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Constraints on Primordial Gravitational Waves Using Planck, WMAP, and New BICEP2/Keck Observations through the 2015 Season

Ade, P. A. R. and Aikin, R. W. and Bock, J. J. and Brevik, J. A. and Hildebrandt, S. R. and Hui, H. and Kefeli, S. and Lueker, M. and Moncelsi, L. and O'Brient, R. and Schillaci, A. and Soliman, A. and Staniszewski, Z. K. and Steinbach, B. and Teply, G. P. and Wandui, A. and Zhang, C. (2018) Constraints on Primordial Gravitational Waves Using Planck, WMAP, and New BICEP2/Keck Observations through the 2015 Season. Physical Review Letters, 121 (22). Art. No. 221301. ISSN 0031-9007.

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We present results from an analysis of all data taken by the BICEP2/Keck CMB polarization experiments up to and including the 2015 observing season. This includes the first Keck Array observations at 220 GHz and additional observations at 95 and 150 GHz. The Q and U maps reach depths of 5.2, 2.9, and 26  μK_(CMB) arcmin at 95, 150, and 220 GHz, respectively, over an effective area of ≈400 square degrees. The 220 GHz maps achieve a signal to noise on polarized dust emission approximately equal to that of Planck at 353 GHz. We take auto and cross spectra between these maps and publicly available WMAP and Planck maps at frequencies from 23 to 353 GHz. We evaluate the joint likelihood of the spectra versus a multicomponent model of lensed-ΛCDM+r+dust+synchrotron+noise. The foreground model has seven parameters, and we impose priors on some of these using external information from Planck and WMAP derived from larger regions of sky. The model is shown to be an adequate description of the data at the current noise levels. The likelihood analysis yields the constraint r_(0.05)<0.07 at 95% confidence, which tightens to r_(0.05)<0.06 in conjunction with Planck temperature measurements and other data. The lensing signal is detected at 8.8σ significance. Running a maximum likelihood search on simulations we obtain unbiased results and find that σ(r)=0.020. These are the strongest constraints to date on primordial gravitational waves.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ade, P. A. R.0000-0002-5127-0401
Bock, J. J.0000-0002-5710-5212
Moncelsi, L.0000-0002-4242-3015
Zhang, C.0000-0001-8288-5823
Alternate Title:BICEP2/Keck Array x: Constraints on Primordial Gravitational Waves using Planck, WMAP, and New BICEP2/Keck Observations through the 2015 Season
Additional Information:© 2018 American Physical Society. Received 2 July 2018; revised manuscript received 28 August 2018; published 27 November 2018. The bicep2/Keck Array projects have been made possible through a series of grants from the National Science Foundation including No. 0742818, No. 0742592, No. 1044978, No. 1110087, No. 1145172, No. 1145143, No. 1145248, No. 1639040, No. 1638957, No. 1638978, and No. 1638970, and by the Keck Foundation. The development of antenna-coupled detector technology was supported by the JPL Research and Technology Development Fund, and by NASA Grants No. 06-ARPA206-0040, No. 10-SAT10-0017, No. 12-SAT12-0031, No. 14-SAT14-0009, No. 16-SAT-16-0002. The development and testing of focal planes were supported by the Gordon and Betty Moore Foundation at Caltech. Readout electronics were supported by a Canada Foundation for Innovation grant to UBC. Support for quasi-optical filtering was provided by UK STFC Grant No. ST/N000706/1. The computations in this Letter were run on the Odyssey cluster supported by the FAS Science Division Research Computing Group at Harvard University. The analysis effort at Stanford and S. L. A. C. is partially supported by the U.S. DOE Office of Science. We thank the staff of the U.S. Antarctic Program and in particular the South Pole Station without whose help this research would not have been possible. Most special thanks go to our heroic winter-overs Robert Schwarz and Steffen Richter. We thank all those who have contributed past efforts to the BICEP-Keck Array series of experiments, including the bicep1 team. We also thank the Planck and WMAP teams for the use of their data, and are grateful to the Planck team for helpful discussions including on the use of the τ prior in Fig. 5.
Group:Astronomy Department
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
JPL Research and Technology Development FundUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Canada Foundation for InnovationUNSPECIFIED
Science and Technology Facilities Council (STFC)ST/N000706/1
Harvard UniversityUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Issue or Number:22
Record Number:CaltechAUTHORS:20181128-142206874
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91312
Deposited By: Tony Diaz
Deposited On:28 Nov 2018 22:50
Last Modified:09 Mar 2020 13:19

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