Accurate halo-model matter power spectra with dark energy, massive neutrinos and modified gravitational forces

Abstract

We present an accurate non-linear matter power spectrum prediction scheme for\na variety of extensions to the standard cosmological paradigm, which uses the\ntuned halo model previously developed in Mead (2015b). We consider dark energy\nmodels that are both minimally and non-minimally coupled, massive neutrinos and\nmodified gravitational forces with chameleon and Vainshtein screening\nmechanisms. In all cases we compare halo-model power spectra to measurements\nfrom high-resolution simulations. We show that the tuned halo model method can\npredict the non-linear matter power spectrum measured from simulations of\nparameterised $w(a)$ dark energy models at the few per cent level for\n$k<10\\,h\\mathrm{Mpc}^{-1}$, and we present theoretically motivated extensions\nto cover non-minimally coupled scalar fields, massive neutrinos and Vainshtein\nscreened modified gravity models that result in few per cent accurate power\nspectra for $k<10\\,h\\mathrm{Mpc}^{-1}$. For chameleon screened models we\nachieve only 10 per cent accuracy for the same range of scales. Finally, we use\nour halo model to investigate degeneracies between different extensions to the\nstandard cosmological model, finding that the impact of baryonic feedback on\nthe non-linear matter power spectrum can be considered independently of\nmodified gravity or massive neutrino extensions. In contrast, considering the\nimpact of modified gravity and massive neutrinos independently results in\nbiased estimates of power at the level of 5 per cent at scales\n$k>0.5\\,h\\mathrm{Mpc}^{-1}$. An updated version of our publicly available\nHMcode can be found at https://github.com/alexander-mead/HMcode\n