Spectrum of gravitational waves in Randall-Sundrum braneworld cosmology

Journal Article · Wed Feb 15 04:00:00 EST 2006 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PhysRevD.73.044005· OSTI ID:20776743

Kobayashi, Tsutomu; Tanaka, Takahiro ^[1]

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1. Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)

We study the generation and evolution of gravitational waves (tensor perturbations) in the context of Randall-Sundrum braneworld cosmology. We assume that the initial and final stages of the background cosmological model are given by de Sitter and Minkowski phases, respectively, and they are connected smoothly by a radiation-dominated phase. This setup allows us to discuss the quantum-mechanical generation of the perturbations and to see the final amplitude of the well-defined zero mode. Using the Wronskian formulation, we numerically compute the power spectrum of gravitational waves, and find that the effect of initial vacuum fluctuations in the Kaluza-Klein modes is subdominant, contributing not more than 10% of the total power spectrum. Thus it is confirmed that the damping due to the Kaluza-Klein mode generation and the enhancement due to the modification of the background Friedmann equation are the two dominant effects, but they cancel each other, leading to the same spectral tilt as the standard four-dimensional result. Kaluza-Klein gravitons that escape from the brane contribute to the energy density of the dark radiation at late times. We show that a tiny amount of the dark radiation is generated due to this process.

• OSTI ID: 20776743
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 4 Vol. 73; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
AMPLITUDES
COSMOLOGICAL MODELS
COSMOLOGY
DAMPING
DE SITTER GROUP
DISTURBANCES
ENERGY DENSITY
ENERGY SPECTRA
EVOLUTION
FIELD EQUATIONS
FLUCTUATIONS
GRAVITATIONAL WAVES
GRAVITONS
KALUZA-KLEIN THEORY
QUANTUM GRAVITY
QUANTUM MECHANICS
TENSORS