Wormhole solutions with a polynomial equation-of-state and minimal violation of the null energy condition

F Parsaei,S Rastgoo

doi:10.1140/epjc/s10052-020-7932-8

F Parsaei, S Rastgoo

Open Access

https://doi.org/10.1140/epjc/s10052-020-7932-8

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Abstract

This paper discusses wormholes supported by general equation-of-state , resulting in a significant combination of the linear equation-of-state and some other models. Wormhole with a quadratic equation-of-state is studied as a particular example. It is shown that the violation of null energy condition is restricted to some regions in the vicinity of the throat. The combination of barotropic and polytropic equation-of-state has been studied. We consider fluid near the wormhole throat in an exotic regime which at some r=r_{1}, the exotic regime is connected to a distribution of asymptotically dark energy regime with -1<omega <-1/3. We have presented wormhole solutions with small amount of exotic matter. We have shown that using different forms of equation-of-state has a considerable effect on the minimizing violation of the null energy condition. The effect of many parameters such as redshift as detected by a distant observer and energy density at the throat on the r_1 is investigated. The solutions are asymptotically flat and compatible with presently available observational data at the large cosmic scale.

Highlights

Application of quantum inequalities imposed a bound on exotic energy densities [35]
Wormholes have attracted a lot of attention in the literature and a large number of models have been proposed in this realm. Many of these studies are presented to answer to the basic question, how to avoid or at least minimize the requirement of the exotic Null energy condition (NEC) violating matter? Minimizing the usage of exotic matter for the physical viability of wormhole has received considerable attention
We have shown the fact that the choice of EoS for the description of matter presenting the wormhole has great relevance in the violation of the NEC in the wormhole static solutions

Summary

Introduction

Application of quantum inequalities imposed a bound on exotic energy densities [35]. The quantum effects allow local violation of energy conditions, but this bound implies that any inertial observer in flat spacetime cannot see an arbitrarily large negative energy density which lasts for an arbitrarily long period of time [36]. The exotic nature of phantom energy leads to some unusual cosmological consequences such as big rip, phantom fluid is a good candidate to support wormhole solutions It violates the NEC and is speculated to be a possible driving late time cosmic acceleration. Azreg-Aïnou by considering two barotropic equations of state for lateral and radial pressures has presented wormholes with no gluing effects [65] In another method, Remo and Lobo have proposed solutions in which phantom fluid is concentrated in the neighborhood of the throat to ensure the flaring out condition [66]. Discussions and Concluding remarks are presented in the last section

The general model of wormhole theory

Wormhole with a quadratic equation of state

Combination of barotropic and polytropic equation of state

Discussion and concluding remarks