I will present a short review of the current status of nanohertz gravitational wave astronomy and the current status and near-future plans of pulsar timing array (PTAs) projects. I will discuss some of the most exciting results that have emerged from different PTA datasets, and how they have spurred research through varied attempts to interpret the current evidence, and the current efforts to make a 5-sigma detection of the nanohertz gravitational wave background (GWB). To achieve this milestone, PTA collaborations across the globe are uniting their data under the aegis of the IPTA, producing the largest PTA dataset to date. This dataset includes 121 pulsars from five regional PTAs, encompassing over a million individual pulsar observations. I will report on the status of IPTA-DR3 and demonstrate the anticipated sensitivity gained by this dataset in the search for the nHz GWB, as well as its ability to address the potential tension between theoretical expectations of the background and recent literature values. I will discuss the relevance of the IPTA DR3 in searches for individual supermassive black hole binaries and backgrounds of cosmological (or ‘new physics’) origin. I will demonstrate ongoing efforts to make use of some the most sensitive data to search for such sources, and present a new technique to search for signals from dark matter interactions. Finally, I will show how PTAs have the potential to connect large scale electromagnetic surveys with current and proposed experiments like the Square Kilometre Array PTA.
Prospects with nanohertz GW astronomy