The effect of pressure anisotropy on quark stars structure in the Starobinsky model

Abstract

The structure and stability of quark stars (QSs) made of interacting quark matter are discussed in this study, taking color superconductivity and perturbative QCD corrections into account. By combining this EoS with the Tolman-Oppenheimer-Volkoff (TOV) equations, we explore the mass-radius ($M-R$) relations of QSs. The analysis is conducted within the framework of $R^2$ gravity, where the gravity model is described by $f(R)=R+a{R}^2$. Our primary goal is to investigate how variations in the $R^2$ gravity parameter $a$ affect the mass-radius and mass-central density ($M-{\rho }_c$) relationships of QSs. Furthermore, we study the dynamical stability of these stars by analyzing the impact of anisotropy parameters $\beta$ and the interaction parameter $\lambda$ derived from the EoS, on their stability. Our results demonstrate that the presence of pressure anisotropy plays a significant role in increasing the maximum mass of QSs, with potential implications for the existence of super-massive pulsars. These findings are in agreement with recent astronomical observations, which suggest the possibility of neutron stars exceeding $2M_{\odot }$.

Comments: 14 pages and 9 Figures: Accepted Manuscript online 23 April 2025; Chinese Physics C