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