A demonstration of improved constraints on primordial gravitational waves with delensing

• Published in: Physical Review D
• Main Authors: Ade, P. A. R., Ahmed, Z., Amiri, M., Anderson, A.J., Austermann, J.E., Avva, J.S., Barkats, D., Thakur, R. Basu, Beall, J.A., Bender, A.N., Benson, B.A., Bianchini, F., Bischoff, C.A., Bleem, L.E., Bock, J.J., Boenish, H., Bullock, E., Buza, V., Carlstrom, J.E., Chang, C.L., Cheshire, J.R., Chiang, H.C., Chou, T-L., Citron, R., Connors, J., Moran, C. Corbett, Cornelison, J., Crawford, T.M., Crites, A.T., Crumrine, M., Cukierman, A., de Haan, T., Dierickx, M., Dobbs, M.A., Duband, L., Everett, W., Fatigoni, S., Filippini, J.P., Fliescher, S., Gallicchio, J., George, E.M., Germaine, T.St., Goeckner-Wald, N., Goldfinger, D.C., Grayson, J., Gupta, N., Hall, G., Halpern, M., Halverson, N.W., Harrison, S., Henderson, S., Henning, J.W., Hildebrandt, S.R., Hilton, G.C., Holder, G.P., Holzapfel, W.L., Hrubes, J.D., Huang, N., Hubmayr, J., Hui, H., Irwin, K.D., Kang, J., Karkare, K.S., Karpel, E., Kefeli, S., Kernasovskiy, S.A., Knox, L., Kovac, J.M., Kuo, C.L., Lau, K., Lee, A.T., Leitch, E.?M., Li, D., Lowitz, A., Manzotti, A., McMahon, J.J., Megerian, K.G., Meyer, S.S., Millea, M., Mocanu, L.M., Moncelsi, L., Montgomery, J., Nadolski, A., Namikawa, T., Natoli, T., Netterfield, C.B., Nguyen, H.T., Nibarger, J.P., Noble, G., Novosad, V., O?Brient, R., Ogburn, R.W., Omori, Y., Padin, S., Palladino, S., Patil, S., Prouve, T., Pryke, C., Racine, B., Reichardt, C.L., Reintsema, C.D., Richter, S., Ruhl, J.E., Saliwanchik, B.R., Schaffer, K.K., Schillaci, A., Schmitt, B.L., Schwarz, R., Sheehy, C.D., Sievers, C., Smecher, G., Soliman, A., Stark, A.A., Steinbach, B., Sudiwala, R.V., Teply, G.P., Thompson, K.L., Tolan, J.E., Tucker, C., Turner, A.D., Umiltà, C., Veach, T., Vieira, J.D., Vieregg, A.G., Wandui, A., Wang, G., Weber, A.C., Whitehorn, N., Wiebe, D.V., Willmert, J., Wong, C.L., Wu, W.L.K., Yang, H., Yefremenko, V., Yoon, K.W., Young, E., Yu, C., Zeng, L., Zhang, C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Physical Society 2021
• Subjects: South Pole; South pole
• Online Access: https://orca.cardiff.ac.uk/id/eprint/138655/; https://doi.org/10.1103/PhysRevD.103.022004; https://orca.cardiff.ac.uk/id/eprint/138655/1/PhysRevD.103.022004.pdf

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.