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We investigate the geometrical structure of Vaidya's spacetime in the case of a white hole with decreasing mass, stabilising to a black hole in finite or infinite time or evaporating completely. Our approach relies on a detailed analysis of…
We construct analytical models to study the critical phenomena in gravitational collapse of the Husain-Martinez-Nunez massless scalar field. We first use the cut-and-paste technique to match the conformally flat solution ($c=0$ ) onto an…
We study the method of calculating the Hawking radiation via gravitational anomalies in gravitational backgrounds of constant negative curvature. We apply the method to topological black holes and also to topological black holes conformally…
The scalar wave equation is considered in the background of a charged Vaidya metric in double null coordinates $(u,v)$ describing a non-stationary charged black hole with varying mass $m(v)$ and charge $q(v)$. The resulting time-dependent…
We examine spherical gravitational collapse of a matter model with vanishing radial pressure and non-zero tangential pressure. It is seen analytically that the collapsing cloud either forms a black hole or disperses depending on values of…
The low-energy dynamics of any system admitting a continuum of static configurations is approximated by slow motion in moduli (configuration) space. Here, following Ferrell and Eardley, this moduli space approximation is utilized to study…
This work deals with the formation of black hole in bidimensional dilaton gravity coupled to scalar matter fields. We investigate two scalar matter systems, one described by a sixth power potential and the other defined with two scalar…
We study Hawking radiation on a Vaidya space-time with a gravitational collapse followed by evaporation. The collapsing body is a null thin-shell and the evaporation is induced by a negative energy collapsing null-shell. This mimics the…
We study the spherically symmetric collapse of a cloud of dust in VCDM, a class of gravitational theories with two local physical degrees of freedom. We find that the collapse corresponds to a particular foliation of the Oppenheimer-Snyder…
We study the stochastic background of gravitational waves which accompany the sudden freeze-out of dark matter triggered by a cosmological first order phase transition that endows dark matter with mass. We consider models that produce the…
We derive two-dimensional (2D) solutions of a generic dilaton gravity model coupled with matter, which describe D-dimensional static black holes with pointlike sources. The equality between the mass M of the D-dimensional gravitational…
With the gauge-invariant perturbation theory, we study the effects of the stellar magnetic fields on the polar gravitational waves emitted during the homogeneous dust collapse. We found that the emitted energy in gravitational waves depends…
We present numerical three-body experiments that include the effects of gravitational radiation reaction by using equations of motion that include the 2.5-order post-Newtonian force terms, which are the leading order terms of energy loss…
The interior of gravitationally collapsed objects in alternate theories of gravity in which event horizons and singularities do not occur in strong field gravity were generically investigated. These objects, called red holes, were found to…
This work is devoted to investigate some consequences of black holes physics beyond the domain of general relativity, mainly in effective extra dimensional models. The investigation is carried along three gravitational effects, namely the…
Gravitational wave solutions to Einstein's equations and their generation are examined in D-dimensional flat spacetimes. First the plane wave solutions are analyzed; then the wave generation is studied with the solution for the metric…
The gravitational field of a laser pulse, although not detectable at the moment, comes with a peculiar feature which continues to attract attention; cause and effect propagate with the same speed, that of light. A particular result of this…
This paper studies gravitational collapse of a complex scalar field at the threshold for black hole formation, assuming that the collapse is spherically symmetric and continuously self-similar. A new solution of the coupled Einstein-scalar…
Interested in the collapse of a radiating star, we study the temporal evolution of a fluid with heat flux and bulk viscosity, including anisotropic pressure. As a starting point, we adopt an initial configuration that satisfies the…
A pair of wave equations is presented for the gravitational and electromagnetic perturbations of a charged black hole. One of the equations is uncoupled and determines the propagation of the electromagnetic perturbation. The other is for…