Conformal Transformations in Cosmology of Modified Gravity: the Covariant Approach Perspective

Details Conformal Transformations in Cosmology of Modified Gravity: the Covariant Approach Perspective Conformal Transformations in Cosmology of Modified Gravity: the Covariant Approach Perspective

2009-07-23

arxiv.org/abs/0907.3941v2

Astronomy and Astrophysics

Astrophysics

General Relativity and Quantum Cosmology

26 pages, 8 figures

Scientific paper

The 1+3 covariant approach and the covariant gauge-invariant approach to perturbations are used to analyze in depth conformal transformations in cosmology. Such techniques allow us to obtain very interesting insights on the physical content of these transformations, when applied to non-standard gravity. The results obtained lead to a number of general conclusions on the change of some key quantities describing any two conformally related cosmological models. In particular, it is shown that the physics in the Einstein frame has characteristics which are completely different from those in the Jordan frame. Even if some of the geometrical properties of the cosmology are preserved (homogeneous and isotropic Universes are mapped into homogeneous and isotropic universes), it can happen that decelerating cosmologies are mapped into accelerated ones. Differences become even more pronounced when first-order perturbations are considered: from the 1+3 equations it is seen that first-order vector and tensor perturbations are left unchanged in their structure by the conformal transformation, but this cannot be said of the scalar perturbations, which include the matter density fluctuations. Behavior in the two frames of the growth rate, as well as other evolutionary features, like the presence or absence of oscillations, etc., appear to be different too. The results obtained are then explicitly interpreted and verified with the help of some clarifying examples based on $f(R)$-gravity cosmologies.

Affiliated with

Also associated with

No associations

Rating

Conformal Transformations in Cosmology of Modified Gravity: the Covariant Approach Perspective does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Conformal Transformations in Cosmology of Modified Gravity: the Covariant Approach Perspective, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Conformal Transformations in Cosmology of Modified Gravity: the Covariant Approach Perspective will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-354224