Phantom wormhole solutions in a generic cosmological constant background

Abstract

There are a number of reasons to study wormholes with generic cosmological constant Λ. Recent observations indicate that present accelerating expansion of the universe demands Λ > 0. On the other hand, some extended theories of gravitation such as supergravity and superstring theories posses 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, mass function, energy density and pressure profiles which 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 energymomentum profiles. At last, the volume integral quantifier, which provides useful information about the total amount of energy condition violating matter is discussed briefly.

Wormholes and naked singularities in Brans–Dicke cosmology

“…Although the framework of [32] is similar to our and can be obtained via V (φ) = 2Λ, the results of [32] cannot be applied to astrophysics. Wormhole in solutions the GR setting with exotic matter and Λ representing similar behaviour were found in [33,34]. The cosmological constant affects the wormhole and its properties, the wormhole geometry will be dominated by the de Sitter space far from the throat.…”

“…The cosmological constant affects the wormhole and its properties, the wormhole geometry will be dominated by the de Sitter space far from the throat. Our solution is new and differs from the ones of [33,34] since the role of the exotic matter is played by the scalar field.…”

Wormholes in $$R^2$$ R 2 -gravity within the f(R, T) formalism

“…The exact solutions for the matter content of the WH can be obtained by considering a specific form for the shape function [36],…”

Validation of energy conditions in wormhole geometry within viable f(R) gravity

“…Furthermore, the energy density ρ, energy condition terms ρ + p r , ρ + p t , ρ + p r + 2p t , ρ − |p r |, ρ − |p t | and anisotropy parameter are computed. Several authors have studied wormhole modelling by considering power-law shape function [8,11,54,56,[69][70][71]. In this paper, we use b(r) = r r r 0…”