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 ( CMB ) Planck surveyor .
We use angular clustering of galaxies for DES in 7 redshift shells up to z \sim 1.7 including cross-correlations between different redshift shells .
We study models with massless and massive neutrinos and three different dark energy models : \Lambda CDM ( w = -1 ) , wCDM ( constant w ) , and waCDM ( 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 _ { \nu } < 0.08 eV ( 95 % C.L . )
for a fiducial mass of \Sigma m _ { \nu } = 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 _ { \nu } < 0.10 eV .
For a wCDM model where galaxy bias evolves with redshift , the upper limit on the sum of neutrino masses increases to 0.19 eV .
DES will be able to place competitive upper limits on the sum of neutrino masses of 0.1-0.2 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 _ { \nu } 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 } = 0.35 and \Delta w _ { a } = 0.89 .