No evidence for the blue-tilted power spectrum of relic gravitational waves

Journal Article · Mon Jun 01 04:00:00 EDT 2015 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2015/06/021· OSTI ID:22525779

Huang, Qing-Guo; Wang, Sai ^[1]

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1. State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Science, Beijing 100190 (China)

In this paper, we constrain the tilt of the power spectrum of relic gravitational waves by combining the data from BICEP2/Keck Array and Planck (BKP) and the Laser Interferometer Gravitational-Waves Observatory (LIGO). Supposing the linearly uniform priors for both the tensor-to-scalar ratio r and the tensor tilt n{sub t}, we find n{sub t}=0.66{sup +1.83}{sub −1.44} at the 68% confidence level from the data of BKP B-modes. By further adding the LIGO upper limit on the intensity of stochastic gravitational-wave background, the constraint becomes n{sub t}=−0.76{sup +1.37}{sub −0.52} at the 68% confidence level by assuming that the tensor amplitude has the similar order of the upper bounds from current CMB experiments. We find that there is no evidence for a blue-tilted power spectrum of relic gravitational waves and either sign of the index of tensor power spectrum is compatible with the current data.

• OSTI ID: 22525779
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 06 Vol. 2015; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ENERGY SPECTRA
GRAVITATIONAL WAVES
INTERFEROMETRY
LASER RADIATION
LIMITING VALUES
SCALARS
STOCHASTIC PROCESSES
TENSORS