Conservative estimates of the mass of the neutrino from cosmology

A range of experimental results point to the existence of a massive neutrino. The recent high precision measurements of the cosmic microwave background and the large scale surveys of galaxies can be used to place an upper bound on this mass. In this paper we perform a thorough analysis of all assumptions that go into obtaining a credible limit on Sigma m(v). In particular we explore the impact of extending parameter space beyond the current standard cosmological model, the importance of priors and the uncertainties due to biasing in large scale structure. We find that the mass constraints are independent of the choice of parametrization as well as the inclusion of spatial curvature. The results of including the possibility of dark energy and tensor perturbations are shown to depend critically on the datasets used. The difference between an upper bound of 2.2 eV, assuming generic initial conditions, and an upper bound of 0.63 eV, assuming adiabaticity and a galaxy bias of 1, demonstrate the dependence of such a constraint on the assumptions in the analysis.