Which FLRW comoving 3-manifold is preferred observationally and theoretically?

The lack of structure greater than 10 Gpc/h in Wilkinson Microwave Anisotropy Probe (WMAP) observations of the cosmic microwave background (CMB) favours compact Friedmann-Lemaitre-Robertson-Walker (FLRW) models of the Universe. The present best candidates based on observations are the Poincare dodecahedral space S^3/I^* and the 3-torus T^3. The residual gravity effect favours the Poincare space, while a measure space argument where the density parameter is a derived parameter favours flat spaces almost surely.Comment: 3 pages, Twelfth Marcel Grossmann Meeting on General Relativity, ed. Thibault Damour, Robert T Jantzen, Remo Ruffini, Singapore: World Scientifi

A residual acceleration effect due to an inhomogeneity

The perturbed Friedmann-Lemaitre-Robertson-Walker models allow many different possibilities for the 3-manifold of the comoving spatial section of the Universe. It used to be thought that global properties of the spatial section, including the topology of the space, have no feedback effect on dynamics. However, an elementary, weak-limit calculation shows that in the presence of a density perturbation, a gravitational feedback effect that is algebraically similar to dark energy does exist. Moreover, the effect differs between different 3-spaces. Among the well-proportioned spaces, the effect disappears down to third order in several cases, and down to fifth order for the Poincare dodecahedral space S^3/I^*. The Poincare space, that which also is preferred in many observational analyses, is better-balanced than the other spaces.Comment: 6 pages, 1 figure, v1 submitted to Proceedings of the Invisible Universe International Conference, held in Paris, France, June 29-July 3, 2009 - after it is published, it will be found at http://proceedings.aip.org/proceedings

Observational Approaches to the Topology of the Universe

Many different and complementary strategies for translating the basic principle of multiple topological imaging into observational analysis are now available, both for three-dimensional and two-dimensional catalogues.Comment: very compact, (2 page) write-up of invited review for Marcel Grossmann IX Meeting in Roma, 1st page classifies and cites different observational strategies, 2nd page reference list includes many key 1999/2000 reference

WMAP First Year Sky Map: Hints of Poincare Dodecahedral Topology

Several analyses of the cosmic microwave background map made by the satellite WMAP suggest that the global shape of a spatial section of the Universe is that of a Poincare dodecahedral space. A summary of some of these analyses and a description of independent tests which should be able to either increase confidence in the hypothesis or else refute it to extremely high significance will be presented.Comment: v1 submitted to Proceedings of the Albert Einstein Century International Conference, held in Paris, France, July 18-22, 2005 - after it is published, it will be found at http://proceedings.aip.org/proceedings/, v2 has minor correction to one referenc