The European Pulsar Timing Array

A pulsar timing array (PTA) is a galaxy-scale detector of gravitational waves (GWs) based on the regular timing of an ensemble of pulsars. Possible sources are low-frequency nano-Hz GWs from the merger of supermassive black hole binaries at galaxy centers or from the physical processes in the early Universe. In 2023, several PTA collaborations around the world reported evidence for nano-Hz GWs. Europe has a long history and plays a crucial role in the global efforts for detecting GWs with PTAs. This article describes the history, data, early scientific results, and recent progress of the European PTA.