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![]() Our sample, which we denote MGS, covers 6,813 deg2 with an effective redshift zeff=0.15 and is described in our companion paper (Paper I), which concentrates on BAO measurements. Assuming a background ΛCDM cosmology and combining with current Baryon Acoustic Oscillation data we find γ=0.64☐.09, which is consistent with the prediction of General Relativity (γ≈0.55), though with a slight preference for higher γ and hence models with weaker gravitational interactions.Ībstract = "We measure Redshift-Space Distortions (RSD) in the two-point correlation function of a sample of 63,163 spectroscopically identified galaxies with z<0.2, an epoch where there are currently only limited measurements, from the Sloan Digital Sky Survey (SDSS) Data Release 7 Main Galaxy Sample. This latter measurement can be freely combined with recent Cosmic Microwave Background results to constrain the growth index of fluctuations, γ. We also measure fσ 8 including the AP effect. If we assume no Alcock-Paczynski (AP) effect (valid at z=0.15 for any smooth model of the expansion history), we measure the amplitude of the velocity field, fσ 8, at z=0.15 to be 0.49 +0.15 −0.14. Using errors derived from these mocks, we fit a model to the monopole and quadrupole moments of the MGS correlation function. Haloes are then selected using a friends-of-friends algorithm, and populated with galaxies using a Halo-Occupation Distribution fitted to the data. ![]() In order to validate the fitting methods used in both papers, and derive errors, we create and analyse 1000 mock catalogues using a new algorithm called PICOLA to generate accurate dark matter fields. ![]() Our sample, which we denote MGS, covers 6,813 deg 2 with an effective redshift z eff=0.15 and is described in our companion paper (Paper I), which concentrates on BAO measurements. We measure Redshift-Space Distortions (RSD) in the two-point correlation function of a sample of 63,163 spectroscopically identified galaxies with z<0.2, an epoch where there are currently only limited measurements, from the Sloan Digital Sky Survey (SDSS) Data Release 7 Main Galaxy Sample. ![]()
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