Towards Rigorous Inference of Nanohertz Gravitational Waves

This thesis explores one of the most exciting frontiers in astrophysics: the search for gravitational waves, ripples in space and time created by the collision of supermassive black holes in distant galaxies. The work uses pulsar timing arrays, a network of extremely precise cosmic clocks, to distinguish genuine gravitational wave signals from background noise and instrumental effects that can mimic them. By testing and refining detection methods, the research shows how to avoid false alarms and how to extract reliable information from these faint cosmic hum. The results strengthen the foundations of this new window on the universe and its most powerful events.