Issue |
A&A
Volume 647, March 2021
|
|
---|---|---|
Article Number | A128 | |
Number of page(s) | 18 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361/202039585 | |
Published online | 19 March 2021 |
Planck constraints on the tensor-to-scalar ratio
1
Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France
e-mail: tristram@lal.in2p3.fr
2
Université de Toulouse, UPS-OMP, IRAP, 31028 Toulouse cedex 4, France
3
CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse cedex 4, France
4
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California, USA
5
Warsaw University Observatory, Aleje Ujazdowskie 4, 00-478 Warszawa, Poland
6
Computational Cosmology Center, Lawrence Berkeley National Laboratory, Berkeley, California, USA
7
Space Sciences Laboratory, University of California, Berkeley, California, USA
8
Institute of Theoretical Astrophysics, University of Oslo, Blindern, Oslo, Norway
9
Instituto de Física de Cantabria (CSIC-Universidad de Cantabria), Avda. de los Castros s/n, Santander, Spain
10
Haverford College Astronomy Department, 370 Lancaster Avenue, Haverford, Pennsylvania, USA
11
Department of Physics & Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia, Canada
Received:
2
October
2020
Accepted:
21
December
2020
We present constraints on the tensor-to-scalar ratio r using Planck data. We use the latest release of Planck maps, processed with the NPIPE code, which produces calibrated frequency maps in temperature and polarisation for all Planck channels from 30 GHz to 857 GHz using the same pipeline. We computed constraints on r using the BB angular power spectrum, and we also discuss constraints coming from the TT spectrum. Given Planck’s noise level, the TT spectrum gives constraints on r that are cosmic-variance limited (with σr = 0.093), but we show that the marginalised posterior peaks towards negative values of r at about the 1.2σ level. We derived Planck constraints using the BB power spectrum at both large angular scales (the ‘reionisation bump’) and intermediate angular scales (the ‘recombination bump’) from ℓ = 2 to 150 and find a stronger constraint than that from TT, with σr = 0.069. The Planck BB spectrum shows no systematic bias and is compatible with zero, given both the statistical noise and the systematic uncertainties. The likelihood analysis using B modes yields the constraint r < 0.158 at 95% confidence using more than 50% of the sky. This upper limit tightens to r < 0.069 when Planck EE, BB, and EB power spectra are combined consistently, and it tightens further to r < 0.056 when the Planck TT power spectrum is included in the combination. Finally, combining Planck with BICEP2/Keck 2015 data yields an upper limit of r < 0.044.
Key words: cosmology: observations / cosmic background radiation / cosmological parameters / gravitational waves / methods: data analysis
© M. Tristram et al. 2021
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.