Improved limits on the tensor-to-scalar ratio using BICEP and P l a n c k data

We present constraints on the tensor-to-scalar ratio $r$ using a combination of BICEP/Keck 2018 (BK18) and Planck PR4 data allowing us to fit for $r$ consistently with the six parameters of the $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ model. We discuss the sensitivity of constraints on $r$ to uncertainties in the $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ parameters as defined by the Planck data. In particular, we are able to derive a constraint on the reionization optical depth $\ensuremath{\tau}$ and thus propagate its uncertainty into the posterior distribution for $r$. While Planck sensitivity to $r$ is slightly lower than the current ground-based measurements, the combination of Planck with BK18 and…

• UD
  U.S. Department of Energy

  Award: DE-AC02-05CH11231
• NA
  National Aeronautics and Space Administration

  Award: 80NM0018D0004
• CI
  California Institute of Technology
• NE
  National Energy Research Scientific Computing Center
• ES
  European Space Agency
• CN
  Centre National de la Recherche Scientifique
• JP
  Jet Propulsion Laboratory
• IN
  Institut National de Physique Nucléaire et de Physique des Particules