167 citations · 448 across the 34 of their papers we have counts for
27 papers · 1 filter
Is bouncing easier with a negative effective dark fluid density ?
Stéphane Fay
Assuming that a cosmological model can describe the whole Universe history, we look for the conditions of a cosmological bounce thus in agreement with late time observations. Our a…
periodic cosmology
Stephane Fay
We examine the possibility that Universe expansion be made of some expansions repeating periodically, separated by some inflation and radiation dominated phases. This so-cal…
Phase space of static wormholes sustained by an isotropic perfect fluid
Stephane Fay
A phase space is built that allows to study, classify and compare easily large classes of static spherically symmetric wormholes solutions, sustained by an isotropic perfect fluid…
A coupled vacuum energy model producing endless alternated phases of accelerated and decelerated expansion
Stephane Fay
We consider a flat Universe filled with a vacuum energy coupled to matter and radiation by respectively positive coupling functions and . We require that these functions…
Ten scenarios from early radiation to late time acceleration with a minimally coupled dark energy
Stephane Fay
We consider General Relativity with matter, radiation and a minimally coupled dark energy defined by an equation of state w. Using dynamical system method, we find the equilibrium…
From inflation to late time acceleration with a decaying vacuum coupled to radiation or matter
Stéphane Fay
We consider General Relativity with matter and radiation, one of these fluids being coupled to vacuum. We find that Universe dynamics starts by an inflation phase if the coupled fl…
Can f(R) Modified Gravity Theories Mimic a LCDM Cosmology?
S. Fay, S. Nesseris, L. Perivolaropoulos
We consider f(R) modified gravity theories in the metric variation formalism and attempt to reconstruct the function f(R) by demanding a background LCDM cosmology. In particular we…
Large-scale structure and the Cardassian fluid
Stephane Fay, Morad Amarzguioui
In this paper, we confront the predictions of the power law cardassian model for the baryon power spectrum with the observations of the SDSS galaxy survey. We show that they fit on…
Branes: cosmological surprise and observational deception
Stephane Fay
Using some supernovae and CMB data, we constrain the Cardassian, Randall-Sundrum, and Dvali-Gabadadze-Porrati brane-inspired cosmological models. We show that a transient accelerat…
Bianchi type IX asymptotical behaviours with a massive scalar field: chaos strikes back
Stephane Fay, Thierry Lehner
We use numerical integrations to study the asymptotical behaviour of a homogeneous but anisotropic Bianchi type IX model in General Relativity with a massive scalar field. As it is…
Isotropisation of flat homogeneous Bianchi type I model with a non minimally coupled and massive scalar field
Stephane Fay
In previous works, we studied the isotropisation of Bianchi class A models with a minimally coupled scalar field. In this paper, we extend these results to the case of a non minima…
Homogeneous cosmology dynamics revealed by Hamiltonian ADM formalism
Stephane Fay
We study the homogeneous but anisotropic cosmological models of Bianchi in presence of a massive scalar field using the ADM Hamiltonian formalism. We begin to describe the main ste…
Properties of homogeneous cosmologies in scalar tensor theories
Stephane Fay
We study the isotropisation of the homogeneous but anisotropic Bianchi class A models in presence of a minimally coupled and massive scalar field with or without a perfect fluid. T…
Isotropisation of Bianchi class A models with a minimally coupled scalar field and a perfect fluid
Stephane Fay
We look for the necessary conditions allowing the Universe isotropisation in presence of a minimally coupled and massive scalar field with a perfect fluid. We conclude that it aris…
Scalar fields properties for flat galactic rotation curves
Stephane Fay
The whole class of minimally coupled and massive scalar fields which may be responsible for flattening of galactic rotation curves is found. An interesting relation with a class of…
A reciprocal Wald theorem for varying gravitational function
Stephane Fay
We study when a cosmological constant is a natural issue if it is mimicked by the potential of a massive Hyperextended Scalar Tensor theory with a perfect fluid for Bianchi type I…
Isotropisation of Bianchi class A models with curvature for a minimally coupled scalar tensor theory
Stephane Fay
We look for necessary isotropisation conditions of Bianchi class models with curvature in presence of a massive and minimally coupled scalar field when a function of the…
Isotropisation of the minimally coupled scalar-tensor theory with a massive scalar field and a perfect fluid in the Bianchi type I model
Stephane Fay
We look for necessary conditions such that minimally coupled scalar-tensor theory with a massive scalar field and a perfect fluid in the Bianchi type I model isotropises. Then we d…
Isotropisation of Generalized Scalar-Tensor theory plus a massive scalar field in the Bianchi type I model
Stephane Fay
In this paper we study the isotropisation of a Generalized Scalar-Tensor theory with a massive scalar field. We find it depends on a condition on the Brans-Dicke coupling function…
Exact solutions of the Hyperextended Scalar Tensor theory with potential in the Bianchi type I model
Stephane Fay
The Hyperextended Scalar Tensor theory with a potential is defined by three free functions: the gravitational function, the Brans-Dicke coupling function and the potential. Startin…
Noether Symmetry of the Hyperextended Scalar Tensor theory for the FLRW models
Stephane Fay
We study in which conditions the Hyperextended Scalar Tensor theory in an FLRW background admits a Noether symmetry and derive the vectors field generating it.
Sufficient conditions for curvature invariants to avoid divergencies in Hyperextended Scalar Tensor theory for Bianchi models
Stephane Fay
We look for sufficient conditions such that the scalar curvature, Ricci and Kretchmann scalars be bounded in Hyperextended Scalar Tensor theory for Bianchi models. We find classes…
Dynamical study of the hyperextended scalar-tensor theory in the empty Bianchi type I model
Stephane Fay
The dynamics of the hyperextended scalar-tensor theory in the empty Bianchi type I model is investigated. We describe a method giving the sign of the first and second derivatives o…
Hamiltonian study of the Generalized scalar-tensor theory with potential in a Bianchi type I model
Stephane Fay
We study the generalized scalar tensor theory with a potential in the Bianchi type I model by using the ADM formalism. We examine the conditions for the Universe to be in expansion…