Non-linear galaxy power spectrum and cosmological parameters

The galaxy power spectrum is now a well-known tool of precision cosmology. In addition to the overall shape, baryon oscillations and the small-scale suppression of power by massive neutrinos capture complementary information on cosmological parameters when compared with the angular power spectrum of cosmic microwave background anisotropies. We study both the real-space and redshift-space galaxy power spectra in the context of non-linear effects, and model them based on the halo approach to large-scale structure clustering. We consider potential systematics in the cosmological parameter determination when non-linear effects are ignored and the galaxy power spectrum is described with the linear power spectrum scaled by a constant bias factor. We suggest that significant improvements can be made when non-linear effects are taken into account as a power-law contribution with two additional parameters to be determined from the data. In addition to cosmological parameters through galaxy clustering, such an approach allows a determination of useful information related to astrophysics on how galaxies occupy dark matter haloes.