Sensitivity of neutron star observations to three-nucleon forces

Astrophysical observations of neutron stars have been widely used to infer the properties of the nuclear matter equation of state. Beside being a source of information on average properties of dense matter, the data provided by electromagnetic and gravitational wave (GW) facilities are reaching the accuracy needed to constrain, for the first time, the underlying nuclear dynamics. In this work, we assess the sensitivity of current and future neutron star observations to directly infer the strength of repulsive three-nucleon forces, which are key to determine the stiffness of the equation of state. Using a Bayesian approach, we focus on the constraints that can be derived on three-body interactions from binary neutron star mergers observed by second- and third-generations of gravitational wave interferometers. We consider both single and multiple observations. For current detectors at design sensitivity, the analysis suggests that only low mass systems, with large signal-to-noise ratios, allow one to reliably constrain the three-body forces. However, our results show that a single observation with a third-generation interferometer, such as the Einstein Telescope or Cosmic Explorer, will constrain the strength of the repulsive three-nucleon potential with exquisite accuracy, turning third-generation GW detectors into new laboratories to investigate the properties of nucleon interactions.