LiteBIRD Science Goals and Forecasts: A full-sky measurement of gravitational lensing of the CMB
Creators: name: Lonappan, A. I.
name: Namikawa, T.
name: Piccirilli, G.
name: Diego-Palazuelos, P.
name: Ruiz-Granda, M.
name: Migliaccio, M.
name: Baccigalupi, C.
name: Bartolo, N.
name: Beck, D.
name: Benabed, K.
name: Challinor, A.
name: Errard, J.
name: Farrens, S.
name: Gruppuso, A.
name: Krachmalnicoff, N.
name: Martínez-González, E.
name: Pettorino, V.
name: Sherwin, B.
name: Starck, J.
name: Vielva, P.
name: Akizawa, R.
name: Anand, A.
name: Aumont, J.
name: Aurlien, R.
name: Azzoni, S.
name: Ballardini, M.
name: Banday, A. J.
name: Barreiro, R. B.
name: Bersanelli, M.
name: Blinov, D.
name: Bortolami, M.
name: Brinckmann, T.
name: Calabrese, E.
name: Campeti, P.
name: Carones, A.
name: Carralot, F.
name: Casas, F. J.
name: Cheung, K.
name: Clermont, L.
name: Columbro, F.
name: Conenna, G.
name: Coppolecchia, A.
name: Cuttaia, F.
name: D'Alessandro, G.
name: de Bernardis, P.
name: De Petris, M.
name: Della Torre, S.
name: Di Giorgi, E.
name: Eriksen, H. K.
name: Finelli, F.
name: Franceschet, C.
name: Fuskeland, U.
name: Galloni, G.
name: Galloway, M.
name: Georges, M.
name: Gerbino, M.
name: Gervasi, M.
name: Génova-Santos, R. T.
name: Ghigna, T.
name: Giardiello, S.
name: Gimeno-Amo, C.
name: Gjerløw, E.
name: Hazumi, M.
name: Henrot-Versillé, S.
name: Hergt, L. T.
name: Hivon, E.
name: Kohri, K.
name: Komatsu, E.
name: Lamagna, L.
name: Lattanzi, M.
name: Leloup, C.
name: Lembo, M.
name: López-Caniego, M.
name: Luzzi, G.
name: Macias-Perez, J.
name: Maffei, B.
name: Masi, S.
name: Massa, M.
name: Matarrese, S.
name: Matsumura, T.
name: Micheli, S.
name: Moggi, A.
name: Monelli, M.
name: Montier, L.
name: Morgante, G.
name: Mot, B.
name: Mousset, L.
name: Nagata, R.
name: Natoli, P.
name: Novelli, A.
name: Obata, I.
name: Occhiuzzi, A.
name: Pagano, L.
name: Paiella, A.
name: Paoletti, D.
name: Pascual-Cisneros, G.
name: Pavlidou, V.
name: Piacentini, F.
name: Pinchera, M.
name: Pisano, G.
name: Polenta, G.
name: Puglisi, G.
name: Remazeilles, M.
name: Ritacco, A.
name: Rizzieri, A.
name: Sakurai, Y.
name: Scott, D.
name: Shiraishi, M.
name: Signorelli, G.
name: Stever, S. L.
name: Takase, Y.
name: Tanimura, H.
name: Tartari, A.
name: Tassis, K.
name: Terenzi, L.
name: Tristram, M.
name: Vacher, L.
name: van Tent, B.
name: Wehus, I. K.
name: Weymann-Despres, G.
name: Zannoni, M.
name: Zhou, Y.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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 $2.16\,μ$K-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 $90\%$ 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.