Exploring the universal $\bar{\mathcal{I}}-\mathcal{C}$ relations for relativistic stars in $f(Q)$ gravity

Abstract: We investigate the properties of neutron stars within the framework of $f(Q)$ gravity by incorporating rotational effects through a slowly rotating metric, extending previous work. We derive the modified TOV equations and calculate the angular velocity profiles and moments of inertia for linear, quadratic, logarithmic, and exponential $f(Q)$ models. Our results show that deviations in the moment of inertia are more pronounced than those in the maximum mass, providing a strong constraint for alternative gravity theories. We also find a universal relation between the dimensionless moment of inertia and compactness, which shows distinct deviations from GR in $f(Q)$ models. Additionally, we analyze hybrid and quark star EoS, demonstrating consistency with the behavior observed in the calculation of the $\bar{I}-C$ relation for PSR J0737-3039A, which could be explored further and is interesting for future studies. Our findings suggest that $f(Q)$ gravity offers the possibility of being tested in the strong-field regime by examining the properties of compact objects and constraining the $f(Q)$ parameters through universal relations, such as the $I-C$ relation, in potential future observations.