DESI and other Dark Energy experiments in the era of neutrino mass measurements

Abstract

We present Fisher matrix projections for future cosmological parametermeasurements, including neutrino masses, Dark Energy, curvature, modifiedgravity, the inflationary perturbation spectrum, non-Gaussianity, and darkradiation. We focus on DESI and generally redshift surveys (BOSS, HETDEX,eBOSS, Euclid, and WFIRST), but also include CMB (Planck) and weakgravitational lensing (DES and LSST) constraints. The goal is to present aconsistent set of projections, for concrete experiments, which are otherwisescattered throughout many papers and proposals. We include neutrino mass as afree parameter in most projections, as it will inevitably be relevant — DESIand other experiments can measure the sum of neutrino masses to ∼ 0.02 eVor better, while the minimum possible sum is ∼ 0.06 eV.We note that constraints on Dark Energy are significantly degraded by thepresence of neutrino mass uncertainty, especially when using galaxy clusteringonly as a probe of the BAO distance scale (because this introduces additionaluncertainty in the background evolution after the CMB epoch). Using broadbandgalaxy powerbecomes relatively more powerful, and bigger gains are achieved by combininglensing survey constraints with redshift survey constraints.We do not try to be especiallyinnovative, e.g., with complex treatments of potential systematic errors —these projections are intended as a straightforward baseline for comparison tomore detailed analyses.