PREPRINT
C8565FA6-0701-42A5-B48C-BAE9CABCB7A8

Gravitational Wave Spectrum Induced by Primordial Scalar Perturbations

Daniel Baumann, Kiyotomo Ichiki, Paul J. Steinhardt, Keitaro Takahashi
arXiv:hep-th/0703290

Submitted on 30 March 2007

Abstract

We derive the complete spectrum of gravitational waves induced by primordial scalar perturbations ranging over all observable wavelengths. This scalar-induced contribution can be computed directly from the observed scalar perturbations and general relativity and is, in this sense, independent of the cosmological model for generating the perturbations. The spectrum is scale-invariant on small scales, but has an interesting scale-dependence on large and intermediate scales, where scalar-induced gravitational waves do not redshift and are hence enhanced relative to the background density of the Universe. This contribution to the tensor spectrum is significantly different in form from the direct model-dependent primordial tensor spectrum and, although small in magnitude, it dominates the primordial signal for some cosmological models. We confirm our analytical results by direct numerical integration of the equations of motion.

Preprint

Comment: 19 pages, 5 figures

Subjects: High Energy Physics - Theory; Astrophysics; General Relativity and Quantum Cosmology

URL: https://arxiv.org/abs/hep-th/0703290