Tolman-Oppenheimer-Volkoff equations in non-local $f(R)$ gravity

TL;DR

This paper derives and numerically solves the modified Tolman-Oppenheimer-Volkoff equations within a non-local $f(R)$ gravity framework to model compact stars, highlighting potential astrophysical applications and observational relevance.

Contribution

It formulates the TOV equations for non-local $f(R)$ gravity and provides numerical solutions for specific compact stars, advancing understanding of such models in astrophysics.

Findings

Numerical solutions for star models Her X-1, SAX J 1808.4-3658, and 4U 1820-30.

Derived an empirical equation of state for compact stars.

Demonstrated the applicability of non-local $f(R)$ gravity to astrophysical objects.

Abstract

Non-local $f(R)$ gravity was proposed as a powerfull alternative to general relativity (GR) . This theory has potentially adverse implications for infrared (IR) regime as well as ultraviolent(UV) early epochs. However, there are a lot of powerful features, making it really user-friendly. A scalar-tensor frame comprising two auxiliary scalar fields, used to reduce complex action. However this is not the case for the modification complex which plays a distinct role in modified theories for gravity. In this work, we study the dynamics of a static, spherically symmetric object. The interior region of spacetime had rapidly filled the perfect fluid. However, it is possible to derive a physically based model which relates interior metric to non-local $f(R)$. The Tolman-Oppenheimer-Volkoff (TOV) equations would be a set of first order differential equations from which we can deduce all mathematical (physical) truths and derive all dynamical objects. This set of dynamical equations govern pressure $p$, density $\rho$, mass $m$ and auxiliary fields $\{\psi,\xi\}$. The full conditional solutions are evaluated and inverted numerically to obtain exact forms of the compact stars Her X-1, SAX J 1808.4-3658 and 4U 1820-30 for non-local Starobinsky model of $f(\Box^{-1}R)=\Box^{-1}R+\alpha \Big(\Box^{-1}R\Big)^2$. The program solves the differential equations numerically using adaptive Gaussian quadrature. An ascription of correctness is supposed to be an empirical equation of state $\frac{P}{P_c}= a (1- e^{-b\frac{\rho}{\rho_c}})$ for star which is informative in so far as it excludes an alternative non local approach to compact star formation. This model is most suited for astrophysical observation.