An exact solution of the Einstein field equations given the barotropic equation of state $p=ωρ$ yields two possible models: (1) if $ω<-1$, we obtain the most general possible anisotropic model for wormholes supported by phantom energy and (2) if $ω>0$, we obtain a model for galactic rotation curves. Here the equation of state represents a perfect fluid which may include dark matter. These results illustrate the power and usefulness of exact solutions.
The theoretical construction of a traversable wormhole proposed by Morris and Thorne maintains complete control over the geometry by assigning both the shape and redshift functions, thereby leaving open the determination of the stress-energy tensor. This paper examines the effect of introducing the linear barotropic equation of state $p_r=ωρ$ on the theoretical construction. If either the energy density or the closely related shape function is known, then the Einstein field equations do not ordinarily yield a finite redshift function. If, however, the wormhole admits a one-parameter group of c…
We cut and paste two Banados-Teitelboim-Zanelli (BTZ) spacetimes at a throat by the Darmois-Israel method to construct a rotating wormhole with a thin shell filled with a barotropic fluid. The thin shell at the throat and both sides of the throat corotate. We investigate the linear stability of the thin shell of the rotating wormhole against radial perturbations. We show that the wormhole becomes more and more stable the larger its angular momentum is until the angular momentum reaches a critical value and that the behavior of a condition for stability significantly changes when the angular mo…
The purpose of this paper is to obtain exact solutions of the Einstein field equations describing traversable wormholes supported by phantom energy. Their relationship to exact solutions in the literature is also discussed, as well as the conditions required to determine such solutions.
Formation of specific static wormhole models is discussed, by assuming an $f(\textit{R}, \textit{T}) = R + 2 λT$ extended theory of gravity, $T =- ρ+ P_{r} + 2P_{l}$ being the trace of the energy momentum tensor. In the first part, wormhole solutions are constructed imposing that the radial pressure admits an equation of state corresponding to a varying Chaplygin gas. Two forms for the varying Chaplygin gas are considered, namely $P_{r} = - B b(r)^{u}/ρ^α$ and $P_{r} = -B R(r)^{m}/ ρ^{α}$, respectively. In the second part, the wormhole models are constructed assuming that the radial pressure c…
This paper explores the role of nonlinear electrodynamics on the stable configuration of thin-shell wormholes formulated from two equivalent geometries of Reissner-Nordström black hole with nonlinear electrodynamics. For this purpose, we use cut and paste approach to eliminate the central singularity and event horizons of the black hole geometry. Then, we explore the stability of the developed model by considering different types of matter distribution located at thin-shell, i.e., barotropic model and variable equations of state (phantomlike variable and Chaplygin variable models). We use line…
This paper discusses wormholes supported by general equation-of-state , resulting in a significant combination of the linear equation-of-state and some other models. Wormhole with a quadratic equation-of-state is studied as a particular example. It is shown that the violation of null energy condition is restricted to some regions in the vicinity of the throat. The combination of barotropic and polytropic equation-of-state has been studied. We consider fluid near the wormhole throat in an exotic regime which at some $r=r_{1}$, the exotic regime is connected to a distribution of asymptotically d…
Damghan University（达姆甘大学）；Mangalore Institute of Technology & Engineering（曼格洛尔理工工程学院）；Sri Siddhartha Institute of Technology（斯里西达塔理工大学）；Kuvempu University（库文普大学）；Pacif Institute of Cosmology and Selfology (PICS)（帕西夫宇宙学与自我学研究所（PICS））；Khazar University（哈萨尔大学）；Fukushima University（福岛大学）
Using exactly solvable models, it is shown that black hole singularities in different electrically charged configurations can be cured. Our solutions describe black hole space-times with a wormhole giving structure to the otherwise point-like singularity. We show that geodesic completeness is satisfied despite the existence of curvature divergences at the wormhole throat. In some cases, physical observers can go through the wormhole and in other cases the throat lies at an infinite affine distance.
Friedmann-Robertson-Walker like cosmologies with spherical symmetry
我们重新考虑了金成元[Phys. Rev D 53，6889（1996）]在具有可穿越虫洞的弗里德曼-罗伯逊-沃克宇宙学的背景下讨论的宇宙学模型，其中假设物质内容分为两部分：仅依赖于时间的宇宙部分和仅依赖于空间的虫洞部分。宇宙部分服从正压状态方程$p_c=γρ_c$。完整的分析需要进一步的关注，并揭示了比作者以前所展示的更有趣的结果。它们可以很容易地应用到一大类宇宙学模型的演化，这是更普遍的比FRW模型。
