On wormhole throats in f (R) gravity theory

Abstract

We study the existence and properties of wormhole throats in modified f (R) gravity theory. Specifically, we concentrate on the cases where the lapse is not necessarily constant, and hence are not limited to the zero tidal force scenarios. In the class of theories whose actions are generated by Lagrangians of the form f (R) = α n R n we find parameters which allow for the existence of energy condition respecting throats, which do not exist in Einstein gravity. We also consider the effect of the modified action on the anisotropy of the models, and find that modified gravity can minimize the amount of anisotropy required to support the existence of a throat. In both these respects, the sector containing theories with positive n is more promising than the negative n sector in comparison to Einstein gravity alone, with large n being most favorable.

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].…”

Nonommutative wormholes in f(R) gravity

“…The basic intent in modifying or extending general relativity was to explain certain cosmic phenomena such as dark matter, cosmic inflation in the early Universe, and the present cosmic accelerated expansion [17]. Furthermore "it is of interest to study gravitational theories which are diffeomorphism invariant and give Einstein gravity in an appropriate limit, but deviate from Einstein gravity in some way outside of the realm where gravitational effects have commonly been observed [19]." Our interest is confined to f (R) gravity, where R is the Ricci scalar.…”

“…It is worth noting that wormholes with power-law F (R) gravity and a non-constant redshift function have been explored in the literature [19], but for simplicity and viability purposes, we shall restrict ourselves to the above assumption. In solving the field equations, we have taken the energy density of the static and spherically symmetric smeared and particle-like gravitational source to be of the form given in Eq.…”

Looking for empty topological wormhole spacetimes in F ( R )-modified gravity

“…the strong energy condition) just choosing in an opportune way the metric components. If this procedure may look quite artificial, then following [8,9] it is possible to show that models as F (R) = n a n R n for suitable integer n display a matter behavior close to the wormhole throat such to respect the energy conditions and to prevent large anisotropies -typical features of Einstein's wormholes. The existence of necessary conditions for having wormholes which respect the weak energy condition and possibly the strong energy condition has been studied in [10] at least in polynomial models of the third order or higher.…”