Related papers: Black hole event horizons are cosmologically coupl…
The analytic structure of solutions to the Klein-Gordon equation in a black hole background, as represented by monodromy data, is intimately related to black hole thermodynamics. It encodes the "hidden conformal symmetry" of a non-extremal…
This study examines the gravitational and thermodynamic properties of static, spherically symmetric black holes within cosmic voids -- vast underdense regions of the universe. By deriving a novel solution based on a universal density…
By incorporating the holographic principle in a time-depending Lambda-term cosmology, new physical bounds on the arbitrary parameters of the model can be obtained. Considering then the dark energy as a purely geometric entity, for which no…
Black and white holes play remarkably contrasting roles in general relativity versus observational astrophysics. While there is overwhelming observational evidence for the existence of compact objects that are "cold, dark, and heavy", which…
Astronomical observations have confirmed the existence of BHs and the occurrence of the Big Bang event to beyond any reasonable doubt. While quantum field theory and general theory of relativity predict the mass-spectrum of BHs to be…
It is shown that only particular kinds of matter (in terms of the "radial" pressure to density ratio $w$) can coexist with Killing horizons in black-hole or cosmological space-times. Thus, for arbitrary (not necessarily spherically…
Constraints on the geometry of a static spherically symmetric black hole are obtained by requiring the spacetime curvature to be analytic at the event horizon. For a zero temperature black hole further constraints are obtained by also…
To explain black hole thermodynamics in quantum gravity, one must introduce constraints to ensure that a black hole is actually present. I show that for a large class of black holes, such ``horizon constraints'' allow the use of conformal…
It is common knowledge that black holes necessarily contain a region where general relativity breaks down, due to the inevitable formation of either a curvature singularity or a Cauchy horizon. In this work we challenge this view by…
Supermassive black hole (SMBH) growth plausibly occurs via runaway astrophysical black hole mergers in nuclear star clusters that form intermediate mass black hole seeds at high redshifts. Such a model yields an order-of-magnitude higher…
The relation between event horizons and trapping horizons is investigated in a number of different situations with emphasis on their role in thermodynamics. A notion of constant change is introduced that in certain situations allows the…
We find black hole solutions to Euclidean 2+1 gravity coupled to a relativistic particle which have a dynamical conical singularity at the horizon. These solutions mimic the tree level contribution to the partition function of gravity…
Infinitely cyclic cosmology is often frustrated by the black hole problem. It has been speculated that this obstacle in cyclic cosmology can be removed by taking into account a peculiar cyclic model derived from loop quantum cosmology or…
We use ray-tracing techniques to determine the evolution of the event horizon of a large black hole that ``gobbles'' a tiny, traversable wormhole. This calculation has physical meaning in the extreme mass ratio limit. Two setups are…
Two particles can collide inside a nonextremal black hole in such a way that the energy E_{c.m.} in their centre of mass frame becomes as large as one likes. We show that this effect can be understood with the help of a simple analogy with…
A simple argument is given that a traversable Cauchy horizon inside a black hole is incompatible with unitary black hole evolution. The argument assumes the validity of black hole complementarity and applies to a generic black hole carrying…
Black hole horizon is usually defined as the limit for existence of timelike worldline or when a spatially bound surface turns oneway (it is crossable only in one direction). It would be insightful and physically appealing to find its…
We propose here that the well-known black hole paradoxes such as the information loss and teleological nature of the event horizon are restricted to a particular idealized case, which is the homogeneous dust collapse model. In this case,…
Single pulse of null dust and colliding null dusts both transform a regular horizon into a space-like singularity in the space of colliding waves. The local isometry between such space-times and black holes extrapolates these results to the…
Black holes pose a serious problem in the cyclic or oscillating cosmology. It is speculated that, in the cyclic universe with phantom turnarounds, black holes will be torn apart by the phantom energy before turnaround before they can create…