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LiteBIRD Science Goals and Forecasts: Improving Sensitivity to Inflationary Gravitational Waves with Multitracer Delensing

Namikawa, T., Lonappan, A. I., Baccigalupi, C., Bartolo, N., Beck, D., Benabed, K., Challinor, A., Diego-Palazuelos, P., Errard, J., Farrens, S., Gruppuso, A., Krachmalnicoff, N., Migliaccio, M., Martínez-González, E., Pettorino, V., Piccirilli, G., Ruiz-Granda, M., Sherwin, B., Starck, J., Vielva, P., Akizawa, R., Anand, A., Aumont, J., Aurlien, R., Azzoni, S., Ballardini, M., Banday, A. J., Barreiro, R. B., Bersanelli, M., Blinov, D., Bortolami, M., Brinckmann, T., Calabrese, E. ORCID:, Campeti, P., Carones, A., Carralot, F., Casas, F. J., Cheung, K., Clermont, L., Columbro, F., Conenna, G., Coppolecchia, A., Cuttaia, F., D'Alessandro, G., de Bernardis, P., de Haan, T., De Petris, M., Della Torre, S., Di Giorgi, E., Eriksen, H. K., Finelli, F., Franceschet, C., Fuskeland, U., Galloni, G., Galloway, M., Georges, M., Gerbino, M., Gervasi, M., Ghigna, T., Giardiello, S., Gimeno-Amo, C., Gjerløw, E., Hazumi, M., Henrot-Versillé, S., Hergt, L. T., Hivon, E., Kohri, K., Komatsu, E., Lamagna, L., Lattanzi, M., Leloup, C., Lembo, M., López-Caniego, M., Luzzi, G., Maffei, B., Masi, S., Massa, M., Matarrese, S., Matsumura, T., Micheli, S., Moggi, A., Monelli, M., Montier, L., Morgante, G., Mot, B., Mousset, L., Nagata, R., Natoli, P., Novelli, A., Obata, I., Occhiuzzi, A., Pagano, L., Paiella, A., Paoletti, D., Pascual-Cisneros, G., Pavlidou, V., Piacentini, F., Pinchera, M., Pisano, G., Polenta, G., Puglisi, G., Remazeilles, M., Ritacco, A., Rizzieri, A., Rubino-Martin, J., Sakurai, Y., Scott, D., Shiraishi, M., Signorelli, G., Stever, S. L., Takase, Y., Tanimura, H., Tartari, A., Tassis, K., Terenzi, L., Tristram, M., Vacher, L., van Tent, B., Wehus, I. K., Weymann-Despres, G., Zannoni, M. and Zhou, Y. 2023. LiteBIRD Science Goals and Forecasts: Improving Sensitivity to Inflationary Gravitational Waves with Multitracer Delensing. [Online]. arXiv: Cornell University. Available at:

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We estimate the efficiency of mitigating the lensing $B$-mode polarization, the so-called delensing, for the $LiteBIRD$ experiment with multiple external data sets of lensing-mass tracers. The current best bound on the tensor-to-scalar ratio, $r$, is limited by lensing rather than Galactic foregrounds. Delensing will be a critical step to improve sensitivity to $r$ as measurements of $r$ become more and more limited by lensing. In this paper, we extend the analysis of the recent $LiteBIRD$ forecast paper to include multiple mass tracers, i.e., the CMB lensing maps from $LiteBIRD$ and CMB-S4-like experiment, cosmic infrared background, and galaxy number density from $Euclid$- and LSST-like survey. We find that multi-tracer delensing will further improve the constraint on $r$ by about $20\%$. In $LiteBIRD$, the residual Galactic foregrounds also significantly contribute to uncertainties of the $B$-modes, and delensing becomes more important if the residual foregrounds are further reduced by an improved component separation method.

Item Type: Website Content
Date Type: Published Online
Status: Submitted
Schools: Physics and Astronomy
Publisher: Cornell University
Last Modified: 14 Feb 2024 15:18

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