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This paper explores static spherically symmetric wormhole solutions in the galatic halo region for [Formula: see text] gravity ([Formula: see text] and [Formula: see text] represent the Gauss–Bonnet invariant and trace of the energy–momentum tensor, respectively). We formulate the explicit expressions for matter variables and evaluate wormhole solutions either specifying [Formula: see text] model to construct shape function or taking specific form of the shape function to determine [Formula: see text] model. It is found that null energy condition for the effective energy–momentum tensor is violated throughout the evolution in both cases while physically acceptable wormhole solutions exist only for a considered [Formula: see text] model.

This paper investigates static spherically symmetric traversable wormhole (WH) solutions in [Formula: see text] gravity ([Formula: see text] and [Formula: see text] represent the Gauss–Bonnet invariant and trace of the energy–momentum tensor, respectively). We construct explicit expressions for ordinary matter by taking specific form of redshift function and [Formula: see text] model. To analyze the possible existence of wormholes, we consider anisotropic, isotropic, as well as barotropic matter distributions. The graphical analysis shows the violation of null energy condition for the effective energy–momentum tensor throughout the evolution while ordinary matter meets energy constraints in certain regions for each case of matter distribution. It is concluded that traversable WH solutions are physically acceptable in this theory.

The aim of this paper is to study the dynamical instability of expansion-free spherically symmetric anisotropic fluid in the framework of [Formula: see text] gravity. We apply perturbation scheme of the first-order to the metric functions as well as matter variables and construct modified field equations for both static and perturbed configurations using power-law [Formula: see text] model. To discuss the instability dynamics, we use the contracted Bianchi identities to formulate the dynamical equations in both Newtonian and post-Newtonian regimes. It is found that the range of instability is independent of adiabatic index for expansion-free fluid but depends on anisotropic pressures, energy density and Gauss–Bonnet (GB) terms.

This paper explores the stability of the Einstein universe against linear homogeneous perturbations in the background of [Formula: see text] gravity. We construct static as well as perturbed field equations and investigate stability regions for the specific forms of generic function [Formula: see text] corresponding to conserved as well as nonconserved energy-momentum tensor. We use the equation-of-state parameter to parameterize the stability regions. The graphical analysis shows that the suitable choice of parameters lead to stable regions of the Einstein universe.

This paper investigates inflationary dynamics for isotropic and homogeneous universe model in the background of [Formula: see text] gravity. We construct Hubble-flow functions, slow-roll parameters, amplitude of scalar power spectrum, spectral index and tensor–scalar ratio for a particular form of equation of state which describes quasi-de Sitter expansion. The dynamics of inflationary epoch is analyzed for scalar field as well as fluid cosmology with viable power-law [Formula: see text] model. We obtain different potential functions that correspond to chaotic inflation and Starobinsky type models. The graphical behavior of these parameters shows compatible results with observational Planck 2015 data in this gravity.

This paper is devoted to study the traversable wormhole (WH) solutions in the context of f(𝒢) gravity. For this purpose, we consider the viable power-law form f(𝒢) = a𝒢n as well as specific variable red-shift function and investigate WH geometries for traceless, isotropic as well as barotropic fluids. It is found that in each case, the effective energy-momentum tensor violates the null energy condition throughout the WH throat. We also check the null as well as weak energy conditions for ordinary matter. We conclude that physical acceptable WH solutions exist in certain regions only for radial barotropic case while the range of these regions increases and decreases as the power of 𝒢 increases in even and odd manner, respectively.