Scalar-tensor extension of the $\Lambda$CDM model

Abstract

We construct a cosmological scalar-tensor-theory model in which the Brans-Dicke type scalar $\Phi$ enters the effective (Jordan-frame) Hubble rate as a simple modification of the Hubble rate of the $\Lambda$CDM model. This allows us to quantify differences between the background dynamics of scalar-tensor theories and general relativity (GR) in a transparent and observationally testable manner in terms of one single parameter. Problems of the mapping of the scalar-field degrees of freedom on an effective fluid description in a GR context are discused. Data from supernovae, the differential age of old galaxies and baryon acoustic oscillations are shown to strongly limit potential deviations from the standard model.

arXiv comment26 pages, 17 figures, stability analysis added, accepted for publication in JCAP

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Cited by in corpus (6)

• Imperfect fluid description of modified gravities
• Non-minimally coupled scalar field cosmology with torsion
• Diagnostic of Horndeski Theories
• Extended $\Lambda$CDM model
• Matter Growth in Imperfect Fluid Cosmology
• Matter growth in extended $\Lambda$CDM cosmology