Detectability of cosmic topology in generalized Chaplygin gas models

¹ Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150, 22290-180 Rio de Janeiro – RJ, Brazil e-mail: [brunom;reboucas;martin]@cbpf.br
² Universidade Federal do Rio de Janeiro, Instituto de Física, CP 68528, 21945-972 Rio de Janeiro – RJ, Brazil
³ Observatório Nacional - MCT, Rua Gal. José Cristino, 77 20921-400, Rio de Janeiro – RJ, Brazil

Received: 17 April 2005
Accepted: 13 September 2005

Abstract

If the spatial section of the universe is multiply connected, repeated images or patterns are expected to be detected in observations. However, due to the finite distance to the last scattering surface, such repeated patterns could be unobservable. This raises the question of whether a given cosmic topology is detectable, depending on the values of the parameters of the cosmological model. We study how the detectability is affected by the choice of the model itself for the matter-energy content of the universe, focusing our attention on the generalized Chaplygin gas (GCG) model for dark matter and dark energy unification, and investigate how the detectability of cosmic topology depends on the GCG parameters. We determine to what extent a number of topologies is detectable for the current observational bounds on these parameters. It emerges from our results that the choice of the GCG as an alternative to the ΛCDM matter-energy content model has an impact on the detectability of cosmic topology. In particular more topologies become detectable for a certain range of the GCG parameters. We stress that the method described here can be applied to any model for the matter-energy content.