Stochastic gravitational wave background from cold dark matter halos

The current knowledge of cosmological structure formation suggests that Cold Dark Matter (CDM) halos possess a non-spherical density profile, implying that cosmic structures can be potential sources of gravitational waves via power transfer from scalar perturbations to tensor metric modes in the non-linear regime. By means of a previously developed mathematical formalism and a triaxial collapse model, we numerically estimate the stochastic gravitational-wave background generated by CDM halos during the fully non-linear stage of their evolution. Our results suggest that the energy density associated with this background is comparable to that produced by primordial tensor modes at frequencies ν ≈ 10−10Hz if the energy scale of inflation is V 1/4 ≈ 1−2×10 GeV, and that these gravitational waves could give rise to several cosmological effects, including secondary CMB anisotropy and polarization.