Related papers: Gravitationally Collapsing Dust in $(2+1)$ Dimensi…
In this talk, we discuss the possibility that the vacuum is dynamically determined in the history of the universe. The point is that some of the bubbles with a certain vacuum shrink by the evolution of the universe via gravity and may…
We construct an approximate solution which describes the gravitational emission from a naked singularity formed by the gravitational collapse of a cylindrical thick shell composed of dust. The assumed situation is that the collapsing speed…
The definition of matter states on spacelike hypersurfaces of a 1+1 dimensional black hole spacetime is considered. Because of small quantum fluctuations in the mass of the black hole, the usual approximation of treating the gravitational…
We consider gravitational collapse of a sphere of a fluid with torsion generated by spin, which forms a black hole. We use the Tolman metric and the Einstein$-$Cartan field equations with a relativistic spin fluid as a source. We show that…
We study the condition of black hole formation in five-dimensional space-time. We analytically solve the constraint equations of five-dimensional Einstein equations for momentarily static and conformally flat initial data of a spheroidal…
We study the gravitational collapse of two thin shells of matter, in asymptotically flat spacetime or constrained to move within a spherical box. We show that this simple two-body system has surprisingly rich dynamics, which includes prompt…
We argue that $(0,1)$ heterotic string models with 4 non-heterotic spacetime dimensions may provide an instability of the vacuum to gravitational polarization in globally strong gravitational fields. This instability would be triggered…
In this paper we consider dark matter particle annihilation in the gravitational field of black holes. We obtain exact distribution function of the infalling dark matter particles, and compute the resulting flux and spectra of gamma rays…
We study here the gravitational collapse of a matter cloud with a non-vanishing tangential pressure in the presence of a non-zero cosmological term. Conditions for bounce and singularity formation are derived for the model. It is also shown…
In the 1+1-dimensional dilatonic background of Callan et al. \cite{Callan1992}, we collide fields. Real and ghost fields are considered separately. The colliding ghost fields in the lineland creates particle-like wormholes. These…
If TeV-scale gravity describes nature, black holes will be produced in particle accelerators, perhaps even with impressive rates at the Large Hadron Collider. Their decays, largely via the Hawking process, will be spectacular. Black holes…
We show that ultra-massive spacetimes exist also in 2 + 1 dimensions with a positive cosmological constant {\Lambda} > 0. They can be created through the collapse of a spherical null dust shell. The exterior of the shell is then a Mess…
It is now known that when a massive star collapses under the force of its own gravity, the final fate of such a continual gravitational collapse will be either a black hole or a naked singularity under a wide variety of physically…
We examine the gravitational collapse and black hole formation of multiple non--spherical configurations constructed from Szekeres dust models with positive spatial curvature that smoothly match to a Schwarzschild exterior. These…
The formation and quantum mechanical evaporation of black holes in two spacetime dimensions can be studied using effective classical field equations, recently introduced by Callan {\it et al.} We find that gravitational collapse always…
We study how the presence of an area gap, different than zero, affects the gravitational collapse of a dust ball. The implementation of such discreteness is achieved through the framework of polymer quantization, a scheme inspired by loop…
Supermassive black holes (with $\mathrm{M_{BH} \sim 10^9 M_{\odot}}$) are observed in the first Gyr of the Universe, and their host galaxies are found to contain unexpectedly large amounts of dust and metals. In light of the two empirical…
We study the threshold of gravitational collapse in spherically symmetric spacetimes governed by the Einstein-Maxwell-Vlasov equations. We numerically construct solutions describing a collapsing distribution of charged matter that either…
We study the Einstein gravity and dust system in three spacetime dimensions as an example of a non-perturbative quantum gravity model with local degrees of freedom. We derive the Hamiltonian theory in the dust time gauge and show that it…
Exact solutions of Einstein's equations in 2+1-dimensional anti-de Sitter space containing any number of black holes are described. In addition to the black holes these spacetimes can possess ``internal'' structure. Accordingly the generic…