Mass and Radius Relations of Quarkyonic Stars Using an Excluded-volume Model

Inspired by the excluded-volume model for isospin symmetric quarkyonic matter of Jeong et al., we construct an excluded-volume model for a charge-neutral quarkyonic phase whose hadronic sector contains only neutrons. We refer to this model as quarkyonic neutron matter. We compute the equation of state for this model and solve the Tolman-Oppenhermer-Volkoff equations to obtain mass and radius relations relevant for neutron stars. The most straightforward extension of the model for symmetric quarkyonic matter of Jeong et al. to quarkyonic neutron matter does not satisfy the mass-radius constraints from neutron star measurements. However, we show that by incorporating appropriate nuclear interactions in the excluded-volume model, one can produce mass-radius relations that lie within the constraints obtained from gravitational waves of binary neutron star mergers and maximum-mass measurements of neutron stars.