LiteBIRD science goals and forecasts: a full-sky measurement of gravitational lensing of the CMB

We explore the capability of measuring lensing signals in LiteBIRD full-sky polarization maps. With a 30 arcmin beam width and an impressively low polarization noise of 2.16 μK-arcmin,LiteBIRD will be able to measure the full-sky polarization of the cosmic microwave background (CMB) very precisely. This unique sensitivity also enables the reconstruction of a nearly full-sky lensing map using only polarization data, even considering its limited capability to capture small-scale CMB anisotropies. In this paper, we investigate the ability to construct a full-sky lensing measurement in the presence of Galactic foregrounds, finding that several possible biases from Galactic foregrounds should be negligible after component separation by harmonic-space internal linear combination. We find that the signal-to-noise ratio of the lensing is approximately 40 using only polarization data measured over 80% of the sky. This achievement is comparable to Planck's recent lensing measurement with both temperature and polarization and represents a four-fold improvement over Planck's polarization-only lensing measurement. The LiteBIRD lensing map will complement the Planck lensing map and provide several opportunities for cross-correlation science, especially in the northern hemisphere. @article{Lonappan_2024, doi = {10.1088/1475-7516/2024/06/009}, url = {https://dx.doi.org/10.1088/1475-7516/2024/06/009}, year = {2024}, month = {jun}, publisher = {IOP Publishing}, volume = {2024}, number = {06}, pages = {009}, author = {Lonappan, A.I. and Namikawa, T. and Piccirilli, G. and Diego-Palazuelos, P. and Ruiz-Granda, M. and Migliaccio, M. and Baccigalupi, C. and Bartolo, N. and Beck, D. and Benabed, K. and Challinor, A. and Errard, J. and Farrens, S. and Gruppuso, A. and Krachmalnicoff, N. and Martínez-González, E. and Pettorino, V. 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 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 Génova-Santos, R.T. 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 Macias-Perez, J. 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 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: a full-sky measurement of gravitational lensing of the CMB}, journal = {Journal of Cosmology and Astroparticle Physics}, abstract = {We explore the capability of measuring lensing signals in LiteBIRD full-sky polarization maps. With a 30 arcmin beam width and an impressively low polarization noise of 2.16 μK-arcmin, LiteBIRD will be able to measure the full-sky polarization of the cosmic microwave background (CMB) very precisely. This unique sensitivity also enables the reconstruction of a nearly full-sky lensing map using only polarization data, even considering its limited capability to capture small-scale CMB anisotropies. In this paper, we investigate the ability to construct a full-sky lensing measurement in the presence of Galactic foregrounds, finding that several possible biases from Galactic foregrounds should be negligible after component separation by harmonic-space internal linear combination. We find that the signal-to-noise ratio of the lensing is approximately 40 using only polarization data measured over 80% of the sky. This achievement is comparable to Planck's recent lensing measurement with both temperature and polarization and represents a four-fold improvement over Planck's polarization-only lensing measurement. The LiteBIRD lensing map will complement the Planck lensing map and provide several opportunities for cross-correlation science, especially in the northern hemisphere.} }