Testing the halo model against the SDSS photometric survey

ABSTRACT We present halo model predictions for the expected angular clustering and associated errors from the completed Sloan Digital Sky Survey (SDSS) photometric galaxy sample. These results are used to constrain halo model parameters under the assumption of a fixed ΛCDM cosmology using standard Fisher matrix techniques. Given the ability of the five‐colour SDSS photometry to separate galaxies into subpopulations by intrinsic colour, we also use extensions of the standard halo model formalism to calculate the expected clustering of red and blue galaxy subpopulations as a further test of the galaxy evolution included in the semi‐analytical methods for populating dark matter haloes with galaxies. The extremely small sample variance and Poisson errors from the completed SDSS should result in very impressive constraints (∼1–10 per cent) on the halo model parameters for a simple magnitude‐limited sample and should provide an extremely useful check on the behaviour of current and future N ‐body simulations and semi‐analytical techniques. We also show that similar constraints are possible using a narrow selection function, as would be possible using photometric redshifts, without making linear assumptions regarding the evolution of the underlying power spectra. In both cases, we explore the effects of uncertainty in the selection function on the resulting constraints and the degeneracies between various combinations of parameters.