Artist's impression of the Double Pulsar system
showing the interaction of two radio beams.
The Double Pulsar provides an amazing laboratory for the study of relativistic gravity and the most precise test to date of General Relativity in the strong-field regime3. The two pulsars orbit each other in a 2.4-hr orbit, the shortest of any observed double neutron star systems, with moderate orbital eccentricity of 0.088. The first-born pulsar, pulsar A, has a short spin period of 23 ms and the second-born companion, pulsar B, spins with a longer 2.8 s period. Due to almost edge-on orbital plane of the system, the eclipses of pulsar A by pulsar B have been detected. Also, the strong stellar wind produced by the high energy loss from pulsar A distorts the magnetosphere of its companion pulsar B4,5,14. Thus, the Double Pulsar offers a unique opportunity to probe directly the magnetospheric structures and the plasma properties of pulsars in general.
With strong gravitational fields and rapid motions of the two pulsars in a tight binary, the system is expected to show large relativistic effects. The required parameters to explain the Keplerian orbits of the system and their relativistic corrections have been measured through pulsar timing3. Due to relativistic spin precession, the spin axis of the pulsar precesses around the orbital angular momentum of the system. This results a modulation in observed radio emission properties, namely pulse profiles and flux densities. As a result, the radio emission from pulsar B disappeared in 2008 towards our line of sight6. Based on geometry models, the reappearance of B's radio emission is expected to happen between 2014 and 2024. We here at JBCA use the Lovell Telescope to monitor the system since its discovery.