Testing gravity using largescale redshiftspace distortions
Abstract
We use luminous red galaxies from the Sloan Digital Sky Survey (SDSS) II to test the cosmological structure growth in two alternatives to the standard Λ cold dark matter (ΛCDM)+general relativity (GR) cosmological model. We compare observed threedimensional clustering in SDSS Data Release 7 (DR7) with theoretical predictions for the standard vanilla ΛCDM+GR model, unified dark matter (UDM) cosmologies and the normal branch DvaliGabadadzePorrati (nDGP). In computing the expected correlations in UDM cosmologies, we derive a parametrized formula for the growth factor in these models. For our analysis we apply the methodology tested in Raccanelli et al. and use the measurements of Samushia et al. that account for survey geometry, nonlinear and wideangle effects and the distribution of pair orientation. We show that the estimate of the growth rate is potentially degenerate with wideangle effects, meaning that extremely accurate measurements of the growth rate on large scales will need to take such effects into account. We use measurements of the zeroth and secondorder moments of the correlation function from SDSS DR7 data and the Large Suite of Dark Matter Simulations (LasDamas), and perform a likelihood analysis to constrain the parameters of the models. Using information on the clustering up to r_{max} = 120 h^{1} Mpc, and after marginalizing over the bias, we find, for UDM models, a speed of sound c_{∞} ≤ 6.1e4, and, for the nDGP model, a crossover scale r_{c} ≥ 340 Mpc, at 95 per cent confidence level.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 November 2013
 DOI:
 10.1093/mnras/stt1517
 arXiv:
 arXiv:1207.0500
 Bibcode:
 2013MNRAS.436...89R
 Keywords:

 methods: analytical;
 cosmological parameters;
 cosmology: observations;
 largescale structure of Universe;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 12 pages, 20 figures