Forecasting neutrino masses from galaxy clustering in the Dark Energy Survey combined with the Planck measurements

We study the prospects for detecting neutrino masses from the galaxy angular power spectrum in photometric redshift shells of the Dark Energy Survey (DES) over a volume of similar to 20 h-3 Gpc3, combined with the cosmic microwave background (CMB) angular fluctuations expected to be measured from the Planck satellite. We find that for a Lambda cold dark matter concordance model with seven free parameters in addition to a fiducial neutrino mass of M-nu = 0.24 eV, we recover from DES and Planck the correct value with uncertainty of +/- 0.12 eV (95 per cent confidence level; CL), assuming perfect knowledge of the galaxy biasing. If the fiducial total mass is close to zero, then the upper limit is 0.11 eV (95 per cent CL). This upper limit from DES and Planck is over three times tighter than using Planck alone, as DES breaks the parameter degeneracies in a CMB-only analysis. The analysis utlilizes spherical harmonics up to 300, averaged in bin of 10 to mimic the DES sky coverage. The results are similar if we supplement DES bands (grizY) with the Visible and Infra-Red Survey Telescope for Astronomy Hemisphere Survey (VHS) near-infrared band (JHK). The result is robust to uncertainties in non-linear fluctuations and redshift distortions. However, the result is sensitive to the assumed galaxy biasing schemes and it requires accurate prior knowledge of the biasing. To summarize, if the total neutrino mass in nature is greater than 0.1 eV, we should be able to detect it with DES and Planck, a result with great importance to fundamental physics.