Fast and accurate predictions of the non-linear matter power spectrum for general models of Dark Energy and Modified Gravity

ABSTRACT We embed linear and non-linear parametrizations of beyond standard cosmological physics in the halo model reaction framework, providing a model-independent prescription for matter power spectrum. As an application, we focus on Horndeski theories, using Effective Field Theory Dark Energy (EFTofDE) to parametrize quasi-non-linear perturbations. In regime, investigate both parametrized post-Friedmann (nPPF) approach as well physically motivated approximate phenomenological based error function (Erf). compare approaches’ predictions spectrum exact solutions, state-of-the-art emulators, evolving dark energy scenario two well-studied modified gravity models, finding sub-per cent agreement Erf at z ≤ 1 k 5 h Mpc−1. This suggests only additional three free constants, above background theory parameters, are sufficient non-linear, non-standard cosmology scales down 3h Mpc−1 within $2{{\ \rm per\ cent}}$ accuracy. implement into ver.2.0 ReACT code: ACTio et ReACTio.