Astrophysics Webinar

The current generation of gravitational-wave detectors has revealed a rapidly growing population of compact-binary mergers, enabling direct studies of black-hole and neutron-star astrophysics. However, a large fraction of mergers occurring throughout cosmic history remain individually undetectable and contribute instead to a stochastic gravitational-wave background. Traditionally, searches for this background rely on cross-correlation techniques that treat the signal as Gaussian and stationary. While powerful for detecting a broadband background, these approaches do not fully exploit the rich astrophysical information encoded in the non-Gaussian and transient nature of the compact-binary population.

In this talk, I will describe a templated search framework designed to extract astrophysical information from this unresolved population. By combining short-duration template-based analyses with hierarchical population inference, this approach enables constraints on the mass, spin, and redshift distributions of compact binaries beyond the individually detected events. I will discuss the statistical framework underlying the method, the main challenges arising from detector noise and non-Gaussianity, and the strategies developed to address them.

Finally, I will show how measurements of the unresolved merger population can inform broader astrophysical and cosmological questions. In particular, I will discuss implications for the formation channels of compact binaries, the cosmic star-formation history, and the origin of heavy elements through r-process nucleosynthesis. These results illustrate how gravitational-wave observations can probe astrophysical processes that are otherwise inaccessible through electromagnetic observations alone.