Pierre Fleury (IPhT/Saclay, Paris)
Cosmic shear with Einstein rings
Weak lensing has become a key probe of cosmology. Such measurements are currently performed from the observation of the apparent ellipticity of galaxies. In this talk, I will introduce a new technique based on the distortions of strong-lensing images -- notably Einstein rings -- which are able to probe the line-of-sight shear produced by the large-scale structure. Theoretical arguments will be followed by a proof of concept based on mock images generated with the lenstronomy software. This novel way of probing comic shear promises exciting synergies between weak and strong lensing observations, e.g. within the Euclid survey.