Related papers: Radiative gravastar with thermal spectrum; Sudden …
We study the quantum particle creation in a toy model of spherically symmetric gravitational collapse whose final product is not a black hole but a gravastar. Precedent studies revealed that even in the case of the gravitational collapse to…
Regular black holes and horizonless black-hole mimickers offer mathematically consistent alternatives to address the challenges posed by standard black holes. However, the formation mechanism of these alternative objects is still largely…
Black holes are normally and naturally associated to the end-point of gravitational collapse. Yet, alternatives have been proposed and a particularly interesting one is that of gravitational condensate stars, or gravastars. We here revisit…
Considering a Vaidya exterior spacetime, we study dynamical models of prototype gravastars, made of an infinitely thin spherical shell of a perfect fluid with the equation of state $p = \sigma$, enclosing an interior de Sitter spacetime. We…
Gravitational vacuum condensate stars, proposed as the endpoint of gravitational collapse consistent with quantum theory, are reviewed. Gravastars are cold, low entropy, maximally compact objects characterized by a surface boundary layer…
Direct observation of black holes is one of the grand challenges in astronomy. If there are super-compact objects which possess unstable circular orbits of photons, however, it may be difficult to distinguish them from black holes by…
Dynamical models of prototype gravastars made of anisotropic dark energy are constructed, in which an infinitely thin spherical shell of a perfect fluid with the equation of state $p = (1-\gamma)\sigma$ divides the whole spacetime into two…
The existence of cosmological compact objects with very strong gravity is a prediction of General Relativity and an exact solution of the Einstein equations. These objects are called black holes and recently we had the first observations of…
We study the collapse of a self-gravitating and radiating shell. Matter constituting the shell is quantized and the construction is viewed as a semiclassical model of possible black hole formation. It is shown that the shell internal…
Black holes (BHs) play a central role in physics. However, gathering observational evidence for their existence is a notoriously difficult task. Current strategies to quantify the evidence for BHs all boil down to looking for signs of…
Gravastars are configurations of compact singularity-free gravitational objects which are interesting alternatives to classical solutions in the strong gravitational field regime. Although there are no static star-like solutions of the…
The frozen star is a type of black hole mimicker: An ultracompact object whose exterior geometry resembles that of a general-relativistic black hole but differs in its matter composition and in the regularity of its interior geometry. It is…
In this paper, we investigate models of radiating gravastars with both isotropic and anisotropic interiors, incorporating various types of thin shell matter. For the isotropic interior case, we consider a thin spherical shell characterized…
Using the conventional gravastar model, that is, an object constituted by two components where one of them is a massive infinitely thin shell and the other one is a de Sitter interior spacetime, we physically interpret a solution…
Mazur and Mottola's gravastar model represents one of the few serious alternatives to the traditional understanding of the black hole. The gravastar is typically regarded as a theoretical alternative for the black hole. This article…
In this paper we attempt to construct a regular gravastar model using the UV corrected framework of Loop Quantum Cosmology. We find that a stable gravastar model can be constructed with a number of unique features: (i) no thin shell…
Gravitational waves from compact objects provide information about their structure, probing deep into strong-gravity regions. Here we illustrate how the presence or absence of an event horizon can produce qualitative differences in the…
Gravitational vacuum condensate stars, also known as gravastars, have been proposed as an alternative to black holes. Their interior contains a perfect fluid with an equation of state akin to that of a cosmological constant. For this…
Gravastars, hypothetic astrophysical objects, consisting of a dark energy condensate surrounded by a strongly correlated thin shell of anisotropic matter, have been proposed as an alternative to the standard black hole picture of general…
Any observer outside black holes cannot detect any physical signal produced by the black holes themselves, since, by definition, the black holes are not located in the causal past of the outside observer. In fact, what we regard as black…