LiteBIRD Science Goals and Forecasts. $E$-mode Anomalies

Various so-called anomalies have been found in both the WMAP and Planck cosmic microwave background (CMB) temperature data that exert a mild tension against the highly successful best-fit 6 parameter cosmological model, potentially providing hints of new physics to be explored. That these are real features on the sky is uncontested. However, given their modest significance, whether they are indicative of true departures from the standard cosmology or simply statistical excursions, due to a mildly unusual configuration of temperature anisotropies on the sky which we refer to as the "fluke hypothesis", cannot be addressed further without new information. No theoretical model of primordial perturbations has to date been constructed that can explain all of the temperature anomalies. Therefore, we focus in this paper on testing the fluke hypothesis, based on the partial correlation between the temperature and $E$-mode CMB polarisation signal. In particular, we compare the properties of specific statistics in polarisation, built from unconstrained realisations of the $Λ$CDM cosmological model as might be observed by the LiteBIRD satellite, with those determined from constrained simulations, where the part of the $E$-mode anisotropy correlated with temperature is constrained by observations of the latter. Specifically, we use inpainted Planck 2018 SMICA temperature data to constrain the $E$-mode realisations. Subsequent analysis makes use of masks defined to minimise the impact of the inpainting procedure on the $E$-mode map statistics. We find that statistical assessments of the $E$-mode data alone do not provide any evidence for or against the fluke hypothesis. However, tests based on cross-statistical measures determined from temperature and $E$ modes can allow this hypothesis to be rejected with a moderate level of probability.

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ArXiv.org
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2025-08-22
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Scientific Computing and Data Management
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article
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LiteBIRD Science Goals and Forecasts. $E$-mode Anomalies

Y. Sakurai, M. Ballardini, Mario de Lucia, Erwan Allys et al.
ArXiv.org
Scientific Computing and Data Management
article

LiteBIRD Science Goals and Forecasts. $E$-mode Anomalies

Y. Sakurai, M. Ballardini, Mario de Lucia, Erwan Allys, P. Diego-Palazuelos, E. Hivon, M Remazeilles, L. T. Hergt, Maresuke Shiraishi, M. Monelli, C. Baccigalupi, L. Porcelli, Lionel Clermont, F. Cacciotti, H. K. Eriksen, T. Ghigna, C Franceschet, E. Di Giorgi, D. Paoletti, J. Sanghavi, K. Cheung, M. Gervasi, M. Ruiz-Granda, Sohini Basak, S Della Torre, A. Occhiuzzi, Abhishek Anand, L. Terenzi, G Polenta, F. J. Casas, Darren M. Scott, D. Blinov, P. Vielva, P. Campeti, E. de la Hoz, E Martinez-Gonzalez, G. Piccirilli, M. Lattanzi, G. Signorelli, A. Carones, S. Micheli, M. López-Caniego, G. Weymann-Despres, G Pascual-Cisneros, S. Masi, F Columbro, F. R. Bouchet, Nicola Bartolo, C. Chiocchetta, A. Gruppuso, Ippei Obata, T Namikawa, M. Migliaccio, T. Matsumura, M. Bortolami, Masoud Najaf Najafi, R. B. Barreiro, B. Van Tent, M. Galloway, A. Rizzieri, A Coppolecchia, Erminia Calabrese, M. Hazumi, S. Giardiello, F Piacentini, J. Aumont, Andrea Novelli, L. Vacher, Kiyotomo Ichiki, G. Galloni, Edward J. Wollack, N. Raffuzzi, T Brinckmann, C. Gimeno-Amo, D Adak, A Besnard, A.I. Lonappan, Kenjiro Kohri, R.T Genova-Santos, R. M. Sullivan, I.K. Wehus, S. Matarrese, M. Tristram, J. Macias-Perez, M Tomasi, Y Takase, G Morgante, G. Luzzi, L. Lamagna, F. Levrier, B. Jost, H. Ishino, L. Montier, C. Leloup, Yu-Feng Zhou, A. J. Banday, J.A Rubino-Martin, U. Fuskeland, P de Bernardis, M. Bersanelli, A. Paiella, F. Finelli, M Citran, V Maranchery
article en

Abstract

Various so-called anomalies have been found in both the WMAP and Planck cosmic microwave background (CMB) temperature data that exert a mild tension against the highly successful best-fit 6 parameter cosmological model, potentially providing hints of new physics to be explored. That these are real features on the sky is uncontested. However, given their modest significance, whether they are indicative of true departures from the standard cosmology or simply statistical excursions, due to a mildly unusual configuration of temperature anisotropies on the sky which we refer to as the "fluke hypothesis", cannot be addressed further without new information. No theoretical model of primordial perturbations has to date been constructed that can explain all of the temperature anomalies. Therefore, we focus in this paper on testing the fluke hypothesis, based on the partial correlation between the temperature and $E$-mode CMB polarisation signal. In particular, we compare the properties of specific statistics in polarisation, built from unconstrained realisations of the $Λ$CDM cosmological model as might be observed by the LiteBIRD satellite, with those determined from constrained simulations, where the part of the $E$-mode anisotropy correlated with temperature is constrained by observations of the latter. Specifically, we use inpainted Planck 2018 SMICA temperature data to constrain the $E$-mode realisations. Subsequent analysis makes use of masks defined to minimise the impact of the inpainting procedure on the $E$-mode map statistics. We find that statistical assessments of the $E$-mode data alone do not provide any evidence for or against the fluke hypothesis. However, tests based on cross-statistical measures determined from temperature and $E$ modes can allow this hypothesis to be rejected with a moderate level of probability.

ArXiv.org
Université Paris Cité (FR), Institut d'Astrophysique de Paris (FR), Laboratoire AstroParticule et Cosmologie (FR), École Normale Supérieure - PSL (FR), Institut d'Astrophysique Spatiale (FR), Laboratoire de Physique de l'Ecole Normale Supérieure (FR), Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (FR), Laboratoire de Physique Subatomique et de Cosmologie (FR), Institut de Recherche en Astrophysique et Planétologie (FR)
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Scientific Computing and Data Management
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