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arXiv · 2112.07961

Improved limits on the tensor-to-scalar ratio using BICEP and Planck

M. Tristram·A. J. Banday·K. M. Górski·R. Keskitalo·C. R. Lawrence·K. J. Andersen·R. B. Barreiro·J. Borrill·L. P. L. Colombo·H. K. Eriksen·R. Fernandez-Cobos·T. S. Kisner·E. Martínez-González·B. Partridge·D. Scott·T. L. Svalheim·I. K. Wehus
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Abstract

We present constraints on the tensor-to-scalar ratio r using a combination of BICEP/Keck 2018 and Planck PR4 data allowing us to fit for r consistently with the six parameters of the $Λ$CDM model without fixing any of them. In particular, we are able to derive a constraint on the reionization optical depth $τ$ and thus propagate its uncertainty onto the posterior distribution for r. While Planck sensitivity to r is no longer comparable with ground-based measurements, combining Planck with BK18 and BAO gives results consistent with r = 0 and tightens the constraint to r < 0.032.

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M. Tristram, A. J. Banday, K. M. Górski, R. Keskitalo, C. R. Lawrence, K. J. Andersen, R. B. Barreiro, J. Borrill, L. P. L. Colombo, H. K. Eriksen, R. Fernandez-Cobos, T. S. Kisner, E. Martínez-González, B. Partridge, D. Scott, T. L. Svalheim, I. K. Wehus. 2022-06-27. Improved limits on the tensor-to-scalar ratio using BICEP and Planck. https://doi.org/10.1103/physrevd.105.083524

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