Hi-COLA: Horndeski Goes Non-linear

          @misc{ pirsa_PIRSA:24070031,
            doi = {10.48660/24070031},
            url = {https://pirsa.org/24070031},
            author = {Baker, Tessa},
            keywords = {Cosmology, Strong Gravity, Mathematical physics},
            language = {en},
            title = {Hi-COLA: Horndeski Goes Non-linear},
            publisher = {Perimeter Institute},
            year = {2024},
            month = {jul},
            note = {PIRSA:24070031 see, \url{https://pirsa.org}}
          }
          

Abstract

Simulating non-linear scales of structure formation is essential to make use of frontier data from Stage IV galaxy surveys. Performing these simulations in modified gravity theories introduces additional challenges, and further forces us to make choices about which theories we deem ‘worth’ the computational investment. Horndeski Gravity is very helpful in this regard, as it encompasses a large swathe of models of major interest. I’ll introduce Hi-COLA, a software suite which simulates large-scale structure formation in the class of luminal Horndeski theories. Hi-COLA was designed to be: i) flexible — it avoids hard-coded models and instead receives a user-specified Lagrangian; ii) consistent — the background expansion history, linear growth and nonlinear screening are solved consistently with one another; iii) efficient — using the COLA method, large sets of simulations can be generated at low cost. I’ll explain how Hi-COLA can be used to make robust predictions for scalar-tensor theories on nonlinear scales. If time permits, we’ll also dip a toe into constraining the Horndeski framework with gravitational waves.