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

TL;DR

This paper explores how a non-minimal gravity theory allows strange quark stars to reach masses up to 2.6 solar masses, explaining observed massive pulsars and compact objects better than standard gravity models.

Contribution

It demonstrates that a specific non-minimal geometry-matter coupling gravity theory can produce more massive strange stars, aligning with recent astrophysical observations.

Findings

Strange stars can reach 2.6 M_sun in this theory.

The theory explains massive pulsars like PSR J2215+5135.

Massive objects in GW190814 are compatible with strange stars.

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: $f(R,L)=R/2+L+\sigma RL$, where $R$ represents the curvature scalar, $L$ is the matter Lagrangian density, and $\sigma$ is the coupling parameter. When considering this theory, the strange stars become larger and more massive. In particular, when $\sigma=50$ 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 ($M = 2.35 \pm 0.17 ~M_\odot$), 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.