Models of Anisotropic Self-Gravitating Source in Einstein-Gauss-Bonnet Gravity

TL;DR

This paper investigates the dynamics of anisotropic fluid collapse and expansion in 5D Einstein-Gauss-Bonnet gravity, deriving solutions that depend on arbitrary functions and analyzing their physical viability and effects of the Gauss-Bonnet coupling.

Contribution

It introduces new anisotropic solutions in 5D Einstein-Gauss-Bonnet gravity using auxiliary functions, exploring collapse and expansion scenarios with physical validity.

Findings

Solutions describe both collapse and expansion depending on initial data.

Energy conditions are satisfied for specific parameter values.

Gauss-Bonnet coupling influences the dynamics of the gravitational source.

Abstract

In this paper, we have studied gravitational collapse and expansion of non-static anisotropic fluid in $5D$ Einstein Gauss-Bonnet gravity. For this purpose, the field equations have been modeled and evaluated for the given source and geometry. The two metric functions have been expressed in terms of parametric form of third metric function. We have examined the range of parameter $\beta$ (appearing in the form of metric functions) for which $\Theta$ the expansion scalar becomes positive/negative leads to expansion/collapse of the source. The trapped surface condition has been explored by using definition of Misner-Sharp mass and auxiliary solutions. The auxiliary solutions of the field equations involve a single function which generates two types of anisotropic solutions. Each solution can be represented in term of arbitrary function of time, this function has been chosen arbitrarily to fit the different astrophysical time profiles. The existing solutions forecast gravitational expansion and collapse depending on the choice of initial data. In this case, it has been investigated wall to wall collapse of spherical source. The dynamics of the spherical source has been observed graphically with the effects of Gauss-Bonnet coupling term $\alpha$ in the case of collapse and expansion. The energy conditions are satisfied for the specific values of parameters in the both solutions, this implies that the solutions are physically acceptable.