Chasing cosmic acceleration with galaxies: From the Dark Energy Survey to the Rubin Observatory

Abstract:  

The origin of cosmic acceleration remains an open question: is it caused by a dark energy and if so, what are its properties? Or is our theory of gravity incomplete on the largest scales? These questions have driven an ambitious effort from the cosmology community to develop wide galaxy surveys. I will first explain how galaxies are indeed a powerful way to test cosmology, focusing on the weak lensing effect. I will then present the newest results on our understanding of the Universe and dark energy from the completed Dark Energy Survey (DES), which produced the largest weak lensing catalog to date. The methods and results the DES collaboration has developed over the past decade set the scene for the new generation of galaxy surveys such as the LSST by the Vera C. Rubin Observatory. I will update on the status of the Rubin Observatory and end with the challenges we will need to solve to test dark energy and gravity with its future weak lensing measurements.