Stable Thin-shell Wormholes Research Articles

Extremal surfaces and thin-shell wormholes

We study extremal surfaces in a traversable wormhole geometry that connects two locally ${\mathrm{AdS}}_{5}$ asymptotic regions. In the context of the $\mathrm{AdS}/\mathrm{CFT}$ correspondence, we use these to compute the holographic entanglement entropy for different configurations: First, we consider an extremal surface anchored at the boundary on a spatial 2-sphere of radius $R$. The other scenario is a slab configuration which extends in two of the boundary spacelike directions while having a finite size $L$ in the third one. We show that in both cases the divergent and the finite pieces of the holographic entanglement entropy give results consistent with the holographic picture and this is used to explore the phase transitions that the dual theory undergoes. The geometries we consider here are stable thin-shell wormholes with flat codimension-one hypersurfaces at fixed radial coordinate. They appear as electrovacuum solutions of higher-curvature gravity theories coupled to Abelian gauge fields. The presence of the thin shells produces a refraction of the extremal surfaces in the bulk, leading to the presence of cusps in the phase space diagram. Further, the traversable wormhole captures a phase transition for the subsystems made up of a union of disconnected regions in different boundaries. We discuss these and other features of the phase diagram.

Thin-Shell Wormholes in Einstein and Einstein–Gauss–Bonnet Theories of Gravity

We review recent works on the possibility for eternal existence of thin-shell wormholes on Einstein and Einstein–Gauss–Bonnet gravity. We introduce thin-shell wormholes that are categorized into a class of traversable wormhole solutions. After that, we discuss stable thin-shell wormholes with negative-tension branes in Reissner–Nordström–(anti) de Sitter spacetimes in d-dimensional Einstein gravity. Imposing Z2 symmetry, we construct and classify traversable static thin-shell wormholes in spherical, planar and hyperbolic symmetries. It is found that the spherical wormholes are stable against spherically symmetric perturbations. It is also found that some classes of wormholes in planar and hyperbolic symmetries with a negative cosmological constant are stable against perturbations preserving symmetries. In most cases, stable wormholes are found with the appropriate combination of an electric charge and a negative cosmological constant. However, as special cases, there are stable wormholes even with a vanishing cosmological constant in spherical symmetry and with a vanishing electric charge in hyperbolic symmetry. Subsequently, the existence and dynamical stability of traversable thin-shell wormholes with electrically neutral negative-tension branes is discussed in Einstein–Gauss–Bonnet theory of gravitation. We consider radial perturbations against the shell for the solutions, which have the Z2 symmetry. The effect of the Gauss–Bonnet term on the stability depends on the spacetime symmetry.

Thin-shell wormholes in AdS5 and string dioptrics

We consider string probes in a traversable wormhole geometry that connects two locally AdS5 asymptotic regions. Holographically, this describes two interacting copies of a 4-dimensional gauge theory. We consider string configurations whose endpoints are located either in the same boundary or in the two different boundaries of the wormhole. A string with both endpoints in the same boundary is dual to a quark-antiquark pair charged under the same gauge field, while a string extending through the wormhole describes a pair of colored particles charged under two different gauge fields. When one considers a quark-antiquark pair in each boundary, the system undergoes a phase transition: while for small separation each pair of charges exhibits Coulomb interaction, for large separation the charges in different field theories pair up. This behavior had previously been observed in other geometric realizations such as locally AdS5 wormhole solutions with hyperbolic throats. The geometries we consider here, in contrast, are stable thin-shell wormholes with flat codimension-one hypersurfaces at fixed radial coordinate. They appear as electrovacuum solutions of higher-curvature gravity theories coupled to Abelian gauge fields. The presence of the thin-shells produces a refraction of the string configurations in the bulk, leading to the presence of cusps in the phase space diagram. We discuss these and other features of the phase diagram, including the analogies and difference with other wormhole solutions considered in related contexts.

A note on thin-shell wormholes with charge in F(R)-gravity

In their recent work (Eiroa and Aguirre in Eur Phys J C 76:132, 2016), Eiroa and Aguirre introduced thin-shell wormholes in Fleft( Rright) =R+alpha R^{2}-gravity coupled with the Maxwell electromagnetic field. Here in this note we shall address an interesting feature of their results which has been missed. It will be shown that thin-shell wormhole can not be formed in the black hole spacetime solution of this theory but instead there are rooms for making stable thin-shell wormholes in non-black hole bulk spacetime as was noted in Eiroa and Aguirre (2016). This study is not a comment on very correct results of Eiroa and Aguirre (2016) but instead it is a complementary result to their paper.

Thin-shell wormholes constrained by cosmological observations

We investigate the thin-shell wormholes constrained by cosmological observations for the first time in the literature. Without loss of generality, we study the thin-shell wormholes in $\omega$CDM model and analyze their stability under perturbations preserving the symmetry. Firstly, we constrain the $\omega$CDM model using a combination of Union 2.1 SNe Ia data, the latest $H(z)$ data and CMB data. Secondly, we use the constrained dark energy equation of state (EoS) $\omega$ which lies in $[-1.05,-0.89]$ to investigate thin-shell wormholes of various black hole spacetimes. We find that the stable Schwarzschild and Reinssner-Nordstr\"{o}m thin-shell wormholes constrained by cosmological observations do not exist. In addition, the method we developed can be applied into exploring the stable thin-shell wormholes from any black hole spacetime in the framework of any cosmological theory.

Construction of thin shell wormholes from metric f(R) gravity

In this paper, we have constructed spherically symmetric thin-shell wormholes (WHs) by surgically grafting two geometries of charged black hole in the framework of f(R) higher curvature invariants (threaded by exotic matter). We have investigated the stable/unstable regimes for couple of f(R) models using the potential approach formulated by Eiroa with radial perturbation. We have categorized our analysis for different values of charge as well as the parameters involved in the particular mode of f(R) gravity. We have found both stable and unstable regions using modified Chaplygin gas in this scenario and the results are shown through plots. We found that there exists a parametric space for equation of state and quadratic as well as cubic gravities in which one can accommodate more stable thin-shell WHs.

Negative tension branes as stable thin shell wormholes

We investigate negative tension branes as stable thin shell wormholes (TSWs) in Reissner–Nordström-(anti) de Sitter spacetimes in d dimensional Einstein gravity. Imposing Z2 symmetry, we construct and classify traversable static TSWs in spherical, planar (or cylindrical) and hyperbolic symmetries. In spherical geometry, we find the higher dimensional counterpart of Barceló and Visser’s wormholes, which are stable against spherically symmetric perturbations. We also find the classes of TSWs in planar and hyperbolic symmetries with a negative cosmological constant, which are stable against perturbations preserving symmetries. In most cases, stable wormholes are found with the combination of an electric charge and a negative cosmological constant. However, as special cases, we find stable wormholes even with vanishing cosmological constant in spherical symmetry and with vanishing electric charge in hyperbolic symmetry.

D-Dimensional non-asymptotically flat thin-shell wormholes in Einstein–Yang–Mills-dilaton gravity

Thin-shell wormholes in Einstein–Yang–Mills-dilaton (EYMD) gravity are considered. We show that a non-asymptotically flat (NAF) black hole solution of the d-dimensional EYMD theory provides stable thin-shell wormholes which are supported entirely by exotic matter. The presence of dilaton makes the spacetime naturally NAF, and with our conclusion it remains still open to construct wormholes supported by normal matter between two such spacetimes.