The evidence for a spatially flat Universe

By G. Efstathiou, Steven Gratton. 2020

162 citations recorded by the source corpus.

We revisit the observational constraints on spatial curvature following recent claims that the Planck data favour a closed Universe. We use a new and statistically powerful Planck likelihood to show that the Planck temperature and polarization spectra are consistent with a spatially flat Universe, though because of a geometrical degeneracy cosmic microwave background spectra on their own do not lead to tight constraints on the curvature density parameter Omega_K. When combined with other astrophysical data, particularly geometrical measurements of baryon acoustic oscillations, the Universe is constrained to be spatially flat to extremely high precision, with Omega_ K = 0.0004 +/-0.0018 in agreement with the 2018 results of the Planck team. In the context of inflationary cosmology, the observations offer strong support for models of inflation with a large number of e-foldings and disfavour models of incomplete inflation.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/70dc82634ad7d4f2187274383c6d5c7fd9a24098

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In Astronomy and Astrophysics

In Nuclear and High Energy Physics

G. Efstathiou

Citations in the corpus

The Atacama Cosmology Telescope: DR4 maps and cosmological parameters (2020, unknown): “[70, 71]); this is connected to the deviation from unity of the expected lensing signal (AL) and its significance is reduced with different sky fractions and Planck likelihood choices [72].”
To H0 or not to H0? (2021, methodology): “Despite the fact that the author is an unashamed Hubble tension skeptic (Efstathiou 2020), I will take the SH0ES results at face value in this paper and consider whether the Hubble tension can be resolved by modifications to the ΛCDM late time expansion history.”
A buyer’s guide to the Hubble constant (2021, unknown): “However, most other observational evidence points to a flat universe (for example galaxy survey data or gravitational lensing of the CMB – see for example Efstathiou and Gratton 2020).”