Graviton Spectra in String Cosmology

Abstract

We propose to uncover the signature of a stringy era in the primordial Universe by searching for a prominent peak in the relic graviton spectrum. This feature, which in our specific model terminates an ${\omega }^3$ increase and initiates an ${\omega }^{-7}$ decrease, is induced during the so far overlooked bounce of the scale factor between the collapsing deflationary era (or pre-Big Bang) and the expanding inflationary era (or post-Big Bang). We evaluate both analytically and numerically the frequency and the intensity of the peak and we show that they may likely fall in the realm of the new generation of interferometric detectors. The existence of a peak is at variance with ordinarily monotonic (either increasing or decreasing) graviton spectra of canonical cosmologies; its detection would therefore offer strong support to string cosmology.

14 pages, RevTex source and 6 figures.ps

References in corpus (4)

• Relic Gravitational Waves from String Cosmology
• Towards a Singularity-Free Inflationary Universe?
• Tree-level String Cosmology
• Graceful exit in quantum string cosmology

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• Dynamical back-reaction of relic gravitons
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• The First Space-Based Gravitational-Wave Detectors
• Early cosmology and the stochastic gravitational wave background
• The branch process of the cosmic strings
• Constraining string cosmology with the gravitational-wave background using the NANOGrav 15-year data set
• Search for stochastic gravitational-wave background from string cosmology with Advanced LIGO and Virgo's O1$\sim$O3 data
• Production and Detection of Cosmic Gravitational Wave Background in String Cosmology
• Testing string cosmology with gravity wave detectors