Generation of gravitational waves from freely decaying turbulence

Understand

We study the stochastic gravitational wave background (SGWB) produced by freely decaying vortical turbulence in the early Universe.

• We thoroughly investigate the time correlation of the velocity field, and hence of the anisotropic stresses producing the gravitational waves.
• With hydrodynamical simulations, we show that the unequal time correlation function (UETC) of the Fourier components of the velocity field is Gaussian in the time difference, as predicted by the "sweeping" decorrelation model.
• We introduce a decorrelation model that can be extended to wavelengths around the integral scale of the flow.