One of main results of the 2013 data release of the Planck Collaboration are the CMB lensing related products, namely the first map on the full sky of the matter fluctuations at high redshift and improved constraints on cosmological parameters.
The intervening structure between us and the last scattering surface are responsible for coherent arcminute scale deflections of the primary anisotropies of temperature, an effect known as CMB lensing. It is possible to use the statistical signature generated by CMB lensing to reconstruct the lensing potential, which is the projection on the sky of all the matter density fluctuations from today up to the last scattering surface. This lensing potential therefore constitutes the most complete information on the matter distribution at high redshift.
In this talk, I will explain how the lensing potential, a quantity related to the large-scale structure of the Universe, has been reconstructed from the observations of the anisotropies of temperature of the Cosmic Microwave Background (CMB). I will then present in details the Planck lensing map and describe its use for cosmological studies, from improved constraints on cosmological parameters to joint analysis with current and future large-scale structure surveys.