A TEST OF COSMOLOGICAL MODELS USING HIGH-z MEASUREMENTS OF H(z)

Journal Article · Thu Oct 15 04:00:00 EDT 2015 · Astronomical Journal (Online)

DOI:https://doi.org/10.1088/0004-6256/150/4/119· OSTI ID:22520126

Melia, Fulvio ^[1]

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1. Department of Physics, The Applied Math Program, and Department of Astronomy, The University of Arizona, AZ 85721 (United States)

The recently constructed Hubble diagram using a combined sample of SNLS and SDSS-II SNe Ia, and an application of the Alcock–Paczyński (AP) test using model-independent Baryon Acoustic Oscillation (BAO) data, have suggested that the principal constraint underlying the cosmic expansion is the total equation-of-state of the cosmic fluid, rather than that of its dark energy. These studies have focused on the critical redshift range (0 ≲ z ≲ 2) within which the transition from decelerated to accelerated expansion is thought to have occurred, and they suggest that the cosmic fluid has zero active mass, consistent with a constant expansion rate. The evident impact of this conclusion on cosmological theory calls for an independent confirmation. In this paper, we carry out this crucial one-on-one comparison between the R{sub h} = ct universe (a Friedmann–Robertson–Walker cosmology with zero active mass) and wCDM/ΛCDM, using the latest high-z measurements of H(z). Whereas the SNe Ia yield the integrated luminosity distance, while the AP diagnostic tests the geometry of the universe, the Hubble parameter directly samples the expansion rate itself. We find that the model-independent cosmic chronometer data prefer R{sub h} = ct over wCDM/ΛCDM with a Bayes Information Criterion likelihood of ∼95% versus only ∼5%, in strong support of the earlier SNe Ia and AP results. This contrasts with a recent analysis of H(z) data based solely on BAO measurements which, however, strongly depend on the assumed cosmology. We discuss why the latter approach is inappropriate for model comparisons, and emphasize again the need for truly model-independent observations to be used in cosmological tests.

• OSTI ID: 22520126
• Journal Information: Astronomical Journal (Online), Journal Name: Astronomical Journal (Online) Journal Issue: 4 Vol. 150; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BARYONS
COMPARATIVE EVALUATIONS
COSMOLOGICAL CONSTANT
COSMOLOGICAL MODELS
COSMOLOGY
DIAGRAMS
DISTANCE
EQUATIONS OF STATE
GALAXIES
LIMITING VALUES
LUMINOSITY
MASS
NONLUMINOUS MATTER
OSCILLATIONS
RED SHIFT
UNIVERSE