Quantifying the global parameter tensions between ACT, SPT and Planck

TL;DR

This paper quantifies the parameter tensions between ACT, SPT, and Planck CMB datasets, revealing tensions of around 2.4 to 2.8 sigma, and discusses implications for combining these datasets within the standard cosmological model.

Contribution

It provides a quantitative assessment of tensions between major CMB datasets using the suspiciousness statistic, highlighting potential issues in dataset combination.

Findings

ACT and Planck tension is 2.6σ

ACT and SPT tension is 2.4σ

Combined ACT+SPT and Planck tension is 2.8σ

Abstract

The overall cosmological parameter tension between the Atacama Cosmology Telescope 2020 (ACT) and Planck 2018 data within the concordance cosmological model is quantified using the suspiciousness statistic to be 2.6$\sigma$. Between ACT and the South Pole Telescope (SPT) we find a tension of 2.4$\sigma$, and 2.8$\sigma$ between ACT and Planck+SPT combined. While it is unclear whether the tension is caused by statistical fluctuations, systematic effects or new physics, caution should be exercised in combining these cosmic microwave background datasets in the context of the $\Lambda$CDM standard model of the universe.