Non-linear structure formation in modified gravity

          @misc{ pirsa_PIRSA:10040095,
            doi = {10.48660/10040095},
            url = {https://pirsa.org/10040095},
            author = {Schmidt, Fabian},
            keywords = {Cosmology},
            language = {en},
            title = {Non-linear structure formation in modified gravity},
            publisher = {Perimeter Institute},
            year = {2010},
            month = {apr},
            note = {PIRSA:10040095 see, \url{https://pirsa.org}}
          }
          

Abstract

Instead of adding another dark component to the energy budget of the Universe, one can ask whether the observed accelerated expansion might in fact be due to the behavior of gravity itself on the largest scales. In this talk I will focus on two popular modified gravity theories which realize this scenario: f(R) gravity and the DGP model. While these models yield an accelerated expansion, they also affect the formation of structure on much smaller scales. We have studied this with cosmological N-body simulations which consistently solve for the modified gravitational force. I will discuss the effects of modified gravity on dark matter halo properties as well as cosmological observables. For f(R) gravity, our first simulation-calibrated constraints from the observed abundance of massive clusters improve on previous constraints from the CMB and ISW by a factor of ~1000. This exemplifies the sensitivity of cosmological observables in the non-linear regime as probes of gravity.