mochi_class: A tool to streamline cosmological analyses of Horndeski's gravity

          @misc{ pirsa_PIRSA:24070068,
            doi = {10.48660/24070068},
            url = {https://pirsa.org/24070068},
            author = {Cataneo, Matteo},
            keywords = {},
            language = {en},
            title = {mochi_class: A tool to streamline cosmological analyses of Horndeski{\textquoteright}s gravity},
            publisher = {Perimeter Institute},
            year = {2024},
            month = {jul},
            note = {PIRSA:24070068 see, \url{https://pirsa.org}}
          }
          

Abstract

I will introduce mochi_class, a refined version of the popular Einstein-Boltzmann solver hi_class optimised for calculations within Horndeski's gravity framework. Thanks to (i) a re-parametrisation of Horndeski functions, (ii) a numerically stable quasi-static approximation, and (iii) support for time-dependent inputs, mochi_class enhances hi_class capabilities and nicely complements other public Einstein-Boltzmann solvers. Additionally, I will present a non-parametric approach that, when integrated with Principal Component Analysis, can effectively reconstruct Horndeski functions from well-studied modified gravity models, extending the exploration of scalar-tensor theories beyond conventional parametrisations. I will conclude by highlighting practical applications where mochi_class can prove instrumental in analysing current and forthcoming large-scale structure data.