Simultaneous constraints on the growth of structure and cosmic expansion from the multipole power spectra of the SDSS DR7 LRG sample

Abstract

The anisotropic galaxy clustering on large scales provides us with a unique\nopportunity to probe into the gravity theory through the redshift-space\ndistortions (RSDs) and the Alcock-Paczynski effect. Using the multipole power\nspectra up to hexadecapole (ell=4), of the Luminous Red Galaxy (LRG) sample in\nthe data release 7 (DR7) of the Sloan Digital Sky Survey II (SDSS-II), we\nobtain simultaneous constraints on the linear growth rate f, angular diameter\ndistance D_A, and Hubble parameter H at redshift z = 0.3. For this purpose, we\nfirst extensively examine the validity of a theoretical model for the\nnon-linear RSDs using mock subhalo catalogues from N-body simulations, which\nare constructed to match with the observed multipole power spectra. We show\nthat the input cosmological parameters of the simulations can be recovered well\nwithin the error bars by comparing the multipole power spectra of our\ntheoretical model and those of the mock subhalo catalogues. We also carefully\nexamine systematic uncertainties in our analysis by testing the dependence on\nprior assumption of the theoretical model and the range of wavenumbers to be\nused in the fitting. These investigations validate that the theoretical model\ncan be safely applied to the real data. Thus, our results from the SDSS DR7 LRG\nsample are robust including systematics of theoretical modeling; f(z = 0.3)\nsigma_8(z = 0.3) =0.49+-0.08(stat.)+-0.04(sys.), D_A (z = 0.3)\n=968+-42(stat.)+-17(sys.)[Mpc], H (z = 0.3)\n=81.7+-5.0(stat.)+-3.7(sys.)[km/s/Mpc]. We believe that our method to constrain\nthe cosmological parameters using subhaloes catalogues will be useful for more\nrefined samples like CMASS and LOWZ catalogues in the Baryon Oscillation\nSpectroscopic Survey in SDSS-III.\n