Stability of a realistic astrophysical pulsar and its mass-radius relation in higher-order curvature gravity

TL;DR

This paper investigates the stability and mass-radius relation of astrophysical pulsars within a higher-order curvature gravity framework, providing analytical solutions for anisotropic stellar models and demonstrating their physical viability.

Contribution

It introduces an analytical approach to model pulsars in $ ext{R}+f( ext{G})$ gravity with quadratic Gauss-Bonnet terms, linking stellar structure parameters to stability and physical properties.

Findings

Model produces stable stellar configurations.

Analytical solutions relate pressure, density, and compactness.

Quadratic Gauss-Bonnet form enhances physical realism.

Abstract

The objective of this research is to explore compact celestial objects while considering the framework of an extended gravitational theory known as $\mathcal{R}+f(\mathcal{G})$ gravity. The notations $\mathcal{R}$ and $\mathcal{G}$ denote the Ricci scalar and the Gauss-Bonnet invariant, respectively. Radio pulsars, which are neutron stars with masses greater than 1.8 times that of the Sun ($M_\odot$), provide exceptional opportunities for delving into fundamental physics in extraordinary environments unparalleled in the observable universe and surpassing the capabilities of experiments conducted on Earth. Through the utilization of both the linear and quadratic expressions of the function { $f(\mathcal{G}) = \alpha_1 \mathcal{G}^2$, where $\alpha_1$ (with dimensional units of [${\textit length}^6$]) are incorporated}, we have achieved an accurate analytical solution for anisotropic perfect-fluid spheres in a state of hydrostatic equilibrium. By integrating the dimensional parameters $\alpha_1$ and the compactness factor, defined as ${\mathcal C=\frac{2GM}{Rc^2}}$, we showcase our capacity to encompass and depict all physical characteristics within the stellar structure. We illustrate that the model is capable of producing a stable arrangement encompassing its physical and geometric properties. We illustrate that by utilizing the quadratic form of $\mathcal{G}$ in the $\mathcal{R}+f(\mathcal{G})$ framework, the ansatz of Krori-Barua establishes connection between pressure in the radial direction ($p_r$) using semi-analytical methods, pressure in the tangential direction ($p_t$), and density ($\rho$).