Blue Gravity Waves from BICEP2 ?

Abstract

We present new constraints on the spectral index n_T of tensor fluctuations from the recent data obtained by the BICEP2 experiment. We found that the BICEP2 data alone slightly prefers a positive, "blue", spectral index with n_T=1.36\pm0.83 at 68 % c.l.. However, when a TT prior on the tensor amplitude coming from temperature anisotropy measurements is assumed we get n_T=1.67\pm0.53 at 68 % c.l., ruling out a scale invariant $n_T=0$ spectrum at more than three standard deviations. These results are at odds with current bounds on the tensor spectral index coming from pulsar timing, Big Bang Nucleosynthesis, and direct measurements from the LIGO experiment. Considering only the possibility of a "red", n_T<0 spectral index we obtain the lower limit n_T > -0.76 at 68 % c.l. (n_T>-0.09 when a TT prior is included).

3 Pages, 4 Figures

References in corpus (12)

• BICEP2 I: Detection Of B-mode Polarization at Degree Angular Scales
• Starting the Universe: Stable Violation of the Null Energy Condition and Non-standard Cosmologies
• G-inflation: inflation driven by the Galileon field
• An Upper Limit on the Stochastic Gravitational-Wave Background of Cosmological Origin
• New Ekpyrotic Cosmology
• Producing a Scale-Invariant Spectrum of Perturbations in a Hagedorn Phase of String Cosmology
• A smooth bouncing cosmology with scale invariant spectrum
• Higgs G-inflation
• Inflation with violation of the null energy condition
• On the Initial Conditions in New Ekpyrotic Cosmology
• Observational Constraints on Theories with a Blue Spectrum of Tensor Modes
• Is Cosmology Compatible with Blue Gravity Waves ?

Cited by in corpus (26)

• Planck 2013 results. XXII. Constraints on inflation
• Primordial gravitational waves from NANOGrav: a broken power-law approach
• Blue Tensor Spectrum from Particle Production during Inflation
• Blue-tilted Tensor Spectrum and Thermal History of the Universe
• Updated Constraints and Forecasts on Primordial Tensor Modes
• Prospects for Delensing the Cosmic Microwave Background for Studying Inflation
• Multi-wavelength constraints on the inflationary consistency relation
• Neutrinos and dark energy after Planck and BICEP2: data consistency tests and cosmological parameter constraints
• Spectral distortions from the dissipation of tensor perturbations
• Inflation and Alternatives with Blue Tensor Spectra
• CMB $\mu$ distortion from primordial gravitational waves
• Scalar suppression on large scales in open inflation
• A model-independent fit to Planck and BICEP2 data
• Dynamical Fractional Chaotic Inflation -- Dynamical Generation of a Fractional Power-Law Potential for Chaotic Inflation
• Pre-inflationary genesis with CMB B-mode polarization
• Linking the BICEP2 result and the hemispherical power asymmetry through spatial variation of $r$
• Bekenstein-Hawking entropy in expanding universes from black hole theorems
• Isocurvature perturbations and tensor mode in light of Planck and BICEP2
• Revised cosmological parameters after BICEP 2 and BOSS
• Let Effective Field Theory of Inflation flow: stochastic generation of models with red/blue tensor tilt
• Ambiguity in running spectral index with an extra light field during inflation
• Tensors, BICEP2, prior dependence, and dust
• Precision of future experiments measuring primordial tensor fluctuation
• Constraining primordial vector mode from B-mode polarization
• Cosmological parameter fittings with the BICEP2 data
• Inflation after Planck and BICEP2