Anisotropy of the Stochastic Gravitational Wave Background from Primordial Fluctuations

Gravitational waves produced in the primordial universe should show up as anisotropic stochastic gravitational wave backgrounds (GWB), similar to the cosmic microwave background (CMB). The GWB can carry the adiabatic perturbations as the CMB, or it can exhibit different energy fluctuations with non-minimal inflationary and reheating processes.

In this talk, I will use GW produced by a first-order phase transition as an example to consider the anisotropy of the GWB that is either correlated or un-correlated to the CMB fluctuations. I will also explain the possibility of seeing a large non-Gaussianity (NG) signal in the GWB while obeying current observational bounds. Finally, I will discuss the prospects of distinguishing cosmological signals from the astrophysical foreground.