Pulsar Timing Arrays: Unveiling The Nanohertz-frequency Gravitational-wave Landscape

Pulsar-timing arrays (PTAs) like the North American Nanohertz Observatory for Gravitational waves (NANOGrav) and the International Pulsar Timing Array are poised to chart the new frontier of gravitational wave discovery within the next several years. At these frequencies, expected sources include supermassive black hole binaries, formed when galaxies merge over cosmic time, and emanating gravitational waves in the nanohertz-frequency sensitivity band of PTAs. I will present exciting new results from recent cutting-edge searches, discuss some milestones on the road to the next decade of PTA discovery, and highlight new techniques to enable the future multi-messenger detection of supermassive black-hole binaries.