A demonstration of improved constraints on primordial gravitational waves with delensing
We present a constraint on the tensor-to-scalar ratio, r, derived from measurements of cosmic microwave background (CMB) polarization B-modes with “delensing,” whereby the uncertainty on r contributed by the sample variance of the gravitational lensing B-modes is reduced by cross-correlating against...
Published in: | Physical Review D |
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Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
American Physical Society
2021
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Subjects: | |
Online Access: | https://authors.library.caltech.edu/107771/ https://authors.library.caltech.edu/107771/1/PhysRevD.103.022004.pdf https://authors.library.caltech.edu/107771/3/2011.08163.pdf https://resolver.caltech.edu/CaltechAUTHORS:20210127-093358968 |
Summary: | We present a constraint on the tensor-to-scalar ratio, r, derived from measurements of cosmic microwave background (CMB) polarization B-modes with “delensing,” whereby the uncertainty on r contributed by the sample variance of the gravitational lensing B-modes is reduced by cross-correlating against a lensing B-mode template. This template is constructed by combining an estimate of the polarized CMB with a tracer of the projected large-scale structure. The large-scale-structure tracer used is a map of the cosmic infrared background derived from Planck satellite data, while the polarized CMB map comes from a combination of South Pole Telescope, BICEP/Keck, and Planck data. We expand the BICEP/Keck likelihood analysis framework to accept a lensing template and apply it to the BICEP/Keck dataset collected through 2014 using the same parametric foreground modeling as in the previous analysis. From simulations, we find that the uncertainty on r is reduced by ∼10%, from σ(r) = 0.024 to 0.022, which can be compared with a ∼26% reduction obtained when using a perfect lensing template or if there were zero lensing B-modes. Applying the technique to the real data, the constraint on r is improved from r_(0.05) < 0.090 to r_(0.05) < 0.082 (95% C.L.). This is the first demonstration of improvement in an r constraint through delensing. |
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