Modified-gravity wormholes without exotic matter

Abstract

In this paper, we develop an iterative approach to span the whole set of exotic matter models able to drive a traversable wormhole. The method, based on a Taylor expansion of metric and stress-energy tensor components in a neighbourhood of the wormhole throat, reduces the Einstein equation to an infinite set of algebraic conditions, which can be satisfied order by order. The approach easily allows the implementation of further conditions linking the stress-energy tensor components among each other, like symmetry conditions or equations of state. The method is then applied to some relevant examples of exotic matter characterised by a constant energy density and that also show an isotropic behaviour in the stress-energy tensor or obeying to a quintessence-like equation of state.

Spontaneous symmetry breaking in wormholes spacetimes with matter

“…Here, at the bifurcation frequencies ω crl and ω cru the symmetric solutions indeed exhibit a zero mode, which then turns into a second unstable mode in the parameter space where the asymmetric solutions exist. For the asymmetric solutions stability could possibly be achieved by removing the phantom field and modifying gravity instead [35][36][37][38][39][40][41][42][43].…”

Einstein-Gauss-Bonnet traversable wormholes satisfying the weak energy condition

“…It was also found that higher-dimensional cosmological wormholes [9] and wormholes in modified gravity, involving higher order curvature invariants, can satisfy the energy conditions [10][11][12][13][14], at least at the throat. In fact, in modified gravity, it was shown that matter threading the wormhole throat can be imposed to satisfy all of the energy conditions, and it is the higher order curva-ture terms, which may be interpreted as a gravitational fluid, that support these nonstandard wormhole geometries.…”

Thin-shell wormholes with charge in F(R) gravity

“…Static and spherically symmetric black hole solutions in F(R) have been found [35][36][37] in the last decade. Traversable wormholes in F(R) were also studied in recent years [38][39][40][41].…”