Perspective in the Search for Relativistic Pulsars

Pulsar research makes major contributions to the field of fundamental physics, ranging from ultra-dense matter physics to relativistic gravity, cosmology and stellar evolution. A striking example is the confirmation of the existence of gravitational radiation, as predicted by Einstein's theory of General Relativity. Large scale surveys and searches carried out at radio wavelengths with large radio telescopes have greatly increased our understanding of the pulsar population, and have detected a number of peculiar objects. In the last few years, with a series of successful pulsar search experiments carried out usingthe Parkes 64m radio telescope in NSW (Australia), we have produced an unprecedented boom of radio pulsar discoveries, including the first ever known double-pulsar. The main virtue of the Parkes experiments has been the discovery of many pulsars which are intrinsically rare in the population, but very interesting for their physical applications. We have identified several young energetic pulsars, relativistic binary systems, binary pulsars with a massive star companion and millisecond pulsars in exotic binary systems.We have also used millisecond pulsar properties to probe the dynamical status of Globular Clusters, and we have found evidence of a high density of unseen dark remnants in a globular cluster. Future deep searches with similar equipment and long term timing programmes should produce many more exotic binary systems, and might represent the first real attempt to find a binary pulsar with a black hole companion. In this chapter we review the pulsar search techniques, with particular attention to the detection and precise timing of relativistic binaries, and their impact in our understanding of Gravitation.