  Combining measurements of the galaxy power spectrum and the cosmic microwave
background (CMB) is a powerful means of constraining the summed mass of
neutrino species sum(m_nu), but is subject to systematic uncertainties due to
non-linear structure formation, redshift-space distortions and galaxy bias. We
empirically test the robustness of neutrino mass results to these effects by
separately analyzing power spectra of red and blue galaxies from the Sloan
Digital Sky Survey (SDSS-II) Data Release 7 (DR7), combined with the CMB
five-year Wilkinson Microwave Anisotropy Probe (WMAP5) data. We consider
fitting for a range of maximum wavenumber k using twelve different galaxy bias
models. For example, using a new model based on perturbation theory and
including redshift space distortions (Saito et al. 2009), the all-galaxy power
spectrum combined with WMAP5 for a wavenumber range of k<0.2 Mpc/h yields 95%
CL sum(m_nu)<0.46 eV. The red and blue galaxy power spectra give 0.41 and 0.63
eV respectively for this model. Using mock catalogues, we find the expected
difference in these limits assuming a true neutrino mass of zero is 0.10 + or -
0.14 eV. Thus the difference of 0.22 eV between upper limits on neutrino mass
for red and blue galaxies is approximately 1 sigma from the expected value. We
find similar results for the other models and k ranges tested. This indicates
good agreement for current data but hints at possible issues for
next-generation surveys. Being able to perform such systematic tests is
advantageous, and future surveys would benefit by including broad galaxy
populations and luminosities that enable such a decomposition.
