Quark stars with 2.6 $M_{\odot }$ in a non-minimal geometry-matter coupling theory of gravity

Abstract

This work analyses the hydrostatic equilibrium configurations of strange stars in a non-minimal geometry-matter coupling (GMC) theory of gravity. Those stars are made of strange quark matter, whose distribution is governed by the MIT equation of state. The non-minimal GMC theory is described by the following gravitational action: $f(R,L)=R/2+L+\ddot{I}ƒRL$, where $R$ represents the curvature scalar, $L$ is the matter Lagrangian density, and $\ddot{I}ƒ$ is the coupling parameter. When considering this theory, the strange stars become larger and more massive. In particular, when $\ddot{I}ƒ=50$ km${}^2$, the theory can achieve the 2.6 $M_{\odot }$, which is suitable for describing the pulsars PSR J2215+5135 and PSR J1614-2230, and the mass of the secondary object in the GW190814 event. The 2.6 $M_{\odot }$ is a value hardly achievable in General Relativity even considering fast rotation effects, and is also compatible with the mass of PSR J0952-0607 ($M=2.35\pm 0.17M_{\odot }$), the heaviest and fastest pulsar in the disk of the Milky Way, recently measured, supporting the possible existence of strange quark matter in its composition. The non-minimal GMC theory can also give feasible results to describe the macroscopical features of strange star candidates.