Gravitational scattering of compact objects: first matter simulations and challenges in gravitational wave detection

Abstract: In this talk I’m going to present the first numerical relativity simulations of gravitational scattering between neutron stars and the first comparison of such simulations with analytical predictions as well as the black hole case. Our results probe extreme strong-field regimes up to the threshold of dynamical capture, revealing both agreement and significant tidal discrepancies with effective-one-body and post-Minkowskian predictions. In addition, I will discuss the challenges in the gravitational wave numerical extraction and detection for this type of events: these configurations allow to build numerical relativity surrogates in order to tackle the parameter estimation task. Nevertheless, degeneracies can arise when using the Weyl Scalar waves to analyse the data and only some combination of parameters might be potentially measured. Finally, I will comment on the performance of the Regge-Wheeler-Zerilli-Moncrief metric extraction technique to obtain the strain waves in such events.