103 research outputs found
The 1+1+2 formalism for Scalar-Tensor gravity
We use the 1+1+2 covariant approach to clarify a number of aspects of
spherically symmetric solutions of non-minimally coupled scalar tensor
theories. Particular attention is focused on the extension of Birkhoff's
theorem and the nature of quasi-local horizons in this context.Comment: 27 pages, accepted versio
A new approach to reconstruction methods in gravity
We present a new approach of the reconstruction method based on the use of
the cosmic parameters instead of a time law for the scale factor. This allows
the derivation and analysis of a set of new non-trivial cosmological solutions
for -gravity. A number of simple examples are given.Comment: 5 pages, Revtex
Simultaneous expansion and rotation of shear-free universes in modified gravity
We show in a fully covariant way that, there exist a class of models
for which a shear-free, almost FLRW universe can expand and rotate at the same
time .Comment: 4 pages, no figures. Contribution submitted to the proceedings of the
Spanish Relativity Meeting ERE2011, September 2011, Madrid, Spai
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