Testing gravity using large-scale redshift-space distortions

Alvise Raccanelli, Daniele Bertacca, Davide Pietrobon, Fabian Schmidt, Lado Samushia, Nicola Bartolo, Olivier Dore, Sabino Matarrese, Will J. Percival

Research output: Contribution to journalArticlepeer-review


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 three-dimensional 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 Dvali–Gabadadze–Porrati (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, non-linear and wide-angle effects and the distribution of pair orientation. We show that the estimate of the growth rate is potentially degenerate with wide-angle 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 second-order 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 rmax = 120 h−1 Mpc, and after marginalizing over the bias, we find, for UDM models, a speed of sound c ≤ 6.1e-4, and, for the nDGP model, a cross-over scale rc ≥ 340 Mpc, at 95 per cent confidence level.
Original languageEnglish
Pages (from-to)89-100
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - Nov 2013


  • methods: analytical
  • cosmological parameters
  • cosmology: observations
  • large-scale structure of Universe


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