LiteBIRD science goals and forecasts: improving sensitivity to inflationary gravitational waves with multitracer delensing
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. @article{Namikawa_2024,
doi = {10.1088/1475-7516/2024/06/010},
url = {https://dx.doi.org/10.1088/1475-7516/2024/06/010},
year = {2024},
month = {jun},
publisher = {IOP Publishing},
volume = {2024},
number = {06},
pages = {010},
author = {Namikawa, T. and Lonappan, A.I. and Baccigalupi, C. and Bartolo, N. and Beck, D. and Benabed, K. and Challinor, A. and Diego-Palazuelos, P. and Errard, J. and Farrens, S. and Gruppuso, A. and Krachmalnicoff, N. and Migliaccio, M. and Martínez-González, E. and Pettorino, V. and Piccirilli, G. and Ruiz-Granda, M. and Sherwin, B. and Starck, J. and Vielva, P. and Akizawa, R. and Anand, A. and Aumont, J. and Aurlien, R. and Azzoni, S. and Ballardini, M. and Banday, A.J. and Barreiro, R.B. and Bersanelli, M. and Blinov, D. and Bortolami, M. and Brinckmann, T. and Calabrese, E. and Campeti, P. and Carones, A. and Carralot, F. and Casas, F.J. and Cheung, K. and Clermont, L. and Columbro, F. and Conenna, G. and Coppolecchia, A. and Cuttaia, F. and D'Alessandro, G. and de Bernardis, P. and de Haan, T. and De Petris, M. and Della Torre, S. and Di Giorgi, E. and Eriksen, H.K. and Finelli, F. and Franceschet, C. and Fuskeland, U. and Galloni, G. and Galloway, M. and Georges, M. and Gerbino, M. and Gervasi, M. and Ghigna, T. and Giardiello, S. and Gimeno-Amo, C. and Gjerløw, E. and Hazumi, M. and Henrot-Versillé, S. and Hergt, L.T. and Hivon, E. and Kohri, K. and Komatsu, E. and Lamagna, L. and Lattanzi, M. and Leloup, C. and Lembo, M. and López-Caniego, M. and Luzzi, G. and Maffei, B. and Masi, S. and Massa, M. and Matarrese, S. and Matsumura, T. and Micheli, S. and Moggi, A. and Monelli, M. and Montier, L. and Morgante, G. and Mot, B. and Mousset, L. and Nagata, R. and Natoli, P. and Novelli, A. and Obata, I. and Occhiuzzi, A. and Pagano, L. and Paiella, A. and Paoletti, D. and Pascual-Cisneros, G. and Pavlidou, V. and Piacentini, F. and Pinchera, M. and Pisano, G. and Polenta, G. and Puglisi, G. and Remazeilles, M. and Ritacco, A. and Rizzieri, A. and Rubino-Martin, J. and Sakurai, Y. and Scott, D. and Shiraishi, M. and Signorelli, G. and Stever, S.L. and Takase, Y. and Tanimura, H. and Tartari, A. and Tassis, K. and Terenzi, L. and Tristram, M. and Vacher, L. and van Tent, B. and Wehus, I.K. and Weymann-Despres, G. and Zannoni, M. and Zhou, Y. and The LiteBIRD collaboration},
title = {LiteBIRD science goals and forecasts: improving sensitivity to inflationary gravitational waves with multitracer delensing},
journal = {Journal of Cosmology and Astroparticle Physics},
abstract = {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.}
}