Speaker
Description
We present a realistic Markov-Chain Monte-Carlo (MCMC) forecast for the precision of neutrino mass and cosmological parameter measurements with a Euclid-like galaxy clustering survey. We use the most general perturbation theory model for the one-loop power galaxy spectrum and tree-level bispectrum. This model is based on cosmological perturbation theory and includes non-linear bias, redshhift space distortions, IR resummation for baryon acoustic oscillations and so-called UV counterterms. The latter encapsulate various effects of short-scale dynamics which cannot be modeled within perturbation theory, e.g. baryonic feedback and fingers-of-God. Our MCMC procedure computes the theoretical power spectra and bispectra for each set of sampled cosmological parameters and nuisance coefficients describing the non-linear effects. The second ingredient of our approach is the theoretical error covariance which captures uncertainties due to higher-order non-linearities omitted in our model. Having specified characteristics of the spectroscopic survey based on the latest models of the Euclid-like galaxy luminosity function, we generate and fit mock galaxy power spectrum and bispectrum datasets. Our results suggest that even under the most agnostic assumptions about non-linear bias and short-scale physics the Euclid alone will be able to measure the sum of neutrino masses with $1\text{-}\sigma$ error of 25 meV. When combined with the most recent Planck likelihood, this uncertainty decreases to 18 meV. Reducing the theoretical error on the bispectrum down to the two-loop level improves the bound to 14 meV.
