Stability of ABG thin-shell around a traversable wormhole

2021 ◽  
pp. 2150044
Author(s):  
M. Sharif ◽  
Komal Ashraf
Keyword(s):  
Thin Shell ◽  
Shape Function ◽  
Energy Conditions ◽  
Energy Tensor ◽  
De Sitter ◽  
Stress Energy Tensor ◽  
Regular Black Hole ◽  
Traversable Wormhole ◽  
Stress Energy ◽  
Barotropic Equation

This paper investigates stability of thin-shell developed from the matching of interior traversable wormhole with exterior Ayon–Beato–Garcia–de Sitter regular black hole through cut and paste approach. We employ Israel formalism and Lanczos equations to obtain the components of surface stress-energy tensor at thin-shell. These surface stresses violate null and weak energy conditions that suggest the presence of exotic matter at thin-shell. The surface pressure explains collapse as well as expanding behavior of the developed geometry. We explore stability of the constructed thin-shell through both perturbations along shell radius as well as barotropic equation of state for three appropriate values of the shape function [Formula: see text]. It is concluded that stability of thin-shell depends on the shape function, charge and cosmological constant.

scholarly journals Stability of the Regular Hayward Thin-Shell Wormholes

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
M. Sharif ◽  
Saadia Mumtaz
Keyword(s):  
Black Hole ◽  
Thin Shell ◽  
Energy Conditions ◽  
Stability Conditions ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Cosmic Expansion ◽  
Stress Energy ◽  
Thin Shell Wormholes ◽  
The Stability

The aim of this paper is to construct regular Hayward thin-shell wormholes and analyze their stability. We adopt Israel formalism to calculate surface stresses of the shell and check the null and weak energy conditions for the constructed wormholes. It is found that the stress-energy tensor components violate the null and weak energy conditions leading to the presence of exotic matter at the throat. We analyze the attractive and repulsive characteristics of wormholes corresponding toar>0andar<0, respectively. We also explore stability conditions for the existence of traversable thin-shell wormholes with arbitrarily small amount of fluid describing cosmic expansion. We find that the space-time has nonphysical regions which give rise to event horizon for0<a0<2.8and the wormhole becomes nontraversable producing a black hole. The nonphysical region in the wormhole configuration decreases gradually and vanishes for the Hayward parameterl=0.9. It is concluded that the Hayward and Van der Waals quintessence parameters increase the stability of thin-shell wormholes.

scholarly journals Schwarzschild-de Sitter and Anti-de Sitter Thin-Shell Wormholes and Their Stability

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
M. Sharif ◽  
Saadia Mumtaz
Keyword(s):  
Thin Shell ◽  
Chaplygin Gas ◽  
Exotic Matter ◽  
Energy Conditions ◽  
Energy Tensor ◽  
De Sitter ◽  
Stress Energy ◽  
Linear Perturbations ◽  
Unstable Solutions ◽  
Thin Shell Wormholes

This paper is devoted to construct Schwarzschild-de Sitter and anti-de Sitter thin-shell wormholes by employing Visser’s cut and paste technique. The Darmois-Israel formalism is adopted to formulate the surface stresses of the shell. We analyze null and weak energy conditions as well as attractive and repulsive characteristics of thin-shell wormholes. We also explore stable and unstable solutions against linear perturbations by taking two different Chaplygin gas models for exotic matter. It is concluded that the stress-energy tensor components violate the null and weak energy conditions indicating the existence of exotic matter at the wormhole throat. Finally, we find unstable and stable configurations for the constructed thin-shell wormholes.

scholarly journals Energy condition in unimodular f(R, T) gravity

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
Fateme Rajabi ◽  
Kourosh Nozari
Keyword(s):  
Power Law ◽  
Energy Condition ◽  
Energy Conditions ◽  
Energy Tensor ◽  
De Sitter ◽  
Stress Energy Tensor ◽  
Modified Gravity Theory ◽  
Stress Energy ◽  
The Stability ◽  
Interesting Alternative

AbstractWe study an interesting alternative of modified gravity theory, namely, the unimodular f(R, T) gravity in which R is the Ricci scalar and T is the trace of the stress–energy tensor. We study the viability of the model by using the energy conditions. We discuss the strong, weak, null and dominant energy conditions in terms of deceleration, jerk and snap parameters. We investigate energy conditions for reconstructed unimodular f(R, T) models and give some constraints on the parametric space of the model. We observe that by setting appropriately free parameters, energy conditions can be satisfied. Furthermore, we study the stability of the solutions in perturbations framework. In this case, we investigate stability conditions for de Sitter and power law solutions and we examine viability of cosmological evolution of these perturbations. The results show that for some values of the input parameters, for which energy conditions are satisfied, de Sitter and power-law solutions may be stable.

Renormalized quantum stress–energy tensor for massive spinor fields around global monopoles

2020 ◽  
Vol 35 (11) ◽  
pp. 2050077
Author(s):  
Owen Pavel Fernández Piedra
Keyword(s):  
Spinor Field ◽  
Energy Conditions ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Spinor Fields ◽  
Characteristic Radius ◽  
Stress Energy ◽  
Massive Spinor ◽  
Global Monopoles ◽  
Tensor Formula

The renormalized quantum stress–energy tensor [Formula: see text] for a massive spinor field around global monopoles is constructed within the framework of Schwinger–DeWitt approximation, valid whenever the Compton length of the quantum field is much less than the characteristic radius of the curvature of the background geometry. The results obtained show that the quantum massive spinor field in the global monopole spacetime violates all the pointwise energy conditions.

On several static cylindrically symmetric solutions of the Einstein equations

2016 ◽  
Vol 31 (11) ◽  
pp. 1650068
Author(s):  
Sergey Grigoryev ◽  
Arkadiy Leonov
Keyword(s):  
Einstein Equations ◽  
Massless Scalar ◽  
Energy Tensor ◽  
Massless Scalar Field ◽  
Stress Energy Tensor ◽  
Perfect Fluid Solution ◽  
Cylindrically Symmetric ◽  
Special Cases ◽  
Stress Energy ◽  
Barotropic Equation

We study the Einstein equations in the static cylindrically symmetric case with the stress–energy tensor of the form [Formula: see text], where [Formula: see text] is an unknown function and [Formula: see text], [Formula: see text], [Formula: see text] are arbitrary real constants ([Formula: see text] is assumed to be nonzero). The stress–energy tensor of this form includes as special cases several well-known solutions, such as the perfect fluid solution with the barotropic equation of state, the solution with the static electric field and the solution with the massless scalar field. We solve the Einstein equations with this stress–energy tensor and study some properties of the obtained metric.

scholarly journals Constructions of f(R,G,𝒯) gravity from some expansions of the Universe

2020 ◽  
Vol 35 (31) ◽  
pp. 2050203
Author(s):  
Ujjal Debnath
Keyword(s):  
Energy Conditions ◽  
Energy Tensor ◽  
De Sitter ◽  
Field Equations ◽  
Least Action Principle ◽  
Future Singularity ◽  
Least Action ◽  
The Least Action Principle ◽  
Modified Gravity Theory ◽  
Stress Energy

Here we propose the extended modified gravity theory named [Formula: see text] gravity where [Formula: see text] is the Ricci scalar, [Formula: see text] is the Gauss–Bonnet invariant, and [Formula: see text] is the trace of the stress-energy tensor. We derive the gravitational field equations in [Formula: see text] gravity by taking the least action principle. Next we construct the [Formula: see text] in terms of [Formula: see text], [Formula: see text] and [Formula: see text] in de Sitter as well as power-law expansion. We also construct [Formula: see text] if the expansion follows the finite-time future singularity (big rip singularity). We investigate the energy conditions in this modified theory of gravity and examine the validity of all energy conditions.

scholarly journals On a viable first-order formulation of relativistic viscous fluids and its applications to cosmology

2017 ◽  
Vol 26 (13) ◽  
pp. 1750146 ◽  
Author(s):  
Marcelo M. Disconzi ◽  
Thomas W. Kephart ◽  
Robert J. Scherrer
Keyword(s):  
Equations Of Motion ◽  
Heavy Ion ◽  
Viscous Fluids ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Relativistic Fluids ◽  
First Order ◽  
Ion Collisions ◽  
Stress Energy ◽  
Barotropic Equation

We consider a first-order formulation of relativistic fluids with bulk viscosity based on a stress-energy tensor introduced by Lichnerowicz. Choosing a barotropic equation-of-state, we show that this theory satisfies basic physical requirements and, under the further assumption of vanishing vorticity, that the equations of motion are causal, both in the case of a fixed background and when the equations are coupled to Einstein's equations. Furthermore, Lichnerowicz's proposal does not fit into the general framework of first-order theories studied by Hiscock and Lindblom, and hence their instability results do not apply. These conclusions apply to the full-fledged nonlinear theory, without any equilibrium or near equilibrium assumptions. Similarities and differences between the approach explored here and other theories of relativistic viscosity, including the Mueller–Israel–Stewart formulation, are addressed. Cosmological models based on the Lichnerowicz stress-energy tensor are studied. As the topic of (relativistic) viscous fluids is also of interest outside the general relativity and cosmology communities, such as, for instance, in applications involving heavy-ion collisions, we make our presentation largely self-contained.

Dark ingredients in one drop

Open Physics ◽  
2011 ◽  
Vol 9 (3) ◽  
Author(s):  
Irina Dymnikova ◽  
Evgeny Galaktionov
Keyword(s):  
Cosmological Term ◽  
Energy Tensor ◽  
De Sitter ◽  
Stress Energy Tensor ◽  
Dark Fluid ◽  
Spatially Inhomogeneous ◽  
Stress Energy ◽  
Gravitational Vacuum ◽  
De Sitter Vacuum ◽  
Unified Description

AbstractA unified description of dark ingredients is realized by a vacuum dark fluid defined by symmetry of its stress-energy tensor and allowed by General Relativity. The symmetry is reduced compared with the maximally symmetric de Sitter vacuum, which makes vacuum dark fluid essentially anisotropic and allows its density and pressure to evolve. It represents distributed vacuum dark energy by a time-evolving and spatially inhomogeneous cosmological term, and vacuum dark matter by gravitational vacuum solitons which are regular gravitationally bound structures without horizons (dark particles or dark stars), with the de Sitter centre (Λδki) in de Sitter space (λδki).

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