Testing gravity on cosmological scales with large scale structures

Abstract: Various cosmological observations indicate that the expansion of the Universe is accelerating. The presence of a dark energy could explain this acceleration but it also could be due to general relativity being incorrect at large scales. Various theories of modified gravity have been proposed to address this open problem. In this talk I will review some of these theories and will then focus on two phenomenological parametrisations of modified gravity. Cosmological observables such as the cosmic shear are great probes to test these deviations from GR. I will explain how we proceed and show preliminary constraints with recent dataset.