by
Yannick Mellier(Institut d'Astrophysique de Paris and Observatoire de Paris (LERMA))
→
Europe/Stockholm
FA32
FA32
Description
Gravitational deflection of light induced by large scale structures
(cosmic shear) of the Universe produces a coherent weak distortion field that can be detected by measuring the shapes of distant galaxies. The statistical properties of the weak distortion field depends on the expansion rate and the growth rate of structures in the Universe and can be interpreted in order to recover the dark matter power spectrum and its evolution with look-back time.
So, in principle cosmic shear can be used to derived properties of both the dark matter and of dark energy.
The Canada-France-Hawaii-Telescope Legacy Survey (CFHTLS) has been optimized to provide the best measures ever done of
cosmic shear signal on scale ranging between 1 arc-minute to several degrees.