Quark Stars in 4D Einstein-Gauss-Bonnet gravity with an Interacting Quark Equation of State

Abstract

The detection of gravitational waves (GWs) from the binary neutron star (BNS) has opened a new window on the gravitational wave astronomy. With current sensitivities, detectable signals coming from compact objects like neutron stars turn out to be a crucial ingredient for probing their structure, composition, and evolution. Moreover, the astronomical observations on the pulsars and their mass-radius relations put important constraints on the dense matter equation of state (EoS). In this paper, we consider a homogeneous and unpaired charge-neutral $3$-flavor interacting quark matter with $\mathcal{O}(m_s^4)$ corrections that account for the moderately heavy strange quark instead of the naive MIT bag model. In this article, we perform a detailed analysis of strange quark star in the context of recently proposed $4D$ Einstein-Gauss-Bonnet (EGB) theory of gravity. However, this theory does not have standard four-dimensional field equations. Thus, we thoroughly show that the equivalence of the actions in the regularized $4D$ EGB theory and in the original one is satisfied for a spherically symmetric spacetime. We pay particular attention to the possible existence of massive neutron stars of mass compatible with $M \sim 2 M_{\odot}$. Our findings suggest that the fourth-order corrections parameter ($a_4$) of the QCD perturbation and coupling constant $α$ of the GB term play an important role in the mass-radius relation as well as the stability of the quark star. Finally, we compare the results with the well-measured limits of the pulsars and their mass and radius extracted from the spectra of several X-ray compact sources.