Letter to the Editor

Detection of non-Gaussian signatures in the VIRMOS-DESCART lensing survey^*

¹ Service de Physique Théorique, CE de Saclay, 91191 Gif-sur-Yvette Cedex, France
² Institut d'Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France
³ Observatoire de Paris, LERMA, 61 avenue de l'Observatoire, 75014 Paris, France
⁴ Canadian Institute for Theoretical Astrophysics, 60 St George St., Toronto, Ont. M5S 3H8, Canada

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

Received: 27 February 2002
Accepted: 14 May 2002

Abstract

We have detected non-Gaussian signatures in the VIRMOS-DESCART weak lensing survey from a measurement of the three-point shear correlation function, following the method developed by Bernardeau et al. (2002). We obtain a 2.4σ signal over four independent angular bins, or equivalently, a 4.9-σ confidence level detection with respect to measurements errors on scale of about 2 to 4 arcmin. The amplitude and the shape of the signal are consistent with theoretical expectations obtained from ray-tracing simulations. This result supports the idea that the measure corresponds to a cosmological signal due to the gravitational instability dynamics. Its properties could be used to put constraints on the cosmological parameters, in particular on the density parameter of the Universe, but the error level as well as the cosmic variance are still too large to permit secure conclusions.