The inflationary gravitational-wave background and measurements of the scalar spectral index

Abstract

Inflation predicts a stochastic background of gravitational waves over a broad range of frequencies, from those accessible with cosmic microwave background (CMB) measurements, to those accessible directly with gravitational-wave detectors, like NASA's Big-Bang Observer (BBO), currently under study. In a previous paper [Phys. Rev. D73, 023504 (2006)] we connected CMB constraints to the amplitude and tensor spectral index of the inflationary gravitational-wave background (IGWB) at BBO frequencies for four classes of models of inflation by directly solving the inflationary equations of motion. Here we extend that analysis by including results obtained in the WMAP third-year data release as well as by considering two additional classes of inflationary models. As often noted in the literature, the recent indication that the primordial density power-spectrum has a red spectral index implies (with some caveats) that the amplitude of the IGWB may be large enough to be observable in the CMB polarization. Here we also explore the implications for the direct detection of the IGWB.

7 pages, 7 figures, submitted to PRD

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• Reheating constraints to inflationary models
• Probing reheating temperature of the universe with gravitational wave background
• Primordial Gravitational Waves from Axion-Gauge Fields Dynamics
• Precision calculations of the gravitational wave background spectrum from inflation
• Inflationary tensor fossils in large-scale structure
• Gravitational waves from fragmentation of a primordial scalar condensate into Q-balls
• Gravitational waves from the fragmentation of a supersymmetric condensate
• Implications of the B-mode Polarization Measurement for Direct Detection of Inflationary Gravitational Waves
• Gravitational waves, dark energy and inflation
• Higgs Inflation, Quantum Smearing and the Tensor to Scalar Ratio
• Studying Inflation with Future Space-Based Gravitational Wave Detectors
• Probing the primordial universe with gravitational waves detectors
• First constraints on non-minimally coupled Natural and Coleman-Weinberg inflation and massive neutrino self-interactions with Planck+BICEP/Keck
• The History of Inflation from Microwave Background Polarimetry and Laser Interferometry