Flat Wormhole Solutions Research Articles

Traversable wormholes satisfying energy conditions in f(Q) gravity

In this article, a new family of asymptotically flat wormhole solutions in the context of symmetric teleparallel gravity, i.e., f(Q) theory of gravity, are presented. Considering a power-law shape function and some different forms of the f(Q) function, we show that a wide variety of wormhole solutions for which the matter fields satisfy some energy conditions, are accessible. We realize that the presence of f(Q) gravity will be enough to sustain a traversable wormhole without exotic matter. The influence of the free parameters of the shape function and the f(Q) models on the energy conditions is investigated. The equation of state and the boundary conditions are analyzed.

Dymnikova-Schwinger traversable wormholes

In this paper, we obtain new d-dimensional and asymptotically flat wormhole solutions by assuming a specific form of the energy density distribution. This is addressed by considering the generalization of the so-called Dymnikova model, originally studied in the context of regular black holes. In this way, we find constraints for the involved parameters, namely, the throat radius, the scale associated to the matter distribution, and the spacetime dimension, to build those wormholes. Following, we study the properties of the obtained solutions, namely, embedding diagrams as well as Weak and Null Energy Conditions (WEC and NEC). We show that the larger the dimension, the larger the flatness of the wormhole and the more pronounced the violation of these energy conditions. We also show that the corresponding fluid behaves as phantom-like for d ≥ 4 in the neighborhood of the wormhole throat. In addition, we specialize the employed model for d = 4 spacetime, associating it with the gravitational analog of the Schwinger effect in a vacuum and correcting the model by introducing a minimal length via Generalized Uncertainty Principle (GUP). Thus, we obtain a novel traversable and asymptotically flat wormhole solution by considering that the minimal length is very tiny. The associated embedding diagram shows us that the presence of this fundamental quantity increases the slope of the wormhole towards its throat compared with the case without it. That correction also attenuates the WEC (and NEC) violations nearby the throat, with the fluid ceasing to be a phantom-type at the Planck scale, unlike the case without the minimal length.

Wormhole in f(Q) gravity

In this paper, exact asymptotically flat wormhole solutions in the context of symmetric teleparallel gravity, i.e., $f(Q)$ theory of gravity, are investigated. Since modified theories of gravity provide new field equations, we have analyzed some possible wormhole solutions by using modified field equations. Four different forms of the $f(Q)$ function are considered then the shape function is calculated with some different equations of state. Also we have used a power-law shape function with these models, which lead to an asymptotically barotropic equation of state. Some physical and mathematical properties of the solutions, like energy conditions and boundary conditions, are addressed .

From black holes to baby universes in CGHS gravity

We study hat{mathrm{CGHS}} gravity, a variant of the matterless Callan-Giddings-Harvey-Strominger model. We show that it describes a universal sector of the near horizon perturbations of non-extremal black holes in higher dimensions. In many respects this theory can be viewed as a flat space analog of Jackiw-Teitelboim gravity. The result for the Euclidean path integral implies that hat{mathrm{CGHS}} is dual to a Gaussian ensemble that we describe in detail. The simplicity of this theory allows us to compute exact quantities such as the quenched free energy and provides a useful playground to study baby universes, averages and factorization. In particular we derive a “wormhole = diagonal” identity. We also give evidence for the existence of a non-perturbative completion in terms of a matrix model. Finally, flat wormhole solutions in this model are discussed.

Wormhole structures in logarithmic-corrected R^2 gravity

This paper is devoted to find the feasible shape functions for the construction of static wormhole geometry in the frame work of logarithmic-corrected R^2 gravity model. We discuss the asymptotically flat wormhole solutions sustained by the matter sources with anisotropic pressure, isotropic pressure and barotropic pressure. For anisotropic case, we consider three shape functions and evaluate the null energy conditions and weak energy conditions graphically along with their regions. Moreover, for barotropic and isotropic pressures, we find shape function analytically and discuss its properties. For the formation of traversable wormhole geometries, we cautiously choose the values of parameters involved in f(R) gravity model. We show explicitly that our wormhole solutions violate the non-existence theorem even with logarithmic corrections. We discuss all physical properties via graphical analysis and it is concluded that the wormhole solutions with relativistic formalism can be well justified with logarithmic corrections.

Traversable wormholes supported by GUP corrected Casimir energy

In this paper, we investigate the effect of the Generalized Uncertainty Principle (GUP) in the Casimir wormhole spacetime recently proposed by Garattini (Eur Phys J C 79: 951, 2019). In particular, we consider three types of GUP relations, firstly the Kempf, Mangano and Mann (KMM) model, secondly the Detournay, Gabriel and Spindel (DGS) model, and finally the so-called type II model for the GUP principle. To this end, we consider three specific models of the redshift function along with two different equations of state (EoS), given by {mathcal {P}}_r(r)=omega _r(r) rho (r) and {mathcal {P}}_t(r)=omega _t (r){mathcal {P}}_r(r) and obtain a class of asymptotically flat wormhole solutions supported by Casimir energy under the effect of GUP. Furthermore we check the null, weak, and strong condition at the wormhole throat with a radius r_0, and we show that in general the classical energy conditions are violated by some arbitrary quantity at the wormhole throat. Importantly, we examine the wormhole geometry with semiclassical corrections via embedding diagrams. We also consider the ADM mass of the wormhole, the volume-integral quantifier to calculate the amount of the exotic matter near the wormhole throat, and the deflection angle of light.

Phantom wormhole solutions in a generic cosmological constant background

There are a number of reasons to study wormholes with generic cosmological constant Λ. Recent observations indicate that the present accelerating expansion of the universe demands Λ > 0. On the other hand, some extended theories of gravitation, such as supergravity and superstring theories, possess vacuum states with Λ < 0. Even within the framework of general relativity, a negative cosmological constant permits black holes with horizons topologically different from the usual spherical ones. These solutions are convertible to wormhole solutions by adding some exotic matter. In this paper, the asymptotically flat wormhole solutions in a generic cosmological constant background are studied. By constructing a specific class of shape functions, a mass function, energy density, and pressure profile that support such a geometry are obtained. It is shown that for having such a geometry, the wormhole throat, r0, the cosmological constant, Λ, and the equation of state parameter, ω, should satisfy two specific conditions. The possibility of setting different values for the parameters of the model helps us to find exact solutions for the metric functions, mass functions, and energy–momentum profiles. At last, the volume integral quantifier, which provides useful information about the total amount of energy-condition violating matter, is discussed briefly.

New asymptotically flat phantom wormhole solutions

A possible cause of the late-time cosmic acceleration is an exotic fluid with an equation of state lying within the phantom regime, i.e., $w=p/\ensuremath{\rho}<\ensuremath{-}1$. This violates the null energy condition, which is a fundamental ingredient in wormhole physics. Thus, cosmic phantom energy may, in principle, provide a natural fluid to support wormholes. In this work, we find new asymptotically flat wormhole solutions supported by the phantom energy equation of state, consequently extending previous solutions. Thus, there is no need to surgically paste the interior wormhole geometry to an exterior vacuum spacetime. In the first example, we carefully construct a specific shape function, where the energy density and pressures vanish at large distances as $\ensuremath{\sim}1/{r}^{n}$, with $n>0$. We also consider the ``volume integral quantifier,'' which provides useful information regarding the total amount of energy-condition-violating matter, and show that, in principle, it is possible to construct asymptotically flat wormhole solutions with an arbitrary small amount of energy-condition-violating matter. In the second example, we analyze two equations of state, i.e., ${p}_{r}={p}_{r}(\ensuremath{\rho})$ and ${p}_{t}={p}_{t}(\ensuremath{\rho})$, where we consider a specific integrability condition in order to obtain exact asymptotically flat wormhole solutions. In the final example, we postulate a smooth energy density profile, possessing a maximum at the throat and vanishing at spatial infinity.

Traversable wormhole in the deformed Hořava-Lifshitz gravity

Asymptotically flat wormhole solutions are found in the deformed Ho\v{r}ava-Lifshitz gravity. It turns out that higher curvature terms can not play the role of exotic matters which are crucial to form a traversable wormhole, and external exotic sources are still needed. In particular, the exotic matter behaves like phantom energy if Kehagias-Sfetsos vacuum is considered outside the wormhole. Interestingly, the spherically symmetric setting makes the matter and the higher curvature contribution satisfy four-dimensional conservation of energy in the covariant form.

New features of extended wormhole solutions in the scalar field gravity theories

This paper reports new interesting features characteristic of wormhole solutions in the scalar field gravity theories. To demonstrate these, using a slightly modified form of the Matos–Núñez algorithm, we obtain an extended class of asymptotically flat wormhole solutions belonging to the Einstein minimally coupled scalar field theory. Generally, solutions in these theories do not represent traversable wormholes due to the occurrence of curvature singularities. However, the Ellis I solution of the Einstein minimally coupled theory, when Wick rotated, yields an Ellis class III solution representing a singularity-free traversable wormhole. We see that Ellis I and III are not essentially independent solutions. The Wick-rotated seed solutions, extended by the algorithm, contain two new parameters a and δ. The effect of the parameter a on the geodesic motion of test particles reveals some remarkable features. By arguing for Sagnac effect in the extended Wick-rotated solution, we find that the parameter a can indeed be interpreted as a rotation parameter of the wormhole. The analysis reported here has wide applicability, for it can be adopted in other scalar field theories, including string theory.