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

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

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, and I. K. Wehus

Phys. Rev. D 105, 083524 – Published 26 April 2022

Abstract

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 $Λ CDM$ model. We discuss the sensitivity of constraints on $r$ to uncertainties in the $Λ CDM$ parameters as defined by the Planck data. In particular, we are able to derive a constraint on the reionization optical depth $τ$ 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 baryon-acoustic-oscillation data yields results consistent with $r = 0$ and tightens the constraint to $r < 0.032$ at 95% confidence.

Received 15 December 2021
Accepted 1 April 2022

DOI:https://doi.org/10.1103/PhysRevD.105.083524

Physics Subject Headings (PhySH)

Cosmic microwave background Cosmological parameters Inflation

Gravitation, Cosmology & Astrophysics

Authors & Affiliations

M. Tristram ¹, A. J. Banday², K. M. Górski^3,4, R. Keskitalo ^5,6, C. R. Lawrence³, K. J. Andersen⁷, R. B. Barreiro ⁸, J. Borrill^5,9, L. P. L. Colombo ¹⁰, H. K. Eriksen⁷, R. Fernandez-Cobos ¹¹, T. S. Kisner ^5,6, E. Martínez-González⁸, B. Partridge¹², D. Scott ¹³, T. L. Svalheim ⁷, and I. K. Wehus ⁷

¹Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France
²IRAP, Université de Toulouse, CNRS, CNES, UPS, (Toulouse), France
³Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California, USA
⁴Warsaw University Observatory, Aleje Ujazdowskie 4, 00-478 Warszawa, Poland
⁵Computational Cosmology Center, Lawrence Berkeley National Laboratory, Berkeley, California, USA
⁶Department of Physics and Space Sciences Laboratory, University of California, Berkeley, California, USA
⁷Institute of Theoretical Astrophysics, University of Oslo, Blindern, Oslo, Norway
⁸Instituto de Física de Cantabria (CSIC-Universidad de Cantabria), Avda. de los Castros s/n, Santander, Spain
⁹Space Sciences Laboratory, University of California, Berkeley, California, USA
¹⁰Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria, 16, Milano, Italy
¹¹Dpto. de Matemàticas, Estadística y Computación, Universidad de Cantabria, Avda. de los Castros s/n, E-39005 Santander, Spain
¹²Haverford College Astronomy Department, 370 Lancaster Avenue, Haverford, Pennsylvania, USA
¹³Department of Physics & Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia, Canada

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Vol. 105, Iss. 8 — 15 April 2022

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