Testing one-loop galaxy bias
Andrea Pezzotta
Observations of different types of galaxies, or clusters of galaxies, has led to realisation that these objects are biased tracers of the dark matter density field, and that a consistent theory of galaxy bias must be developed in order to fully exploit the cosmological constraining power of galaxy redshift surveys. From this point of view, perturbative approaches are a standard way of describing the galaxy density field as a function of the underlying matter distribution. In this talk we are going to present results from the testing of different modelling assumptions of one-loop galaxy bias, and their impact on the recovery of cosmological parameters. We investigate the relevance of allowing for either short range non-locality or scale-dependent stochasticity by fitting the real-space galaxy auto power spectrum and the combination between galaxy-galaxy and galaxy-matter power spectrum. From a comparison between the goodness-of-fit, unbiasedness of cosmological parameters, and merit of the model, we find that a simple four-parameter model (linear, quadratic, cubic non-local bias, and constant shot-noise) with fixed quadratic tidal bias provides a robust modelling choice for the auto power spectrum of the three galaxy samples, up to a maximum scale of 0.3 h/Mpc and for an effective volume of (6 Gpc/h)^3. On the contrary we find that the combined statistics seems to favour the presence of either higher derivatives or scale-dependent shot-noise, with the latter providing the most accurate and stable results.