BeyondPlanck I. Global Bayesian analysis of the Planck Low Frequency Instrument data

Abstract

We describe the BeyondPlanck project in terms of motivation, methodology and main products, and provide a guide to a set of companion papers that describe each result in fuller detail. We implement a complete end-to-end Bayesian analysis framework for the Planck LFI observations. The primary product is a full joint posterior distribution $P(\omega |d)$, where $\omega$ represents the set of all free instrumental, astrophysical, and cosmological parameters. Notable advantages of this approach are seamless end-to-end propagation of uncertainties; accurate modeling of both astrophysical and instrumental effects in the most natural basis for each uncertain quantity; optimized computational costs with little or no need for intermediate human interaction between various analysis steps; and a complete overview of the entire analysis process within one single framework. We focus in particular on low-$\ell$ CMB polarization reconstruction with Planck LFI. We identify several important new effects that have not been accounted for in previous pipelines, including gain over-smoothing and time-variable and non-$1/f$ correlated noise in the 30 and 44 GHz channels. We find that all results are consistent with the $\Lambda$CDM model, and we constrain the reionization optical depth to $\tau =0.066\pm 0.013$, with a low-resolution ${\chi }^2$ probability-to-exceed of 32%. This uncertainty is about 30% larger than the official pipelines, arising from taking into account a more complete instrumental model. The marginal CMB Solar dipole amplitude is $3362.7\pm 1.4\mu \mathrm{K}$, where the error bar is derived directly from the posterior distribution without the need of any ad-hoc instrumental corrections. We are currently not aware of any significant unmodelled systematic effects remaining in the Planck LFI data, and, for the first time, the 44 GHz channel is fully exploited. (Abridged.)

61 pages, 31 figures, submitted to A&A. Major revision: Previously reported unresolved effects are now understood and mitigated. This paper version concludes the BeyondPlanck project. All BeyondPlanck products and software are available at https://cosmoglobe.uio.no

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• Making sky maps from Planck data
• On the proper kinetic quadrupole CMB removal and the quadrupole anomalies
• Maximum likelihood, parametric component separation and CMB B-mode detection in suborbital experiments
• BeyondPlanck III. Commander3
• Making Maps from Planck LFI 30GHz Data
• Planck-LFI radiometers' spectral response
• BeyondPlanck XIII. Intensity foreground sampling, degeneracies, and priors
• BeyondPlanck VII. Bayesian estimation of gain and absolute calibration for CMB experiments
• BeyondPlanck X. Bandpass and beam leakage corrections
• BeyondPlanck XI. Bayesian CMB analysis with sample-based end-to-end error propagation
• From BeyondPlanck to Cosmoglobe: Preliminary $WMAP$ $Q$-band analysis
• BeyondPlanck XII. Cosmological parameter constraints with end-to-end error propagation
• BeyondPlanck VI. Noise characterization and modelling
• Improved large scales interstellar dust foreground model and CMB solar dipole measurement
• Cosmoglobe: Simulating zodiacal emission with ZodiPy
• BeyondPlanck X. Planck LFI frequency maps with sample-based error propagation
• BeyondPlanck VIII. Efficient Sidelobe Convolution and Correction through Spin Harmonics
• BeyondPlanck IV. On end-to-end simulations in CMB analysis -- Bayesian versus frequentist statistics
• BeyondPlanck II. CMB map-making through Gibbs sampling
• BeyondPlanck V. Minimal ADC Corrections for Planck LFI

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• BeyondPlanck III. Commander3
• High $H_0$ Values from CMB E-mode Data: A Clue for Resolving the Hubble Tension?
• Dispu$\tau$able: the high cost of a low optical depth
• BeyondPlanck VII. Bayesian estimation of gain and absolute calibration for CMB experiments
• BeyondPlanck X. Bandpass and beam leakage corrections
• BeyondPlanck XII. Cosmological parameter constraints with end-to-end error propagation
• Cosmoglobe DR1 results. I. Improved Wilkinson Microwave Anisotropy Probe maps through Bayesian end-to-end analysis
• BeyondPlanck XI. Bayesian CMB analysis with sample-based end-to-end error propagation
• BeyondPlanck VI. Noise characterization and modelling
• BeyondPlanck X. Planck LFI frequency maps with sample-based error propagation
• BeyondPlanck VIII. Efficient Sidelobe Convolution and Correction through Spin Harmonics
• Cosmic dipole tensions: confronting the cosmic microwave background with infrared and radio populations of cosmological sources
• BeyondPlanck IV. On end-to-end simulations in CMB analysis -- Bayesian versus frequentist statistics
• A Differentiable, End-to-End Forward Model for 21 cm Cosmology: Estimating the Foreground, Instrument, and Signal Joint Posterior
• BeyondPlanck II. CMB map-making through Gibbs sampling
• Bayesian evidence for flux scale errors in Galactic synchrotron maps
• BeyondPlanck V. Minimal ADC Corrections for Planck LFI
• Cosmoglobe: Towards end-to-end CMB cosmological parameter estimation without likelihood approximations
• Optimal bolometer transfer function deconvolution for CMB experiments through maximum likelihood mapmaking