Observational constraints on theories with a blue spectrum of tensor modes

Journal Article · Fri Aug 15 04:00:00 EDT 2008 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2008/08/012· OSTI ID:22156705

Stewart, Andrew; Brandenberger, Robert ^[1]

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1. Physics Department, McGill University, Montreal, QC, H3A 2T8 (Canada)

Motivated by the string gas cosmological model, which predicts a blue tilt of the primordial gravitational wave spectrum, we examine the constraints imposed by current and planned observations on a blue tilted tensor spectrum. Starting from an expression for the primordial gravitational wave spectrum normalized using cosmic microwave background observations, pulsar timing, direct detection and nucleosynthesis bounds are examined. If we assume a tensor-to-scalar ratio on scales of the cosmic microwave background which equals the current observational upper bound, we obtain from these current observations constraints on the tensor spectral index of n{sub T}{approx}<0.79, n{sub T}{approx}<0.53, and n{sub T}{approx}<0.15 respectively.

• OSTI ID: 22156705
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 08 Vol. 2008; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COSMOLOGICAL MODELS
DETECTION
GRAVITATIONAL WAVES
LIMITING VALUES
NUCLEOSYNTHESIS
PULSARS
RELICT RADIATION
SCALARS
SPECTRA
TENSORS