Gravitational wave fossils in nonlinear regime: halo tidal bias and intrinsic alignments from gravitational wave separate universe simulations

Understand

We investigate impacts of long-wavelength gravitational waves (GWs) on nonlinear structure formation by utilizing the tidal separate universe simulations.

• Based on the equivalence of a long-wavelength GW to a uniform tidal field in a local frame, we provide a way to incorporate a long-wavelength GW into the tidal separate universe simulation as an effective anisotropic expansion.
• This methodology enables us to study effects of GWs on large-scale structure efficiently.
• We measure the anisotropic imprint in the local power spectrum from the tidal separate universe simulations with GWs, which corresponds to the scalar-scalar-tensor bispectrum in squeezed limit or the so-called power spectrum response to GWs.