[en] This paper analyzes the behavior of a family of finite exact perturbations of Friedmann-Robertson-Walker cosmologies constructed with the inverse scattering technique of Belinskii and Zakharov (1978). The application of this method in a five-dimensional spacetime with a massless scalar field and a subsequent Kaluza-Klein dimensional reduction makes it possible to construct models with perfect fluid material content in four dimensions. The behavior of the energy momentum and Weyl tensors are studied as characterizations of the gravitational and material behaviors. The important case of solitonic perturbations on de Sitter backgrounds is also treated. 45 refs

[en] We analyse exact static solutions of the vacuum Einstein equation obtained from the Appell ring solution to the Laplace equation. We first perform a Newtonian analysis and show that the Appell solution may be interpreted as the field of a shell of infinite negative total mass bordered by a ring of infinite positive total mass. This situation can be reproduced in general relativity, but a different interpretation, not requiring the shell as a source, is also possible pasting two spacetimes through the ring. The superposition of a particle with an Appell ring is also considered and in this case the shell interpretation is found to be inconsistent. (author)

[en] A new renormalization procedure for the solutions of Einstein's field equations in d dimensions obtainable by the inverse scattering method (ISM) of Belinskii and Zakharov [Sov. Phys. JETP 48, 985 (1978)] is presented. It allows one to obtain families of diagonal metrics which, in addition to the solitonic parameters that characterize the ISM, depend on 2(d-3) extra arbitrary parameters. An example of cosmological relevance where the source is a massless scalar field in five dimensions is presented. It represents a general family of two-parameter four-dimensional metrics that for great times go into the perfect fluid Friedman--Robertson-Walker regime

[en] The inverse scattering generation technique is applied to perfect fluid cosmological seed solutions in the context of a five-dimensional Kaluza-Klein formalism. As an example, the authors present a two-soliton metric generated from a Friedmann-Robertson-Walker background with a perfect fluid, which follows a general gamma-law equation of state. The resulting solution becomes asymptotically the background for large times. (author)

[en] It is shown that the inhomogeneous generalization of the Ellis-MacCallum family of Bianchi cosmological models of Wainwright et al. was given in an incomplete chart. The behavior of these models on the boundary of the chart is studied. Singularities are found in some cases and the general completeness of the manifolds is discussed