Modeling the Population of Gravitational Wave Sources for Pulsar Timing Arrays

Pulsar Timing Arrays (PTA) are galactic-scale low-frequency gravitational wave observatories. The primary source of gravitational radiation in this band is expected to come from a cosmic population of binary supermassive black holes (SMBHs) that form following galactic mergers. However, there are many open questions regarding the merger dynamics of binary SMBHs, and the relationship between a central black hole and its host galaxy. Using a new simulation, which incorporates the latest observational estimates of galaxy parameters including an updated empirical measurement of the galaxy merger rate, I investigate open questions around the spectral shape and amplitude of the gravitational wave background, and the stochastic nature of the signal including the resolvability of discrete binaries in the PTA band.