Complete density perturbations in the Jordan-Fierz-Brans-Dicke theory
Abstract
In the context of scalar-tensor theories we study the evolution of the density contrast for Jordan-Fierz-Brans-Dicke theories in a Friedmann-Lemaitre-Robertson-Walker Universe. Calculations are performed in the Einstein Frame with the cosmological background described as Lambda-Cold Dark Matter (Lambda-CDM) and supplemented by a Jordan-Fierz-Brans-Dicke field. By using a completely general procedure valid for all scalar-tensor theories, we obtain the exact fourth-order differential equation for the density contrast evolution in modes of arbitrary size. In the case of sub-Hubble modes, the expression reduces to a simpler but still fourth-order equation that is then compared with the standard (quasistatic) approximation. Differences with respect to the evolution as predicted by the standard Concordance Lambda-CDM model are observed depending on the value of the coupling.
Keywords
Cite
@article{arxiv.1307.0521,
title = {Complete density perturbations in the Jordan-Fierz-Brans-Dicke theory},
author = {J. A. R. Cembranos and A. de la Cruz Dombriz and L. Olano Garcia},
journal= {arXiv preprint arXiv:1307.0521},
year = {2013}
}
Comments
15 pages, 6 figures, 1 appendix