Stochastic Gravitational Wave Background in Brane World Cosmology

TL;DR

This paper studies how gravitational waves evolve in brane world cosmology, revealing significant differences in the stochastic background spectrum compared to standard models, especially at high frequencies.

Contribution

It numerically analyzes the evolution of gravitational waves in brane world models, showing altered spectra at frequencies above a certain threshold.

Findings

The gravitational wave spectrum is significantly altered at frequencies above ~10^{-4} Hz.

The spectrum deviates from standard inflationary models in the high-frequency range.

The results depend on the anti de-Sitter curvature scale set at about 1 mm.

Abstract

We investigate the cosmological evolution of gravitational waves in Friedman-Robertson-Walker brane world models embedded in a five dimensional anti de-Sitter spacetime. To predict the spectrum of stochastic gravitational background at present generated in the inflationary phase, we numerically calculate the evolution of gravitational waves according to the method developed in our previous paper [K. Ichiki and K. Nakamura, arXiv:hep-th/0310282]. The resulting logarithmic energy spectrum is significantly altered from that of the standard four dimensional inflationary models in the frequency range f > f_{AdS} ~ 10^{-4} Hz, which corresponds to the curvature scale we set of anti de-Sitter spacetime, $l ~ 1$mm.