The European Pulsar Timing Array and the Large European Array for Pulsars

The European Pulsar Timing Array (EPTA) and the Large European Array for Pulsars (LEAP) play crucial roles in the global effort to detect gravitational waves (GWs) with a Pulsar Timing Array (PTA) experiment. While the EPTA uses five of the world's largest cm-radio telescopes, LEAP harvests their combined power to synthesize a 194 m equivalent dish to provide high-precision PTA data for most of the sky. The EPTA has already produced a large variety of results, including astrophysical studies of individual pulsars, tests of theories of gravity, stringent limits on a GW background produced by super-massive binary black holes or the vibration of cosmic strings. It has also undertaken the development of new analysis methods and techniques, and studies of the astrophysics and population of expected GW background sources. This review gives an overview of the EPTA and LEAP set-ups and corresponding activities.