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 complimentary information on cosmological parameters when compared to 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 systematic 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 allow a determination of useful information related to astrophysics on how galaxies occupy dark matter halos.