Anisotropic quark stars in $f(R,L_m,T)$ gravity

TL;DR

This paper explores how a modified gravity theory, $f(R,L_m,T)$, affects the structure and observable properties of quark stars, revealing potential deviations from predictions of general relativity.

Contribution

It introduces a specific $f(R,L_m,T)$ model with matter-geometry coupling, analyzes its impact on quark star structure, and constrains the coupling parameter using astrophysical data.

Findings

Coupling parameter $eta$ can increase or decrease quark star masses.

Mass-radius relations differ from general relativity predictions.

Constraints on $eta$ suggest possible observable effects in compact stars.

Abstract

We investigate the impact of $f(R,L_m,T)$ gravity on the internal structure of compact stars, expecting this theory to manifest prominently in the high-density cores of such stars. In this study, we begin by considering the algebraic function $f(R,L_m,T) = R + \alpha T L_m$, where $\alpha$ represents the matter-geometry coupling constant. We specifically choose the matter Lagrangian density $L_m= -\rho$ to explore compact stars with anisotropic pressure. To this end, we employ the MIT bag model as an equation of state. We then numerically solve the hydrostatic equilibrium equations to obtain mass-radius relations for quark stars, examining static stability criteria, the adiabatic index, and the speed of sound. Finally, we use recent astrophysical data to constrain the coupling parameter $\alpha$, which may lead to either larger or smaller masses for quark stars compared to their counterparts in general relativity.