LiteBIRD Science Goals and Forecasts: A full-sky measurement of gravitational lensing of the CMB

• Published in: arXiv.org 2023-12
• Main Authors: Lonappan, A I, Namikawa, T, Ruiz-Granda, M, Migliaccio, M, Baccigalupi, C, Bartolo, N, Beck, D, Benabed, K, Challinor, A, Errard, J, Farrens, S, Gruppuso, A, Martínez-González, E, Sherwin, B, Starck, J, Akizawa, R, Anand, A, Aumont, J, Aurlien, R, Azzoni, S, Bersanelli, M, Bortolami, M, Brinckmann, T, Calabrese, E, Campeti, P, Carralot, F, Casas, F J, Cheung, K, Clermont, L, Columbro, F, Conenna, G, Coppolecchia, A, Cuttaia, F, D'Alessandro, G, De Petris, M, S Della Torre, Eriksen, H K, Franceschet, C, Fuskeland, U, Galloway, M, Georges, M, Gerbino, M, Gervasi, M, Génova-Santos, R 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, Lembo, M, López-Caniego, M, Luzzi, G, Macias-Perez, J, Maffei, B, Masi, S, Massa, M, Matarrese, S, Matsumura, T, Micheli, S, Monelli, M, Morgante, G, Mot, B, Mousset, L, Nagata, R, Natoli, P, Novelli, A, Obata, I, 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, Scott, D, Shiraishi, M, Signorelli, G, Stever, S L, Takase, Y, Tanimura, H, Tartari, A, Tassis, K, Tristram, M, Vacher, L, B van Tent, Wehus, I K, Zhou, Y, the LiteBIRD Collaboration
• Format: Article
• Language: English
• Subjects: Cosmic microwave background; Cross correlation; Gravitational lenses; Northern Hemisphere; Polarization; Signal to noise ratio
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2312.05184

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 \(2.16\,\mu\)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.