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Scalar-tensor theories constraints from dark energy

Objective

The recent acceleration of our Universe expansion could be due to a dark energy having the form of a quintessent scalar field. Most of time, quintessent models considered in the literature are defined by a minimally coupled and massive scalar field with a perfect fluid. We propose to go beyond this physical framework by considering some non-minimally coupled scalar fields with a dissipative fluid, a Chaplygin gas or taking into acdbunt the presence of branes. For each of these models, we will calculate the d ark energy equation of state, the red shifts corresponding to the times when it dominates the matter and when the expansion begins to accelerate as well as its density parameter, the luminosity distance and the effects of curvature on these quantities.

These theoretical predictions will lie compared to the ones of the usual flat model with cosmological constant which is today one of the favourite dark energy model and we will look for how the current (WMAP, Supernovae Cosmology Project) and future (SNAP, PLA NCK) observations can help us to constrain these models in the geometrical framework of the isotropie and homogeneous cosmologies. The models in agreement with the observations will be then compared between them to detect degeneracy phenomena and we will propose some solutions to raise them such as new kinds of observations. The Astronomy group at Queen Mary University already has a strong interest on dark energy moje is and brane theories and is ideally located at the centre of one of the most active Europe areas in cosmology.

In what relates to me, I study the scalar-tensor theories since more than 6 years using some techniques and models that have been developed by its members. Among others my results led me to the idea that dark energy could be a natura l outcome of the homogeneous cosmological models isotropisation in presence of scalar fields.scalar fields with a dissipative fluid, a Chaplygin gas or taking into acdbunt the presence ofbranes. For each of these models, we will calculate the d ark energy equation of state, the redshifts corresponding to the times when it dominates the matter and when the expansion begins to accelerate as well as its density parameter, the luminosity distance and the effects of cThe recent acceleration of our Universe expansion could be due to a dark energy having the form of a quintessent scalar field. Most of time, quintessent models considered in the literature are defined by a minimally coupled and massive scalar field with a perfect fluid. We propose to go beyond this physical framework by considering some non-minimally coupled scalar fields with a dissipative fluid, a Chaplygin gas or taking into acdbunt the presence of branes. For each of these models, we will calculate the d ark energy equation of state, the red shifts corresponding to the times when it dominates the matter and when the expansion begins to accelerate as well as its density parameter, the luminosity distance and the effects of curvature on these quantities.

These theoretical predictions will lie compared to the ones of the usual flat model with cosmological constant which is today one of the favourite dark energy model and we will look for how the current (WMAP, Supernovae Cosmology Project) and future (SNAP, PLA NCK) observations can help us to constrain these models in the geometrical framework of the isotropie and homogeneous cosmologies. The models in agreement with the observations will be then compared between them to detect degeneracy phenomena and we will propose some solutions to raise them such as new kinds of observations. The Astronomy group at Queen Mary University already has a strong interest on dark energy moje is and brane theories and is ideally located at the centre of one of the most active Europe areas in cosmology.

In what relates to me, I study the scalar-tensor theories since more than 6 years using some techniques and models that have been developed by its members. Among others my results led me to the idea that dark energy could be a natura l outcome of the homogeneous cosmological models isotropisation in presence of scalar fields.

Call for proposal

FP6-2002-MOBILITY-5
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Coordinator

QUEEN MARY AND WESTFIELD COLLEGE
Address
Mile End Road
London
United Kingdom