A Detailed Description of the CamSpec Likelihood Pipeline and a Reanalysis of the Planck High Frequency Maps (1910.00483v3)

Abstract: This paper presents a detailed description of the CamSpec likelihood which has been used to analyse Planck temperature and polarization maps of the cosmic microwave background since the first Planck data release. We have created a number of likelihoods using a range of Galactic sky masks and different methods of temperature foreground cleaning. Our most powerful likelihood uses 80 percent of the sky in temperature and polarization. Our results show that the six-parameter LCDM cosmology provides an excellent fit to the Planck data. There is no evidence for statistically significant internal tensions in the Planck TT, TE and EE spectra computed for different frequency combinations. We present evidence that the tendencies for the Planck temperature power spectra to favour a lensing amplitude A_L>1 and positive spatial curvature are caused by statistical fluctuations in the temperature power spectra. Using our statistically most powerful likelihood, we find that the A_L parameter differs from unity at no more than the 2.2 sigma level. We find no evidence for anomalous shifts in cosmological parameters with multipole range. In fact, we show that the combined TTTEEE likelihood over the restricted multipole range 2-800 gives cosmological parameters for the base LCDM cosmology that are very close to those derived from the full multipole range 2-2500. We present revised constraints on a few extensions of the base LCDM cosmology, focussing on the sum of neutrino masses, number of relativistic species and the tensor-scalar ratio. The results presented here show that the Planck data are remarkably consistent between detector-sets, frequencies and sky area. We find no evidence in our analysis that cosmological parameters determined from the CamSpec likelihood are affected to any significant degree by systematic errors in the Planck data (abridged).

• The paper develops a robust CamSpec likelihood pipeline to analyze TT, TE, and EE spectra from Planck’s high-frequency observations.
• It refines base ΛCDM parameters using an expanded 80% sky coverage while effectively mitigating experimental systematics.
• The study reassesses lensing amplitude and spatial curvature trends, offering improved constraints on extensions like neutrino masses and the tensor-scalar ratio.

An In-Depth Examination of the CamSpec Likelihood Pipeline and Planck High Frequency Maps

The research paper by G. Efstathiou and S. Gratton provides a thorough evaluation of the CamSpec likelihood methodology used to analyze the temperature and polarization maps derived from the Planck satellite's observations of the Cosmic Microwave Background (CMB). This paper consolidates insights from extensive data generated by Planck, focusing on developing an accurate likelihood model based on TT, TE, and EE spectra, which are instrumental in testing cosmological models.

The authors elucidate the intricacies of their pipeline, emphasizing three critical aspects: the CMB sky and associated foregrounds at Planck's high frequencies above 100 GHz, the consistency of Planck's temperature and polarization data, and the mitigation of experimental systematics affecting these datasets.

The novelty of this work lies in the creation of several likelihoods that leverage extensive sky coverage. For instance, their most robust likelihood utilizes 80% of the sky in both temperature and polarization at frequencies of 143 and 217 GHz. This approach results in increased effective sky coverage compared to the 2018 Planck data release. Through this methodology, the authors present empirically strong findings that corroborate the foundational six-parameter $\Lambda$CDM cosmology. There is a clear absence of statistically significant internal tensions within the Planck TT, TE, and EE spectra, irrespective of frequency combinations.

One of the paper’s noteworthy contributions is the refined parameters for the base $\Lambda$CDM model, which align consistently with prior reports by the Planck collaboration, though with narrowed statistical uncertainties. This refinement also reduces the residuals of the TT, TE, and EE spectra relative to the best-fit model. Particularly, the analysis addresses the previously observed tendencies in Planck's temperature power spectra, which favored a lensing amplitude $A_L>1$ and positive spatial curvature $\Omega_k < 0$. Such tendencies are attributed to statistical fluctuations in the power spectra within the multipole range of 800 to 1600, which are consistently repeatable across detectors and frequencies.

By synthesizing their most potent likelihood with low multipole Planck likelihoods for $\ell < 30$ from 2018, the authors demonstrate that the $A_L$ parameter deviation from unity is limited to a 2.2 $\sigma$ level, thereby providing a robust reassessment of cosmological parameters. Additionally, their findings present no evidence for anomalous parameter shifts over different multipole ranges. Analysis of the combined TTTEEE CamSpec likelihood over the restricted multipole range $2 \le \ell \le 800$ reveals parameter values for the base $\Lambda$CDM cosmology closely mirroring those derived from a broader multipole range of $2 \le \ell \le 2500$.

Furthermore, the paper offers revised constraints on extensions of the $\Lambda$CDM model, including the sum of neutrino masses, the number of relativistic species, and the tensor-scalar ratio. Overall, the consistency of data across various detectors, frequencies, and sky regions is affirmed, with no significant influence of systematic errors impacting the cosmological parameters when determined from the CamSpec likelihood.

The practical implications of this paper reinforce the reliability of the Planck dataset as a robust foundation for CMB research. Theoretically, the results enhance understanding of the $\Lambda$CDM paradigm, potentially guiding future cosmological inquiries. In terms of future developments, the continued scrutiny of fluctuations within specific multipole ranges may yield further insights, contributing to the precision of cosmological models. This work underscores the enduring value of the Planck data, providing a benchmark for subsequent analyses in the field of cosmology.