scholarly journals Stable Dyonic Thin-Shell Wormholes in Low-Energy String Theory

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Ali Övgün ◽  
Kimet Jusufi
Keyword(s):  
Electric Charge ◽  
Thin Shell ◽  
Magnetic Charge ◽  
State Parameter ◽  
Stability Domain ◽  
Chaplygin Gas ◽  
Space Time ◽  
Exotic Matter ◽  
The Stability ◽  
Parameter Values

Considerable attention has been devoted to the wormhole physics in the past 30 years by exploring the possibilities of finding traversable wormholes without the need for exotic matter. In particular, the thin-shell wormhole formalism has been widely investigated by exploiting the cut-and-paste technique to merge two space-time regions and to research the stability of these wormholes developed by Visser. This method helps us to minimize the amount of the exotic matter. In this paper, we construct a four-dimensional, spherically symmetric, dyonic thin-shell wormhole with electric charge Q, magnetic charge P, and dilaton charge Σ, in the context of Einstein-Maxwell-dilaton theory. We have applied Darmois-Israel formalism and the cut-and-paste method by joining together two identical space-time solutions. We carry out the dyonic thin-shell wormhole stability analyses by using a linear barotropic gas, Chaplygin gas, and logarithmic gas for the exotic matter. It is shown that, by choosing suitable parameter values as well as equation of state parameter, under specific conditions, we obtain a stable dyonic thin-shell wormhole solution. Finally, we argue that the stability domain of the dyonic thin-shell wormhole can be increased in terms of electric charge, magnetic charge, and dilaton charge.

scholarly journals TRAVERSABLE WORMHOLES IN A STRING CLOUD

2008 ◽  
Vol 17 (08) ◽  
pp. 1179-1196 ◽  
Author(s):  
MARTÍN G. RICHARTE ◽  
CLAUDIO SIMEONE
Keyword(s):  
Thin Shell ◽  
Dimensional Space ◽  
Space Time ◽  
Exotic Matter ◽  
Spherically Symmetric ◽  
Related Model ◽  
Traversable Wormholes ◽  
Dimensional Space Time ◽  
Thin Shell Wormholes ◽  
The Stability

We study spherically symmetric thin shell wormholes in a string cloud background in (3 + 1)-dimensional space–time. The amount of exotic matter required for the construction, the traversability and the stability of such wormholes under radial perturbations are analyzed as functions of the parameters of the model. In addition, in the appendices a nonperturbative approach to the dynamics and a possible extension of the analysis to a related model are briefly discussed.

Dynamics of thin-shell wormholes with different cosmological models

2017 ◽  
Vol 26 (05) ◽  
pp. 1741007 ◽  
Author(s):  
Muhammad Sharif ◽  
Saadia Mumtaz
Keyword(s):  
Equation Of State ◽  
Electric Charge ◽  
General Equation ◽  
Thin Shell ◽  
Cosmological Models ◽  
Exotic Matter ◽  
Linear Perturbation ◽  
Stability Regions ◽  
Thin Shell Wormholes ◽  
The Stability

This work is devoted to investigate the stability of thin-shell wormholes in Einstein–Hoffmann–Born–Infeld electrodynamics. We also study the attractive and repulsive characteristics of these configurations. A general equation-of-state is considered in the form of linear perturbation which explores the stability of the respective wormhole solutions. We assume Chaplygin, linear and logarithmic gas models to study exotic matter at thin-shell and evaluate stability regions for different values of the involved parameters. It is concluded that the Hoffmann–Born–Infeld parameter and electric charge enhance the stability regions.

Charged thin-shell wormholes with quintessence effects

2021 ◽  
Vol 36 (26) ◽  
Author(s):  
Saadia Mumtaz
Keyword(s):  
Thin Shell ◽  
Chaplygin Gas ◽  
Exotic Matter ◽  
Stability Regions ◽  
Thin Shell Wormholes ◽  
Theoretical Construction ◽  
The Stability ◽  
Effective Component

This work studies the theoretical construction of charged quintessence thin-shell wormholes using Israel thin-shell approach. The stability of these wormhole solutions is investigated by taking linear, logarithmic and Chaplygin gas models as a constituent of exotic matter at thin-shell. The presence of wormhole stability regions particularly relies on the physically justifiable values of charge and quintessence parameter. It is noted that the increasing value of charge seems as an effective component for stable regions while the rise in negativity of the quintessence parameter gives more stable wormhole configurations.

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.

Thin-shell wormhole from ABGB–de Sitter black holes

2021 ◽  
pp. 2150085
Author(s):  
Nilofar Rahman ◽  
Masum Murshid ◽  
Mehedi Kalam
Keyword(s):  
Black Holes ◽  
Surface Stress ◽  
Thin Shell ◽  
Exotic Matter ◽  
Linear Perturbation ◽  
De Sitter ◽  
Wormhole Solution ◽  
The Stability ◽  
De Sitter Universe ◽  
Charge Formula

A thin shell wormhole is constructed utilizing the cut and paste technique from ABGB–de Sitter black hole derived by Matyjasek et al. The surface stress localized at the wormhole throat is determined using Darmois–Israel formalism. We examine the attractive and repulsive nature of the thin shell wormhole on which cosmological constant [Formula: see text] has a significant effect. For the fixed values of charge [Formula: see text] and mass [Formula: see text], the attractiveness of the wormhole decreases with increasing [Formula: see text]. We calculate the total amount of exotic matter in the shell, which is not much affected by [Formula: see text]. For the construction of the wormhole in de Sitter universe, the regular black holes have to be heavily charged with a light mass to minimize the amount of required exotic matter. The stability of the wormhole solution is explored by considering a general equation of state in the form of linear perturbation. The stability regions are shown in the figures.

A theoretical construction of thin-shell wormhole from regular charged black holes

2020 ◽  
Vol 35 (23) ◽  
pp. 2050136
Author(s):  
Nilofar Rahman ◽  
Masum Murshid ◽  
Farook Rahaman ◽  
Mehedi Kalam
Keyword(s):  
Black Holes ◽  
Equation Of State ◽  
Thin Shell ◽  
Stability Region ◽  
Exotic Matter ◽  
Nonlinear Electrodynamics ◽  
Linear Perturbation ◽  
Charged Black Holes ◽  
Theoretical Construction ◽  
The Stability

We construct a thin-shell wormhole using the cut and paste technique from regular charged black holes with a nonlinear electrodynamics source (proposed by Balart and Vagenas). Using Darmois–Israel formalism we determine the surface stresses, which are localized at the wormhole throat. We also determine the amount of exotic matter present in the shell. To analyze the stability of the constructed wormhole we consider an equation of state as a linear perturbation. The stability region is shown in the graph by varying the values of the parameter.

scholarly journals A reduced-order model for dual state-parameter geostatistical inversion

2020 ◽  
Author(s):  
Yu-Li Wang ◽  
Tian-Chyi Jim Yeh ◽  
Jui-Pin Tsai
Keyword(s):  
State Parameter ◽  
Irregular Domain ◽  
Catchment Scale ◽  
Reduced Order ◽  
Inverse Models ◽  
Order Of Magnitude ◽  
The Stability ◽  
Value Decomposition ◽  
Parameter Values ◽  
Correlated Parameters

Abstract. To properly account the subsurface heterogeneity, geostatistical inverse models usually permit enormous amount of spatial correlated parameters to interpret the collected states. Several reduced-order techniques for the brick domain are investigated to leverage the memory burden of parameter covariance. Their capability to irregular domain is limited. Furthermore, due to the over fitting of states, the estimated parameters usually diverge to unreasonable values. Although some propriate tolerances can be used to eliminate this problem, they are presumed and heavily rely on the personal judgement. To address these two issues, we present a model reduction technique to the irregular domain by singular value decomposition (SVD). Afterward, the state errors and parameters are sequentially updated to leverage the over fitting. The computational advantages of the proposed reduced-order dual state-parameter inverse algorithm are demonstrated through two numerical experiments and one case study in a catchment scale field site. The investigations suggest that the stability of convergence dramatically improves. The estimated parameter values stabilize to reasonable order of magnitude. In addition, the memory requirement significantly reduces while the resolution of estimate preserves. The proposed method benefits multi-discipline scientific problems, especially useful and convenient for assimilating different types of measurements.

scholarly journals New static cylindrical symmetric solutions in GR for unfamiliar EoS parameter values via Noether symmetry

2021 ◽  
Vol 81 (10) ◽  
Author(s):  
Işıl Başaran Öz ◽  
Kazuharu Bamba
Keyword(s):  
Equations Of State ◽  
State Parameter ◽  
Space Time ◽  
Noether Symmetry ◽  
Field Equations ◽  
Eos Parameter ◽  
New Exact Solutions ◽  
Cylindrically Symmetric ◽  
Parameter Values ◽  
Symmetry Method

AbstractThe solutions for the field equations of f(R) gravity are investigated in static cylindrically symmetric space-time. Conserved quantities of the system, as well as unknown functions, can be determined with the help of the Noether symmetry method. In this article, some unknown values of the equations of state parameter (EoS) have emerged as a result of the constraints obtained by analyzing the Noether symmetry equations for the $$f(R)=f_0 R$$ f ( R ) = f 0 R case. Consequently, several new exact solutions have been found for cases of General Relativity in static cylindrically symmetrical space-time for the non-dust matter.

scholarly journals MAGNETIC CHARGE, ANGULAR MOMENTUM AND NEGATIVE COSMOLOGICAL CONSTANT

2003 ◽  
Vol 18 (13) ◽  
pp. 2379-2393 ◽  
Author(s):  
J. J. VAN DER BIJ ◽  
EUGEN RADU
Keyword(s):  
Angular Momentum ◽  
Cosmological Constant ◽  
Electric Charge ◽  
Magnetic Charge ◽  
Flat Space ◽  
Space Time ◽  
Axially Symmetric ◽  
Yang Mills ◽  
Negative Cosmological Constant

We argue that there are no axially symmetric rotating monopole solutions for a Yang–Mills–Higgs theory in flat space–time background. We construct axially symmetric Yang–Mills–Higgs solutions in the presence of a negative cosmological constant, carrying magnetic charge n and a nonvanishing electric charge. However, these solution are also nonrotating.

STABILITY ANALYSIS OF THIN SHELL WORMHOLES SUPPORTED BY THE MODIFIED CHAPLYGIN GAS

2009 ◽  
Vol 18 (13) ◽  
pp. 1977-1990 ◽  
Author(s):  
TANWI BANDYOPADHYAY ◽  
ANUSUA BAVEJA ◽  
SUBENOY CHAKRABORTY
Keyword(s):  
Stability Analysis ◽  
Equation Of State ◽  
Thin Shell ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
De Sitter ◽  
Static Solutions ◽  
Thin Shell Wormholes ◽  
Stable Solutions ◽  
The Stability

In this work, the stability of static solutions of spherical thin shell wormholes is analyzed when a slight perturbation (which preserves the basic symmetry) is applied to them. The modified Chaplygin gas (with α = 1 in the equation of state) has been chosen as a candidate for exotic matter needed around the throat. Different cases for such thin shell wormhole construction have been studied, viz. wormholes constructed from Schwarzschild, Schwarzschild–de Sitter, Schwarzschild–anti-de Sitter and Reissner–Nordström metrics. Depending upon the values of the parameters and some restrictions obeyed by them, static stable solutions are seen to exist in some cases.

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