The Proper Motion of Cygnus X-3

Cygnus X-3 is one of the brightest X-ray binary sources in the sky, particularly during its giant outbursts, when it launches relativistic jets which are seen to evolve on timescales of days. The location of the core of the binary system has hitherto been uncertain, hindering the interpretation of the complex morphologies observed in VLBI observations of the jets. In this project, we have looked at twenty-three years of archival data on Cygnus X-3 in order to constrain the proper motion of the system. From that proper motion, we can now determine the position of the core at any given time. The radial velocity of the system is unknown, with different authors deriving very disparate estimates. Using our measured proper motion and a model of the Galactic potential, we have determined the three-dimensional space velocities for the full range of radial velocities proposed in the literature. We use these space velocities to examine Cygnus X-3's orbital trajectory in the Galaxy, finding a minimum peculiar velocity of 40km/s. This information can be used to help constrain whether the system received a natal kick, allowing us to explore the formation mechanism of the compact object. We also determined the possible current locations of the supernova in which the compact object was formed, but current surveys of supernova remnants and OB associations do not extend far enough from the Sun to allow us to definitively identify the birthplace of Cygnus X-3.