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.

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

References in corpus (7)

• Dynamics of dark energy
• Cosmological viability of f(R)-gravity as an ideal fluid and its compatibility with a matter dominated phase
• The (pseudo)issue of the conformal frame revisited
• Einstein and Jordan frames reconciled: a frame-invariant approach to scalar-tensor cosmology
• Viability of f(R) Theories with Additional Powers of Curvature
• 6+1 lessons from f(R) gravity
• The dynamical viability of scalar-tensor gravity theories

Cited by in corpus (2)

• Diagnostic of Horndeski Theories
• Matter Growth in Imperfect Fluid Cosmology