  We investigate the performance of semi-analytical modelling of large-scale
structure in Galileon gravity cosmologies using results from N-body
simulations. We focus on the Cubic and Quartic Galileon models that provide a
reasonable fit to CMB, SNIa and BAO data. We demonstrate that the Sheth-Tormen
mass function and linear halo bias can be calibrated to provide a very good fit
to our simulation results. We also find that the halo concentration-mass
relation is well fitted by a power law. The nonlinear matter power spectrum
computed in the halo model approach is found to be inaccurate in the mildly
nonlinear regime, but captures reasonably well the effects of the Vainshtein
screening mechanism on small scales. In the Cubic model, the screening
mechanism hides essentially all of the effects of the fifth force inside
haloes. In the case of the Quartic model, the screening mechanism leaves behind
residual modifications to gravity, which make the effective gravitational
strength time-varying and smaller than the standard value. Compared to normal
gravity, this causes a deficiency of massive haloes and leads to a weaker
matter clustering on small scales. For both models, we show that there are
realistic halo occupation distributions of Luminous Red Galaxies that can match
both the observed large-scale clustering amplitude and the number density of
these galaxies.

Cosmology and Nongalactic Astrophysics