Reinterpreting quintessential dark energy through averaged inhomogeneous cosmologies (2006)
Larena, Julien, Buchert, Thomas, Alimi, Jean-Michel
Regionally averaged relativistic cosmologies have recently been considered as a possible explanation for the apparent late time acceleration of the Universe. This contribution reports on a mean field...
Buchert, Thomas, Larena, Julien, Alimi, Jean-Michel
Spatially averaged inhomogeneous cosmologies in classical general relativity can be written in the form of effective Friedmann equations with sources that include backreaction terms. In this paper we...
Big Bang nucleosynthesis in scalar tensor gravity: the key problem of the $^7$Li abundance (2005)
Larena, Julien, Alimi, Jean-Michel, Serna, Arturo
Combined with other CMB experiments, the WMAP survey provides an accurate estimate of the baryon density of the Universe. In the framework of the standard Big Bang Nucleosynthesis (BBN), such a...
Non equilibrium thermodynamics and cosmological pancakes formation (1998)
Teyssier, Romain, Chieze, Jean-Pierre, Alimi, Jean-Michel
We investigate the influence of non equilibrium thermodynamics on cosmological structure formation. In this paper, we consider the collapse of planar perturbations usually called "Zel'dovich...
Non-linear dynamics and mass function of cosmic structures. II Numerical results (1998)
Audit, Edouard, Teyssier, Romain, Alimi, Jean-Michel
We compare the mass functions obtained analytically, in the framework of an extended Press & Schechter (PS) formalism, in a previous paper to the numerical mass functions obtained in N -- body...
Multi-phase Hydrodynamics and X-ray Clusters Formation (1997)
Teyssier, Romain, CHIEZE, Jean-Pierre, Alimi, Jean-Michel
We investigate the role of radiative cooling within the core of large X-ray clusters using multi-phase hydrodynamics. We developed for that purpose a spherically symmetric hydrodynamical code,...
Are Large X-ray Clusters at Thermal Equilibrium ? (1997)
Chieze, Jean-Pierre, Teyssier, Romain, Alimi, Jean-Michel
We simulate the formation of a large X-ray cluster using a fully 3D hydrodynamical code coupled to a Particle-Mesh scheme which models the dark matter component. We focus on a possible decoupling...
Upper limit to $\Omega_B$ in scalar-tensor gravity theories (1997)
Alimi, Jean-Michel, Serna, Arturo
In a previous paper (Serna & Alimi 1996), we have pointed out the existence of some particular scalar-tensor gravity theories able to relax the nucleosynthesis constraint on the cosmic baryonic...
Gas and Dark Matter Spherical Dynamics (1997)
CHIEZE, Jean-Pierre, Teyssier, Romain, Alimi, Jean-Michel
We investigate the formation of spherical cosmological structures following both dark matter and gas components. We focus on the dynamical aspect of the collapse assuming an adiabatic, $\gamma =...
Self Similar Spherical Collapse Revisited: a Comparison between Gas and Dark Matter Dynamics (1997)
Teyssier, Romain, CHIEZE, Jean-Pierre, Alimi, Jean-Michel
We reconsider the collapse of cosmic structures in an Einstein-de Sitter Universe, using the self similar initial conditions of Fillmore & Goldreich (1984). We first derive a new approximation to...
Non-linear Dynamics and Mass Function of Cosmic Structures: I Analytical Results (1997)
Audit, Edouard, Teyssier, Romain, Alimi, Jean-Michel
We investigate some modifications to the Press & Schechter (1974) (PS) prescription resulting from shear and tidal effects. These modifications rely on more realistic treatments of the collapse...
Gravitational Dynamics of Cold Matter using the Deformation Tensor (1996)
Audit, Edouard, Alimi, Jean-Michel
In this paper we present a new local Lagrangian approximation to the gravitational dynamics of cold matter. We describe the dynamics of a Lagrangian fluid element through only one quantity, the...
Serna, Arturo, Alimi, Jean-Michel, Chieze, Jean-Pierre
We present and test a general-purpose code, called PPASPH, for evolving self-gravitating fluids in astrophysics, both with and without a collisionless component. In PPASPH, hydrodynamical properties...
Scalar-Tensor Cosmological Models (1995)
Serna, Arturo, Alimi, Jean-Michel
We analyze the qualitative behaviors of scalar-tensor cosmologies with an arbitrary monotonic $\omega(\Phi)$ function. In particular, we are interested on scalar-tensor theories distinguishable at...
Constraints on the Scalar-Tensor theories of gravitation from Primordial Nucleosynthesis (1995)
Serna, Arturo, Alimi, Jean-Michel
We present a detailed calculation of the light element production in the framework of Scalar-Tensor (ST) theories of gravitation. The coupling function \omega has been described by an appropriate...
Thesis (doctoral)--Université Pierre et Marie Curie, 1987.