There is a well known degeneracy between the enhancement of the growth of large-scale structure produced by modified gravity models and the suppression due to the free-streaming of massive neutrinos at late times. This makes the matter power-spectrum alone a poor probe to distinguish between modified gravity and the concordance ΛCDM model when neutrino masses are not strongly constrained.
In this talk, I will examine the potential of using redshift-space distortions (RSD) to break this degeneracy when the modification to gravity is scale-dependent in the form of Hu-Sawicki f(R). I will discuss our findings that if the linear growth rate can be recovered from the RSD signal, the degeneracy can be broken at the level of the dark matter field. However, this requires accurate modelling of the non-linearities in the RSD signal, and I will also introduce an extension of the standard perturbation theory-based model for non-linear RSD that includes both Hu-Sawicki f(R) modified gravity and massive neutrinos. Finally, I shall examine how we intend to develop our method to deal with biased tracers of the underlying dark matter in order to bring us closer to applying this analysis to galaxy clustering data.