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Related Experiment Video

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The Hubble Constant.

Neal Jackson1

  • 1Jodrell Bank Centre for Astrophysics School of Physics and Astronomy, University of Manchester, Turing Building, Manchester, M13 9PL UK.

Living Reviews in Relativity
|February 7, 2017
PubMed
Summary

Determining the Universe's expansion rate (Hubble constant) shows a mild discrepancy between object-based and cosmic microwave background measurements. Resolving this requires improving accuracy and understanding systematic errors.

Area of Science:

  • Cosmology
  • Astrophysics
  • Astronomy

Background:

  • The Hubble constant (H₀) defines the Universe's expansion rate and length scale.
  • Current measurements of H₀ exhibit a mild discrepancy between different methods.
  • Understanding this discrepancy is crucial for refining cosmological models.

Purpose of the Study:

  • To review the current state of Hubble constant determinations.
  • To highlight the discrepancy between object-based and cosmic microwave background measurements.
  • To discuss the implications for precision cosmology and potential new physics.

Main Methods:

  • Review of astrophysical object-based measurements (e.g., supernovae, Cepheids).
  • Analysis of cosmic microwave background (CMB) data and galaxy correlations.
Keywords:
CosmologyHubble constant

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  • Comparison of results from independent cosmological datasets.

    • Main Results:

    • Object-based methods suggest H₀ ≈ 72-74 km s⁻¹ Mpc⁻¹.
    • CMB-based measurements (e.g., Planck) suggest H₀ ≈ 67-68 km s⁻¹ Mpc⁻¹.
    • A persistent discrepancy exists, indicating accuracy challenges over precision.

    Conclusions:

    • The discrepancy in H₀ measurements may require re-evaluation of systematic errors.
    • Resolving the Hubble tension could necessitate new physics beyond the standard cosmological model.
    • Further investigation into measurement systematics and cosmological parameter assumptions is essential.