  Primordial gravitational waves are expected to create a stochastic background
encoding information about the early Universe that may not be accessible by
other means. However, the primordial background is obscured by an astrophysical
foreground consisting of gravitational waves from compact binaries. We
demonstrate a Bayesian method for estimating the primordial background in the
presence of an astrophysical foreground. Since the background and foreground
signal parameters are estimated simultaneously, there is no subtraction step,
and therefore we avoid astrophysical contamination of the primordial
measurement, sometimes referred to as "residuals". Additionally, since we
include the non-Gaussianity of the astrophysical foreground in our model, this
method represents the statistically optimal approach to the simultaneous
detection of a multi-component stochastic background.
