scholarly journals Remarks on generalized scalar-tensor models of dark energy

2009 ◽  
Vol 80 (6) ◽  
Author(s):  
M. Alimohammadi ◽  
H. Behnamian
Keyword(s):  
Dark Energy ◽  
Tensor Models

scholarly journals Scalar–tensor models of normal and phantom dark energy

2006 ◽  
Vol 2006 (09) ◽  
pp. 016-016 ◽  
Author(s):  
Radouane Gannouji ◽  
David Polarski ◽  
André Ranquet ◽  
Alexei A Starobinsky
Keyword(s):  
Dark Energy ◽  
Tensor Models ◽  
Phantom Dark Energy

scholarly journals A unifying description of dark energy

2014 ◽  
Vol 23 (13) ◽  
pp. 1443010 ◽  
Author(s):  
Jérôme Gleyzes ◽  
David Langlois ◽  
Filippo Vernizzi
Keyword(s):  
Dark Energy ◽  
Equations Of Motion ◽  
Theoretical Models ◽  
Vast Number ◽  
Novel Approach ◽  
Cosmological Observations ◽  
Tensor Models ◽  
General Action ◽  
Flrw Universe ◽  
Quadratic Order

We review and extend a novel approach that we recently introduced, to describe general dark energy or scalar-tensor models. Our approach relies on an Arnowitt-Deser-Misner (ADM) formulation based on the hypersurfaces where the underlying scalar field is uniform. The advantage of this approach is that it can describe in the same language and in a minimal way a vast number of existing models, such as quintessence, F(R) theories, scalar tensor theories, their Horndeski extensions and beyond. It also naturally includes Horava–Lifshitz theories. As summarized in this review, our approach provides a unified treatment of the linear cosmological perturbations about a Friedmann-Lemaître-Robertson-Walker (FLRW) universe, obtained by a systematic expansion of our general action up to quadratic order. This shows that the behavior of these linear perturbations is generically characterized by five time-dependent functions. We derive the full equations of motion in the Newtonian gauge. In the Horndeski case, we obtain the equation of state for dark energy perturbations in terms of these functions. Our unifying description thus provides the simplest and most systematic way to confront theoretical models with current and future cosmological observations.

scholarly journals TOWARDS A FUTURE SINGULARITY?

2004 ◽  
Vol 13 (10) ◽  
pp. 2267-2273 ◽  
Author(s):  
M. GASPERINI
Keyword(s):  
Dark Energy ◽  
Negative Pressure ◽  
Future Singularity ◽  
Energy Field ◽  
Test Particles ◽  
Tensor Models ◽  
The Future ◽  
Models Of Gravity

We discuss whether the future extrapolation of the present cosmological state may lead to a singularity even in case of "conventional" (negative) pressure of the dark energy field, namely w=p/ρ≥-1. The discussion is based on an often neglected aspect of scalar–tensor models of gravity: the fact that different test particles may follow the geodesics of different metric frames, and the need for a frame-independent regularization of curvature singularities.

scholarly journals Constraints on scalar-tensor models of dark energy from observational and local gravity tests

2008 ◽  
Vol 77 (10) ◽  
Author(s):  
Shinji Tsujikawa ◽  
Kotub Uddin ◽  
Shuntaro Mizuno ◽  
Reza Tavakol ◽  
Jun’ichi Yokoyama
Keyword(s):  
Dark Energy ◽  
Tensor Models ◽  
Local Gravity

Dark energy on firmer footing

Nature ◽  
2010 ◽  
Author(s):  
Eugenie Samuel Reich
Keyword(s):  
Dark Energy

Dark energy probe gets high praise

Nature ◽  
2007 ◽  
Author(s):  
Geoff Brumfiel
Keyword(s):  
Dark Energy
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