Scalar-tensor extension of the $\Lambda$CDM model
Abstract
We construct a cosmological scalar-tensor-theory model in which the Brans-Dicke type scalar enters the effective (Jordan-frame) Hubble rate as a simple modification of the Hubble rate of the 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.
Cite
@article{arxiv.1607.03952,
title = {Scalar-tensor extension of the $\Lambda$CDM model},
author = {W. C. Algoner and H. E. S. Velten and W. Zimdahl},
journal= {arXiv preprint arXiv:1607.03952},
year = {2016}
}
Comments
26 pages, 17 figures, stability analysis added, accepted for publication in JCAP