BeyondPlanck XI. Bayesian CMB analysis with sample-based end-to-end error propagation

Abstract

We present posterior sample-based cosmic microwave background (CMB) constraints from Planck LFI and WMAP observations derived through global end-to-end Bayesian processing. We use these samples to study correlations between CMB, foreground, and instrumental parameters, and we identify a particularly strong degeneracy between CMB temperature fluctuations and free-free emission on intermediate angular scales, which is mitigated through model reduction, masking, and resampling. We compare our posterior-based CMB results with previous Planck products, and find generally good agreement, but with higher noise due to exclusion of HFI data. We find a best-fit CMB dipole amplitude of $3362.7\pm 1.4\mu K$, in excellent agreement with previous Planck results. The quoted uncertainty is derived directly from the sampled posterior distribution, and does not involve any ad hoc contribution for systematic effects. Similarly, we find a temperature quadrupole amplitude of ${\sigma }_2^{TT}=229\pm 97\mu K^2$, in good agreement with previous results in terms of the amplitude, but the uncertainty is an order of magnitude larger than the diagonal Fisher uncertainty. Relatedly, we find lower evidence for a possible alignment between $\ell =2$ and $\ell =3$ than previously reported due to a much larger scatter in the individual quadrupole coefficients, caused both by marginalizing over a more complete set of systematic effects, and by our more conservative analysis mask. For higher multipoles, we find that the angular temperature power spectrum is generally in good agreement with both Planck and WMAP. This is the first time the sample-based asymptotically exact Blackwell-Rao estimator has been successfully established for multipoles up to $\ell \le 600$, and it now accounts for the majority of the cosmologically important information. Cosmological parameter constraints are presented in a companion paper. (Abriged)

26 pages, 24 figures. Submitted to A&A. Part of the BeyondPlanck paper suite

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• BeyondPlanck X. Bandpass and beam leakage corrections
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• BeyondPlanck XII. Cosmological parameter constraints with end-to-end error propagation
• BeyondPlanck X. Planck LFI frequency maps with sample-based error propagation
• BeyondPlanck VIII. Efficient Sidelobe Convolution and Correction through Spin Harmonics
• BeyondPlanck V. Minimal ADC Corrections for Planck LFI

Cited by in corpus (10)

• BeyondPlanck III. Commander3
• Cosmoglobe DR1 results. II. Constraints on isotropic cosmic birefringence from reprocessed WMAP and Planck LFI data
• BeyondPlanck XIII. Intensity foreground sampling, degeneracies, and priors
• 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 X. Planck LFI frequency maps with sample-based error propagation
• Almanac: MCMC-based signal extraction of power spectra and maps on the sphere
• BeyondPlanck IV. On end-to-end simulations in CMB analysis -- Bayesian versus frequentist statistics
• BeyondPlanck V. Minimal ADC Corrections for Planck LFI