i. e., the total absorption cross section -- the ratio between the absorbed flux and the incident flux of…
Particles or waves scattered from a rotating black hole can be amplified through the process of Penrose superradiance, though this cannot currently be observed in an astrophysical setting. However, analogue gravity studies can create…
We study gravitational and electromagnetic radiation generated by uniformly accelerated charged black holes in anti-de Sitter spacetime. This is described by the C-metric exact solution of the Einstein-Maxwell equations with a negative…
We study gravitational wave emission, zoom-whirl behavior and the resulting spin of the remnant black hole in highly boosted collisions of equal-mass, non spinning black-hole binaries with generic impact parameter.
We compute the absorption cross section and the total power carried by gravitons in the evaporation process of a higher-dimensional non-rotating black hole. These results are applied to a model of extra dimensions with standard model fields…
We study the perception of Hawking radiation by different observers outside a black hole. The analysis is done in terms of an effective-temperature function that varies along the trajectory of each observer. The vacuum state of the…
Gravitons radiated from light, evaporating black holes contribute to the stochastic background of gravitational waves. The spectrum of such emission depends on both the mass and the spin of the black holes, as well as on the redshifting…
The destruction of a regular black hole event horizon might provide us the possibility to access regions inside black hole event horizon. This paper investigates the possibility of overcharging a charged Taub-NUT regular black hole via the…