Related papers: Gravastars must have anisotropic pressures
The properties of a star with constant positive energy density inside (as for the Schwarzschild interior geometry) and a negative pressure are investigated, using a static conformally flat spacetime. Because of the negative pressure, the…
We illustrate that regular black holes and horizonless stars, typically considered as quite distinct families of black hole mimickers, are intimately intertwined. We show that any spherically symmetric regular black hole can be continuously…
This study analyzes the physical features of a gravastar within the $f(\mathcal{Q}, \mathbb{T})$ gravity framework, where $\mathcal{Q}$ is the non-metricity scalar and $\mathbb{T}$ is the trace of the energy-momentum tensor. Gravastars…
In this paper we investigate the gravitational vacuum stars which called gravastars in the non-minimally coupled models with electromagnetic and gravitational fields. We consider two non-minimal models and find the corresponding spherically…
A new model is proposed to a collapsing star consisting of an anisotropic fluid with bulk viscosity, radial heat flow and outgoing radiation. In a previous paper one of us has introduced a function time dependent into the $g_{rr}$, besides…
A new final state of gravitational collapse is proposed. By extending the concept of Bose-Einstein condensation to gravitational systems, a cold, dark, compact object with an interior de Sitter condensate $p_{_V} = -\rho_{_V}$ and an…
We consider a spherically symmetric black hole in equilibrium with surrounding classical matter that is characterized by a nonlinear dependence of the radial pressure p_{r} on the density {\rho}. We examine under which requirements such an…
We investigate here the spectrum of gravitational collapse endstates when arbitrarily small perfect fluid pressures are introduced in the classic black hole formation scenario as described by Oppenheimer, Snyder and Datt (OSD) [1]. This…
We consider a way to avoid black hole singularities by gluing a black hole exterior to an interior with a tube-like geometry consisting of a direct product of two-dimensional AdS, dS, or Rindler spacetime with a two-sphere of constant…
This paper examines the structure of a gravitationally vacuum star (also known as gravastar) in the background of ${f}(\Re,\mathcal{T}^{2})$ theory. This hypothetical object can be treated as a substitute of a black hole, with three…
Even when we consider Newtonian stars, i.e., stars with surface gravitational redshift, z<< 1, it is well known that, theoretically, it is possible to have stars, supported against self-gravity, almost entirely by radiation pressure.…
We argue that an arbitrary general relativistic static anisotropic fluid sphere, (static and spherically symmetric but with transverse pressure not equal to radial pressure), can nevertheless be successfully mimicked by suitable linear…
We study generalizations of Buchdahl's compactness limits for perfect-fluid star solutions of $D$-dimensional Einstein gravity coupled to higher-curvature corrections. We focus on Quasi-topological theories involving infinite towers of…
We study self-gravitating stars in the bootstrapped Newtonian picture for polytropic equations of state. We consider stars that span a wide range of compactness values. Both matter density and pressure are sources of the gravitational…
We explore gravitating relativistic spheres composed of an anisotropic, barotropic uid. We assume a bi-polytropic equation of state which has a linear and a power-law terms. The generalized Tolman-Oppenheimer-Volkoff (TOV) equation which…
An anisotropic fluid with a negative radial pressure $p = - \rho$ is supposed to exist near the horizon of a Schwarzschild black hole. The constant energy density $\rho$ depends only on the black hole mass. The radial acceleration of the…
We explore the classical stability of topological black holes in d-dimensional anti-de Sitter spacetime, where the horizon is an Einstein manifold of negative curvature. According to the gauge invariant formalism of Ishibashi and Kodama,…
We consider a toy model for relativistic collapse of an homogeneous perfect fluid that takes into account an equation of state for high density matter, in the form of an Hagedorn phase, and semiclassical corrections in the strong field. We…
This paper discusses the configuration of gravitational vacuum star or gravastar with the impact of geometry and matter coupling present in $f(R,T)$ gravity. The gravastar is also conceptualized as a substitute for a black hole which is…
We study equilibrium configurations of a homogenous ball of matter in a bootstrapped description of gravity which includes a gravitational self-interaction term beyond the Newtonian coupling. Both matter density and pressure are accounted…