Neutron-star Radius Constraints from GW170817 and Future Detections

Abstract We introduce a new, powerful method to constrain properties of neutron stars (NSs). We show that the total mass of GW170817 provides a reliable constraint on the stellar radius if the merger did not result in a prompt collapse as suggested by the interpretation of associated electromagnetic emission. The radius of nonrotating NSs with a mass of 1.6 can be constrained to be larger than km, and the radius R max of the nonrotating maximum-mass configuration must be larger than km. We point out that detections of future events will further improve these constraints. Moreover, we show that a future event with a signature of a prompt collapse of the merger remnant will establish even stronger constraints on…