Topological lens effects in universes with non-Euclidean compact spatial   sections
  Universe models with compact spatial sections smaller than the observable universe produce a topological lens effect. Given a catalog of cosmic sources, we estimate the number of topological images in locally hyperbolic and locally elliptic spaces, as a function of the cosmological parameters, of the volume of the spatial sections and of the catalog depth. Next we apply the crystallographic method, aimed to detect a topological signal in the 3D distance histogram between images, to compact hyperbolic models. Numerical calculations in the Weeks manifold allows us to check the absence of crystallographic signature of topology, due to the fact that the number of copies of the fundamental domain in the observable covering space is low and that the points are not moved the same distance by the holonomies of space. 
R. Lehoucq (1), Jean-Pierre Luminet (2), Jean-Philippe Uzan (3,2) ((1)   CE-Saclay/Service d'Astrophysique, (2) DARC, Observ...