Deconstructing the neutrino mass constraint from galaxy redshift surveys
  The total mass of neutrinos can be constrained in a number of ways using
galaxy redshift surveys. Massive neutrinos modify the expansion rate of the
Universe, which can be measured using baryon acoustic oscillations (BAOs) or
the Alcock-Paczynski (AP) test. Massive neutrinos also change the structure
growth rate and the amplitude of the matter power spectrum, which can be
measured using redshift-space distortions (RSD). We use the Fisher matrix
formalism to disentangle these information sources, to provide projected
neutrino mass constraints from each of these probes alone and to determine how
sensitive each is to the assumed cosmological model. We isolate the distinctive
effect of neutrino free-streaming on the matter power spectrum and structure
growth rate as a signal unique to massive neutrinos that can provide the most
robust constraints, which are relatively insensitive to extensions to the
cosmological model beyond $\Lambda$CDM. We also provide forecasted constraints
using all of the information contained in the observed galaxy power spectrum
combined, and show that these maximally optimistic constraints are primarily
limited by the accuracy to which the optical depth of the cosmic microwave
background, $\tau$, is known.
