Patterns in the weak shear 3-point correlation function

¹ Service de Physique Théorique, CEA/DSM/SPhT, Unité de recherche associée au CNRS, CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France
² Institut d'Astrophysique de Paris, 98 bis bd Arago, 75014 Paris, France
³ Canadian Institute for Theoretical Astrophysics, 60 St George Str., M5S 3H8, Toronto, Canada
⁴ LERMA, Observatoire de Paris, 61 avenue de l'Observatoire, 75014 Paris, France

Corresponding author: F. Bernardeau, fbernard@spht.saclay.cea.fr

Received: 3 January 2002
Accepted: 16 August 2002

Abstract

We explore the scale and angular dependence of the cosmic shear three-point correlation function. The shear field is found to have a much more complex three-point function than the convergence field, but it also exhibits specific motifs which show signatures of gravitational lensing. Exact shear patterns are inferred analytically for some geometrical shear triplets configurations, when simple interpretations can be derived. A more complete description of their geometrical properties is then carried out from ray-tracing numerical simulations and simple models. These patterns reveal typical features that can be utilized for non-Gaussian signal detection in cosmic shear surveys. We test the robustness of these properties against complex noise statistics and non-trivial survey topologies. From these conclusive checks, we predict that the VIRMOS-DESCART survey should allow a detection of a non-Gaussian signal with a comfortable significance for a low matter density Universe.