Monday

We present a general method to accurately predict the non-linear matter power spectrum of general extensions to the vanilla LCDM model. This approach requires only a suite of relatively inexpensive LCDM N-body simulations with initial conditions suitably modified, which can then be used as a training set for an emulator. By rescaling the predictions of our emulator with analytical halo model reactions, we can compute accurate non-linear matter power spectra for a broad class of beyond-LCDM cosmologies. We demonstrate the power of this approach with theoretically motivated modified gravity and massive neutrino paradigms, as well as artificial models featuring arbitrary deviations from LCDM. In all cases the emulator can reproduce the matter power spectrum with errors at the level of 1% or better deep in the highly non-linear regime. This work represents a significant step forward to limiting our reliance on expensive simulations, and gives viable means to test the validity of the standard cosmological model in the non-linear regime with the next generation of large-scale structure surveys.