Related papers: Static horizons in cosmology
It is shown that in the extreme limit with a zero surface gravity but nonzero local temperature the limiting metric of a generic static black hole is determined by a metric induced on a horizon and one function of two coordinates,…
We consider accelerated black hole horizons with and without defects. These horizons appear in the $C$-metric solution to Einstein equations and in its generalization to the case where external fields are present. These solutions realize a…
We review recent results on the existence of static black holes without spatial isometries in four spacetime dimensions and propose a general framework for their study. These configurations are regular on and outside a horizon of spherical…
In recent years there have been many studies on exactly solvable black hole mergers, based on a model by Emparan and Martinez where the mass of one black hole is blown up to infinity. Here we replace the large black hole by a cosmological…
String theory and ``quantum geometry'' have recently offered independent statistical mechanical explanations of black hole thermodynamics. But these successes raise a new problem: why should models with such different microscopic degrees of…
General Relativity allows for a cosmological constant ($\Lambda$) which has inspired models of cosmic Inflation and Dark Energy. We show instead that $r_\Lambda = \sqrt{3/\Lambda}$ corresponds to an event horizon: a causal boundary term in…
Black holes encountered in general relativity are characterized by spacetime singularities hidden within an event horizon. These singularities provide a key motivation to go beyond general relativity and look for regular black holes where…
We propose an effective model for an exponentially expanding universe in the brane-world scenario. The setup consists of a 5D black hole and a brane close to the black hole horizon. In case the brane acquires a specific configuration, which…
Previous work has shown that static multi-black hole solutions of higher-dimensional Einstein-Maxwell theory do not possess smooth horizons. We show that the lack of smoothness is worse than previously demonstrated. We consider solutions…
The theoretical properties of the black holes (BHs) and of the universe were derived from a unified relativistic theory based on a generalization of local relativity for nonlocal cases in gravitational fields and a quantized standing wave…
Working in a semi-classical setting, we consider solutions of the Einstein equations that exhibit light trapping in finite time according to distant observers. In spherical symmetry, we construct near-horizon quantities from the assumption…
A rigidity theorem that applies to smooth electrovac spacetimes which represent either (A) an asymptotically flat stationary black hole or (B) a cosmological spacetime with a compact Cauchy horizon ruled by closed null geodesics was given…
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…
Asymptotic symmetries are known to constrain the infrared behaviour of scattering processes in asymptotically flat spacetimes. By the same token, one expects symmetries of the black hole horizon to constrain near-horizon gravitational…
We study a minimal extension of a recently proposed modification of general relativity that draws on concepts from topological field theory to resolve aspects of the cosmological constant problem. In the original model, the field content of…
New approach to exact solvability of dilaton gravity theories is suggested which appeals directly to structure of field equations. It is shown that black holes regular at the horizon are static and their metric is found explicitly. If a…
We outline the class of globally regular spherically symmetric solutions to the minimally coupled GR equations asymptotically de Sitter in the origin and asymptotically Schwarzschild at infinity. A source term connects smoothly de Sitter…
We investigate the Schwarzschild-(anti) de Sitter spacetime with the anisotropic metric ansatz. The Wheeler-DeWitt equation for such a metric is solved numerically. In the presence of the cosmological constant $\Lambda$, we show that two…
In the de Sitter-invariant approach to gravitation, all solutions to the gravitational field equations are spacetimes that reduce locally to de Sitter. Consequently, besides including an event horizon, the de Sitter-invariant black hole…
In general relativity without a cosmological constant, a classical theorem due to Hawking states that stationary black holes must be topologically spherical. This result is one of the several ingredients that collectively imply the…