The BACCO simulation project: exploiting the full power of large-scale structure for cosmology

We present the BACCO project, a simulation framework specially designed to provide highly-accurate predictions for the distribution of mass, galaxies, and gas as a function of cosmological parameters. In this paper, we describe our main suite of gravity-only simulations (L~ 2\, Gpc and 43203 particles) and present various validation tests. Using a cosmology-rescaling technique, we predict the non-linear mass power spectrum over the redshift range 0 < z < 1.5 and over scales 10⁻² < k/(\, h\, Mpc⁻¹) < 5 for 800 points in an eight-dimensional cosmological parameter space. For an efficient interpolation of the results, we build an emulator and compare its predictions against several widely-used methods. Over the whole range of scales considered, we expect our predictions to be accurate at the 2\ per\ cent level for parameters in the minimal Lambda cold dark matter model and to 3\ per\ cent when extended to dynamical dark energy and massive neutrinos. We make our emulator publicly available under http://www.dipc.org/bacco