Validating estimates of the growth rate of structure with modified
  gravity simulations
  We perform a validation of estimates of the growth rate of structure,
described by the parameter combination $f\sigma_8$, in modified gravity
cosmologies. We consider an analysis pipeline based on the redshift-space
distortion modelling of the clustering wedges statistic of the galaxy
correlation function and apply it to mock catalogues of $\Lambda{\rm CDM}$ and
the normal branch of DGP cosmologies. We employ a halo occupation distribution
approach to construct our mocks, which we ensure resemble the CMASS sample from
BOSS in terms of the total galaxy number density and large scale amplitude of
the power spectrum monopole. We show that the clustering wedges model
successfully recovers the true growth rate difference between DGP and
$\Lambda{\rm CDM}$, even for cases with over 40\% enhancement in $f\sigma_8$
compared to $\Lambda{\rm CDM}$. The unbiased performance of the clustering
wedges model allows us to use the growth rate values estimated from the BOSS
DR12 data to constrain the cross-over scale $r_c$ of DGP gravity to
$\left[r_cH_0\right]^{-1} < 0.97$ ($2\sigma$) or $r_c > 3090\ {\rm Mpc}/h$,
cutting into the interesting region of parameter space with $r_c \sim H_0^{-1}$
using constraints from the growth of structure alone.
