Binary neutron stars (BNSs) are rare, compact stellar remnants that provide critical insights into stellar evolution, supernova physics, and Galactic dynamics. Their kinematics –positions, velocities, and trajectories within the host galaxy– encode the outcomes of two supernovae and the binary interactions that preceded them. By analyzing these motions, we can inform stellar models, formation channels, and binary survival rates. BNSs are also key progenitors of gravitational-wave events and a prime location of nucleosynthesis. Understanding their merger locations improves merger rate predictions, spatial localisation for gravitational-wave and electromagnetic counterparts, and our understanding of cosmic chemical enrichment. As BNS datasets grow and gravitational-wave observations become increasingly available, a comprehensive understanding of BNS kinematics becomes essential for interpreting the observed populations. This thesis addresses that need by focusing on the motion and merger locations of BNSs within their host galaxies, delivering a general theoretical framework for the motion of kicked objects in the Galactic potential, a comprehensive kinematical characterisation of the observed BNS in the Milky Way, and a predictive framework that connects BNS kinematics to the observed merger locations in external galaxies.
Nicola Gaspari grew up in the countryside south of Verona (Italy), in a small village called Ca' degli Oppi. He attended the Technical Institute G. Ferraris in Verona and graduated in 2011 as a chemical technician (perito chimico). After working for a few years in the industry as a chemical analyst, he moved to Padova and graduated from the University of Padova with a Bachelor’s degree in Astronomy in 2018 and a Master’s degree in Astronomy in 2020. In 2020 he joined the Department of Astrophysics at Radboud University as a Ph.D. candidate. Along with his individual theoretical work, he also worked within the operations teams of two international collaborations, performing optical/IR observations with world-class telescopes. He authored and co-authored 17 peer-reviewed papers, tutored university-level courses, delivered 5 conference talks, 3 invited seminars, and a public lecture.