Primordial Gravitational Wave- and Curvature Perturbation-Induced Energy Density Perturbations.

We study the second-order scalar and density perturbations generated by Gaussian curvature perturbations and primordial gravitational waves in the radiation-dominated era. After presenting all the possible second-order source terms, we obtain the explicit expressions of the kernel functions and the power spectra of the second-order scalar perturbations. We show that the primordial gravitational waves might affect second-order energy density perturbation δ (2) = δ ρ (2) / ρ (0) significantly. The effects of primordial gravitational waves are studied in terms of different kinds of primordial power spectra. [ABSTRACT FROM AUTHOR]