Five-Dimensional Traversable Wormholes in Einstein-Gauss-Bonnet Gravity with a Cloud of Strings

Abstract

We present an exact static and spherically symmetric traversable wormhole solution in 5D Einstein-Gauss-Bonnet (EGB) gravity supported by a Letelier cloud of strings. The physically admissible parameter space is determined by imposing the flare-out condition together with the positivity of the string-cloud density, and the resulting spacetime is shown to be asymptotically flat. An analysis of the Ricci scalar, Ricci tensor squared, and Kretschmann scalar confirms that the geometry is free from curvature singularities. The effective null, weak, strong and dominant energy conditions are either satisfied or saturated at the throat. The generalized TOV equation demonstrates that the wormhole remains in mechanical equilibrium. We further investigate its traversability by studying the proper radial distance, embedding diagrams, traversal time, proper acceleration, and tidal accelerations, showing that the solution satisfies the Morris-Thorne criteria for traversable wormholes. The optical properties of the spacetime are explored through null geodesics, unstable photon circular orbits, and the corresponding shadow, revealing the influence of both the Gauss-Bonnet coupling and the string-cloud density. Finally, scalar perturbations are analyzed using the sixth-order WKB approximation method together with time-domain evolution. The quasinormal mode spectra exhibit negative imaginary frequencies throughout the considered parameter space, indicating linear stability, while the close agreement between the WKB, time-domain, and eikonal results provides additional consistency for the analysis. These results demonstrate that higher-curvature effects in 5D EGB gravity can support a regular, traversable and dynamically stable wormhole sustained by a physically motivated string-cloud matter source.

29 pages, 17 figures