Five-dimensional compact stars in Einstein-Gauss-Bonnet gravity

TL;DR

This paper explores five-dimensional Einstein-Gauss-Bonnet gravity to model neutron stars, revealing how the Gauss-Bonnet term affects their structure, maximum mass, and compatibility with observational data.

Contribution

It derives hydrostatic equilibrium equations in 5D EGB gravity and analyzes their impact on neutron star properties using realistic equations of state.

Findings

Gauss-Bonnet term causes significant deviations from Einstein gravity.

Higher maximum masses are possible with certain Gauss-Bonnet coupling values.

Causality violations occur at high masses for large coupling values.

Abstract

Within the framework of Einstein-Gauss-Bonnet theory in five-dimensional spacetime ($5D$ EGB), we derive the hydrostatic equilibrium equations and solve them numerically to obtain neutron stars for both isotropic and anisotropic distribution of matter. The mass-radius relations are obtained for SLy equation of state, which describes both the solid crust and the liquid core of neutron stars, and for a wide range of the Gauss-Bonnet coupling parameter $\alpha$. More specifically, we find that the contribution of the Gauss-Bonnet term leads to substantial deviations from Einstein gravity. We also discuss that after a certain value of $\alpha$, the theory admits higher maximum masses compared with general relativity, however, the causality condition is violated in the high-mass region. Finally, our results are compared with the recent observations data on mass-radius diagram.