Constraint on the primordial gravitational waves from the joint analysis of BICEP2 and Planck HFI 353 GHz dust polarization data

TL;DR

This study combines BICEP2 and Planck HFI 353 GHz dust polarization data to constrain primordial gravitational waves, finding no evidence for them and placing upper limits on the tensor-to-scalar ratio, which challenges certain inflation models.

Contribution

It provides the first joint analysis of BICEP2 and Planck dust data to set tighter bounds on primordial gravitational waves and inflation models.

Findings

No evidence for primordial gravitational waves.

Upper bound on tensor-to-scalar ratio r<0.083 at 95% CL.

Starobinsky inflation model fits data well.

Abstract

We make a joint analysis of BICEP2 and recently released Planck HFI 353 GHz dust polarization data, and find that there is no evidence for the primordial gravitational waves and the bound on the tensor-to-scalar ratio becomes $r<0.083$ at $95%$ confidence level in the base $\Lambda$CDM + tensor model. Extending to the model with running of scalar spectral index, the bound is a little bit relaxed to $r<0.116$ at $95%$ confidence level. Our results imply that the inflation model with a single monomial potential is marginally disfavored at around $95%$ confidence level. Especially, the $m^2\phi^2/2$ inflation model is disfavored at more than $2\sigma$ level. However, the Starobinsky inflation model gives a nice fit.