Institute for Advanced Study / Princeton University Joint Astrophysics Colloquium

I will present the cosmological weak lensing results from the Dark Energy Survey (DES) using its first three years of data, taken on the 4m Blanco telescope at CTIO. This analysis spans the full DES footprint, more than 4000 sq. deg. of sky, with the final lensing catalogue containing more than 100 million galaxies in riz photometric bands, constituting the most powerful weak lensing dataset to date. The comparison of DES cosmological constraints from the low-redshift Universe to those from the Cosmic Microwave Background provides an unprecedented test of the standard cosmological model, across cosmic time. I will mention the main challenges that our analysis is susceptible to, and summarise the approach taken to account for these, in order to deliver robust cosmological constraints. Finally, I’ll summarise new developments necessary to exploit the data from future lensing surveys, such as DES Legacy and Rubin Observatory.