A comparison of the Rh = ct and ΛCDM cosmologies using the cosmic distance duality relation

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The cosmic distance duality (CDD) relation (based on the Etherington reciprocity theorem) plays a crucial role in awide assortment of cosmological measurements. Attempts at confirming it observationally have met with mixed results, though the general consensus appears to be that the data do support its existence in nature. A common limitation with past approaches has been their reliance on a specific cosmological model, or on measurements of the luminosity distance to Type Ia SNe, which introduces a dependence on the presumed cosmology in spite of beliefs to the contrary. Confirming that the CDD is actually realized in nature is crucial because its violation would require exotic new physics. In this paper, we study the CDD using the observed angular size of compact quasar cores and aGaussian Process reconstruction of the HII galaxy Hubble diagram - without pre-assuming any particular background cosmology. In so doing, we confirm at a very high level of confidence that the angular-diameter and luminosity distances do indeed satisfy the CDD. We then demonstrate the potential power of this result by utilizing it in a comparative test of two competing cosmological models - the Rh = ct universe and ΛCDM - and show that Rh = ct is favoured by the CDD data with a likelihood ~82.3 per cent compared with ~17.7 per cent for the standard model.

Original languageEnglish (US)
Pages (from-to)4855-4862
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Dec 1 2018


  • Cosmological parameters
  • Cosmology: observations
  • Cosmology: theory
  • Distance scale
  • Galaxies: active

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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