The NANOGrav 15-year Data Set: Implications for Supermassive Black Hole Binaries

After more than 15 years of pulsar timing efforts to create a galactic-scale gravitational wave detector, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has uncovered evidence for a stochastic background of gravitational waves. While the most common predicted origin for this background is a population of supermassive black hole binaries (SMBHBs), more data will be needed to confirm either this hypothesis or an alternative source. In this talk, I will discuss the current constraints the 15-year data set places on SMBHB populations, and our efforts to tighten these constraints in future data sets. Additionally, I will summarize results from other SMBHB searches conducted on the 15-year data set through continuous wave analyses, including those informed by multi-messenger efforts, and lay out the future landscape towards an SMBHB detection with pulsar timing arrays.