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.
• Language: unknown
• Published: 2022
• Subjects: 79 ASTRONOMY AND ASTROPHYSICS; South Pole; South pole
• Online Access: http://www.osti.gov/servlets/purl/1778812; https://www.osti.gov/biblio/1778812; https://doi.org/10.1103/physrevd.103.022004

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 data set collected through 2014 using the same parametric foreground modelling as in the previous analysis. From simulations, we find that the uncertainty on $r$ is reduced by $\sim10\%$, from $\sigma(r)$= 0.024 to 0.022, which can be compared with a $\sim26\%$ reduction obtained when using a perfect lensing template. 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.). Furthermore, this is the first demonstration of improvement in an $r$ constraint through delensing.