Deconstructing neutrino mass constraints from galaxy redshift surveys.

The upper limit on the sum of neutrino masses is provided by cosmology. Massive neutrinos modify the expansion rate of the Universe and the growth of matter perturbations in ways that can be measured using galaxy redshift surveys. However, as we demonstrate in our work, the constraints extracted are heavily dependent on the cosmological model assumed. Most such constraints are presented in the context of a flat Universe with a cosmological constant, but are significantly degraded if changes in curvature or the nature of dark energy are allowed. We break down and analyse the various ways in which the neutrino mass can be probed using galaxy surveys (including DESI, PFS and Euclid) and how sensitive the constraints from various probes are to cosmological assumptions. Importantly, we identify a cosmology-independent method of constraining the neutrino mass from galaxy survey data.