Related papers: Cosmological tests of the gravastar hypothesis
Gravastar models have recently been proposed as an alternative to black holes, mainly to avoid the pro\-ble\-ma\-tic issues associated with event horizons and singularities. In this work, a regular variety of gravastar models within the…
A solution to Einstein's field equations via the Friedman equations is shown to produce a cosmological model that is in exact agreement with the measurements made by the dark energy astronomers. All the essential physical parameters are…
Production of gravitational vacuum defects and their contribution to the energy density of our Universe are discussed. These topological microstructures (defects) could be produced in the result of creation of the Universe from "nothing"…
In this paper, we construct two spherically symmetric thin-shell gravastar models within a BTZ geometry with minimum length. Therefore, in the inner region of the gravastar, we consider an anti- de Sitter metric with minimum length. Thus,…
The dS bubbles can nucleate spontaneously during inflation, and will be stretched by the cosmological expansion to astrophysical scale. We report on a novel phenomenon that such a bubble might develop into a gravastar (an ultra-compact…
An epoch known as cosmological stasis may have taken place in the early Universe. During matter-radiation stasis, a population of non-relativistic particles with different masses gradually decay into relativistic particles, and the…
Two of the most fundamental problems at the nexus of Einstein's classical General Relativity (GR) and Quantum Field Theory (QFT) are: (1) complete gravitational collapse, presumed in classical GR to lead to a Black Hole (BH) horizon and…
An algorithm is described for evolving the phase-space density of stars or compact objects around a massive black hole at the center of a galaxy. The technique is based on numerical integration of the Fokker-Planck equation in…
It was recently suggested that the cosmological constant problem as viewed in a non-perturbative framework is intimately connected to the choice of time and a physical Hamiltonian. We develop this idea further by calculating the…
In the present work, we have discussed the four dimensional spherically symmetric steller system in the framework of modified $f(T)$ gravity theory with electro-magnetic field. The field equations have been written for two cases, either…
We challenge a widely accepted assumption of observational cosmology: that successful reconstruction of observed galaxy density fields from measured galaxy velocity fields (or vice versa), using the methods of gravitational instability…
Although previous results have ruled out the possibility of a static horizon in cosmology, we present black hole and white hole metrics that retain static horizons while reproducing cosmological behavior at large distances. Using an…
Pair-instability should prevent the direct formation of black holes above about $50M_\odot$ creating a pair-instability mass gap. Yet gravitational-wave observations have detected black holes in this mass range. These systems can be…
Using the results of a numerical simulation which follows the evolution, metal enrichment and energy deposition of both Population III and Population II stars, we predict the redshift dependence of the formation rate of black hole remnants…
The energy densities of dark matter (DM) and dark energy (DE) are of the same order at the present epoch despite the fact that both these quantities have contrasting characteristics and are presumed to have evolved distinctively with cosmic…
We systematically study spherically symmetric static spacetimes filled with a fluid in the Horava-Lifshitz theory of gravity with the projectability condition, but without the detailed balance. We establish that when the spacetime is…
We investigate the cosmological production of gravitational waves in a nonsingular flat cosmology powered by a "running vacuum" energy density described by $\rho_{\Lambda}\equiv\rho_{\Lambda}(H)$, a phenomenological expression potentially…
The Galactic massive black hole (MBH), with a mass of Mbh=3.6\times10^6 Solar masses, is the closest known MBH, at a distance of only 8 kpc. The proximity of this MBH makes it possible to observe gravitational waves from stars with periapse…
Recent work has suggested that black holes (BHs) could be cosmologically coupled to the accelerated expansion of the universe, potentially becoming a candidate for dark energy. This would imply BH mass growth following the cosmological…
Gravitational-wave astronomy has the potential to explore one of the deepest and most puzzling aspects of Einstein's theory: the existence of black holes. A plethora of ultracompact, horizonless objects have been proposed to arise in models…