Graphics: Upper Limits on the Tensor to Scalar Power Ratio

A measurement of the tensor to scalar power ratio, r, would constrain the energy scale of inflation. There is no detection at present, but recent limits on r, evaluated at a pivot scale of 0.05 Mpc-1, are shown in the following plot. This graphic is not intended to illustrate a complete history, but rather provides a snapshot of current upper limits as experiments continue to search for a detection. Please acknowledge LAMBDA when using these images.


BICEP/Keck 2021 (arXiv, ADS)
Planck PR4 2020 (arXiv, ADS)
BICEP2/Keck 2018 (arXiv, ADS)

A service of the HEASARC and of the Astrophysics Science Division at NASA/GSFC
Goddard Space Flight Center, National Aeronautics and Space Administration
HEASARC Director: Dr. Alan P. Smale
LAMBDA Director: Dr. Thomas M. Essinger-Hileman
NASA Official: Dr. Thomas M. Essinger-Hileman
Web Curator: Mr. Michael R. Greason