Effects of cosmological model assumptions on galaxy redshift survey
  measurements
  The clustering of galaxies observed in future redshift surveys will provide a
wealth of cosmological information. Matching the signal at different redshifts
constrains the dark energy driving the acceleration of the expansion of the
Universe. In tandem with these geometrical constraints, redshift-space
distortions (RSD) depend on the build up of large-scale structure. As pointed
out by many authors measurements of these effects are intrinsically coupled. We
investigate this link, and argue that it strongly depends on the cosmological
assumptions adopted when analysing data. Using representative assumptions for
the parameters of the Euclid survey in order to provide a baseline future
experiment, we show how the derived constraints change due to different model
assumptions. We argue that even the assumption of a Friedman-Robertson-Walker
(FRW) space-time is sufficient to reduce the importance of the coupling to a
significant degree. Taking this idea further, we consider how the data would
actually be analysed and argue that we should not expect to be able to
simultaneously constrain multiple deviations from the standard $\Lambda$CDM
model. We therefore consider different possible ways in which the Universe
could deviate from the $\Lambda$CDM model, and show how the coupling between
geometrical constraints and structure growth affects the measurement of such
deviations.
