Isotropization of generalized scalar-tensor theory plus a massive scalar field in the Bianchi type I model

Abstract

In this paper we study the isotropization of a generalized scalar-tensor theory with a massive scalar field. We find it depends on a condition on the Brans-Dicke coupling function and the potential, and show that asymptotically the metric functions always tend toward a power or exponential law of the proper time. These results generalize and unify those of de Sitter in the case of a cosmological constant and of Cooley and Kitada in the case of an exponential potential.

Isotropisation of flat homogeneous Bianchi type I model with a non minimally coupled and massive scalar field

“…Its barotropic index w φ tends to 2 3 2 − 1. These results include the ones got when there is no matter [18]. For sake of clarity, we chose to express the above (as well as below) limits for k → 0 and m k → 0 as some functions of e − and φ.…”

Bianchi type IX asymptotical behaviours with a massive scalar field: chaos strikes back

“…The third one has been studied in [18,19,20,21] from the Bianchi models isotropisation point of view. In [12], the case with U = m 2 φ 2 was studied.…”

Scalar fields properties for flat galactic rotation curves

“…The limit (18) is doubly important. Firstly, in (Fay 2001(Fay , 2003Fay & Luminet 2003) it has been shown that a necessary condition for isotropisation of Bianchi models was ψU 2 ψ ωU 2 → 2 , being a constant in a close interval depending on the presence of curvature and perfect fluid. Consequently, galactic scalar field properties for large r could match a cosmological scalar field present in the entire Universe which would allow for its isotropisation.…”

“…The part of the results concerning the convergence of ψU 2 ψ ωU 2 to a constant seems strangely correlated to isotropisation of homogeneous models which also needs this condition (Fay 2001(Fay , 2003Fay & Luminet 2003). It shows that the properties of a galactic scalar field allowing the flattening of rotation curves could match those of a cosmological scalar field favouring Universe isotropisation.…”

“…Unification theories and particularly supersymmetry predict the existence of scalar fields, which thus deserve be taken into account in cosmology. Most of time, only their cosmological consequences are analysed: quintessence phenomenon (Johri 2001;Sahni 2000), isotropisation (Fay 2001) or inflation for instance. However, they could also be present at galactic scale.…”