Constraining neutrinos and dark energy with galaxy clustering in the dark energy survey

We determine the forecast errors on the absolute neutrino mass scale and the equation of state of dark energy by combining synthetic data from the Dark Energy Survey (DES) and the cosmic microwave background Planck surveyor. We use angular clustering of galaxies for DES in seven redshift shells up to z similar to 1.7 including cross-correlations between different redshift shells. We study models with massless and massive neutrinos and three different dark energy models:. cold dark matter (CDM) (w = -1), wCDM (constant w), and w(a)CDM [ evolving equation of state parameter w(a) = w(0) + w(a)(1-a)]. We include the impact of uncertainties in modeling galaxy bias using a constant and a redshift-evolving bias model. For the Lambda CDM model we obtain an upper limit for the sum of neutrino masses from DES + Planck of Sigma m(v) < 0.08 eV (95% C.L.) for a fiducial mass of Sigma m(v) = 0.047 eV, with a 1 sigma error of 0.02 eV, assuming perfect knowledge of galaxy bias. For the wCDM model the limit is Sigma m(v) < 0.10 eV. For a wCDM model where galaxy bias evolves with redshift, the upper limit on the sum of neutrino masses increases to 0.29 eV. DES will be able to place competitive upper limits on the sum of neutrino masses of 0.1-0.3 eV and could therefore strongly constrain the inverted mass hierarchy of neutrinos. In a wCDM model the 1 sigma error on constant w is Delta w = 0.03 from DES galaxy clustering and Planck. Allowing Sigma m(v) as a free parameter increases the error on w by a factor of 2, with Delta w = 0.06. In a waCDM model, in which the dark energy equation of state varies with time, the errors are Delta w(0) = 0.2 and Delta w(a) = 0.42. Including neutrinos and redshift-dependent galaxy bias increases the errors to Delta w(0) = 0.39 and Delta w(a) = 0.99.