Model-Independent Measurements of Cosmic Expansion and Growth at z=0.57
Using the Anisotropic Clustering of CMASS Galaxies From the Sloan Digital Sky
Survey Data Release 9
We analyze the anisotropic two dimensional galaxy correlation function (2DCF)
of the CMASS galaxy sample from the Sloan Digital Sky Survey Data Release 9
(DR9) of the Baryon Oscillation Spectroscopic Survey (BOSS) data. Modeling the
2DCF fully including nonlinear effects and redshift space distortions (RSD) in
the scale range of 30 to 120 h^{-1}Mpc, we find H(0.57)r_s(z_d)/c=0.0444 +/-
0.0019, D_A(0.57)/r_s(z_d)=9.01 +/- 0.23, and f_g(0.57)\sigma_8(0.57)=0.474 +/-
0.075, where r_s(z_d) is the sound horizon at the drag epoch computed using a
simple integral, and f_g(z) is the growth rate at redshift z, and \sigma_8(z)
represents the matter power spectrum normalization on 8h^{-1}Mpc scale at z. We
find that the scales larger than 120 h^{-1}Mpc are dominated by noise in the
2DCF analysis, and that the inclusion of scales 30-40 h^{-1}Mpc significantly
tightens the RSD measurement. Our measurements are consistent with previous
results using the same data, but have significantly better precision since we
are using all the information from the 2DCF in the scale range of 30 to 120
h^{-1}Mpc. Our measurements have been marginalized over sufficiently wide
priors for the relevant parameters; they can be combined with other data to
probe dark energy and gravity.Comment: 8 pages, 4 figures. Slightly modified version, accepted by MNRA