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Keywords:

  • surveys;
  • Cosmology: observations;
  • dark energy – large-scale structure of Universe

ABSTRACT

We explore the benefits of using a passively evolving population of galaxies to measure the evolution of the rate of structure growth between z = 0.25 and 0.65 by combining data from the Sloan Digital Sky Survey (SDSS) I/II and SDSS-III surveys. The large-scale linear bias of a population of dynamically passive galaxies, which we select from both surveys, is easily modelled. Knowing the bias evolution breaks degeneracies inherent to other methodologies, and decreases the uncertainty in measurements of the rate of structure growth and the normalization of the galaxy power spectrum by up to a factor of 2. If we translate our measurements into a constraint on σ8(z = 0) assuming a concordance cosmological model and general relativity (GR), we find that using a bias model improves our uncertainty by a factor of nearly 1.5. Our results are consistent with a flat Λ cold dark matter model and with GR.