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Eppur \`e piatto? The cosmic chronometer take on spatial curvature and cosmic concordance

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arxiv 2011.11645 v2 pith:RIUSVRXU submitted 2020-11-23 astro-ph.CO gr-qc

classification astro-ph.COgr-qc
keywords planckuniversecosmicdataspatiallybreakcurvaturedataset
verification ladder T0 review T1 audit T2 compute T3 formal
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abstract

The question of whether Cosmic Microwave Background (CMB) temperature and polarization data from Planck favor a spatially closed Universe with curvature parameter $\Omega_K<0$ has been the subject of recent intense discussions. Attempts to break the geometrical degeneracy combining Planck data with external datasets such as Baryon Acoustic Oscillation (BAO) measurements all point towards a spatially flat Universe, at the cost of significant tensions with Planck, which make the resulting dataset combination problematic. Settling this issue requires identifying a dataset which can break the geometrical degeneracy while not incurring in these tensions. We argue that cosmic chronometers (CC), measurements of the expansion rate $H(z)$ from the relative ages of massive early-type passively evolving galaxies, are the dataset we are after. Furthermore, CC come with the additional advantage of being virtually free of cosmological model assumptions. Combining Planck 2018 CMB temperature and polarization data with the latest CC measurements, we break the geometrical degeneracy and find $\Omega_K=-0.0054 \pm 0.0055$, consistent with a spatially flat Universe and competitive with the Planck+BAO constraint. Our results are stable against minimal parameter space extensions and CC systematics, and we find no substantial tension between Planck and CC data within a non-flat Universe, making the resulting combination reliable. Our results allow us to assert with confidence that the Universe is spatially flat to the ${\cal O}(10^{-2})$ level, a finding which might possibly settle the ongoing spatial curvature debate, and lends even more support to the already very successful inflationary paradigm.

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Cited by 7 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. BAO miscalibration cannot rescue late-time solutions to the Hubble tension

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    Even after rescaling BAO data to prefer H0≈73 km/s/Mpc, none of six tested late-time dark-energy models can resolve the Hubble tension once unanchored SNeIa and CMB geometry are included.

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    Quasar, supernova, BAO, DES, and CMB data are jointly compatible only in an interacting dark-energy model, not in Lambda-CDM, wCDM, or CPL.

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    gr-qc 2026-01 conditional novelty 5.0 of 10

    Barrow holographic dark energy with the Granda-Oliveros cutoff fits current background data as well as ΛCDM and shows a weak AIC preference only for the Union3-based dataset combination.

  4. Model-independent late-universe measurements of $H_0$ and $\Omega_K$ with the parametrization based on cosmic age-improved inverse distance ladder

    astro-ph.CO 2025-10 conditional novelty 5.0 of 10

    A cosmic-age-based inverse distance ladder with DESI DR2, DESY5, SGL, CC and GRB data gives H0=71.59±0.94 km/s/Mpc and ΩK=0.001±0.038.

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    gr-qc 2025-06 conditional novelty 5.0 of 10

    Barrow and Tsallis holographic dark energy models fit DESI DR2 data but are disfavored by information criteria versus LambdaCDM and do not ease the Hubble tension.

  6. Observational constraints on the modified cosmology inspired by string T-duality

    gr-qc 2025-10 conditional novelty 4.0 of 10

    Late-time data bound the T-duality zero-point-length coupling to β ≲ 10^-3, leaving ΛCDM statistically equivalent.

  7. Bayesian and Machine-Learning Analyses of Nonminimal $f(Q)$ Gravity and $H_0$ Tension

    gr-qc 2025-11 reject novelty 3.0 of 10

    A nonminimal f(Q) gravity model fitted to CC, DESI BAO and three supernova samples gives H0 ≈ 68 km/s/Mpc, similar to ΛCDM, and is disfavored by BIC.

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