Runaway Neutron Stars from Massive Binary Stellar Systems

As far as we know, most massive stars live in binary systems. Depending on the initial masses of the two stars, metallicity, and orbital separation, the system can experience different phases. Both stars may end their lives as supernovae, generating neutron stars (or black holes). Moreover, a kick is imparted to these objects after their birth. If the combination of magnitude and angle of the kick velocity vector makes the star overcome the gravitational potential of the system, then it can unbind the binary. This can happen at the first supernova explosion, where the system consists of a massive star and a neutron star that recede from each other, or at the second explosion, where two neutron stars move away in different directions, named here as runaway neutron stars. In this thesis, we explore the potential existence of massive binary systems that survived the first supernova explosion but were subsequently disrupted after the occurrence of the second supernova. To achieve this, the orbits of pairs of neutron stars are traced backward in time within the Galactic potential. Due to the uncertainty of measured parallax and proper motion and the lack of possible measurement of the radial velocity, Monte Carlo simulations are performed. The goal of this work is to identify pairs that were simultaneously closely situated both in space and time with a high probability. Two possible candidates have been found, and through statistical analyses and certain constraints, we discuss the validity of the results.