Cosmic Variance Effects on Gravitational Wave Background Spectra

A Gravitational Wave Background (GWB) is the confusion noise from overlapping gravitational waves of astrophysical or cosmological origin. While they are modelled as stochastic, isotropic, and Gaussian processes, this assumption is only valid for isotropic cosmological sources and in the large number limit of astrophysical sources, as recent work shows. Cosmic variance introduces uncertainties in the predicted GWB strain due to wave interference effects and Poisson statistics, resulting in anisotropies and non-Gaussianity in certain regimes. In this talk, we will present our work on predicting GWB spectra and statistics incorporating cosmic variance effects, the limits it may place on parameter estimation, and our ability to distinguish between GWBs of different sources across the gravitational wave spectrum.