Galaxy And Mass Assembly (GAMA): improved cosmic growth measurements using multiple tracers of large-scale structure

Chris Blake*, I. K. Baldry, J. Bland-Hawthorn, L. Christodoulou, M. Colless, C. Conselice, S. P. Driver, A. M. Hopkins, J. Liske, J. Loveday, P. Norberg, J. A. Peacock, G. B. Poole, A. S. G. Robotham

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

164 Citations (Scopus)

Abstract

We present the first application of a 'multiple-tracer' redshift-space distortion (RSD) analysis to an observational galaxy sample, using data from the Galaxy and Mass Assembly (GAMA) survey. Our data set is an r <19.8 magnitude-limited sample of 178 579 galaxies covering the redshift interval z <0.5 and area 180 deg(2). We obtain improvements of 10-20 per cent in measurements of the gravitational growth rate compared to a single-tracer analysis, deriving from the correlated sample variance imprinted in the distributions of the overlapping galaxy populations. We present new expressions for the covariances between the auto-power and cross-power spectra of galaxy samples that are valid for a general survey selection function and weighting scheme. We find no evidence for a systematic dependence of the measured growth rate on the galaxy tracer used, justifying the RSD modelling assumptions, and validate our results using mock catalogues from N-body simulations. For multiple tracers selected by galaxy colour, we measure normalized growth rates in two independent redshift bins f Sigma(8)(z = 0.18) = 0.36 +/- 0.09 and f Sigma(8)(z = 0.38) = 0.44 +/- 0.06, in agreement with standard GR gravity and other galaxy surveys at similar redshifts.

Original languageEnglish
Pages (from-to)3089-3105
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Volume436
Issue number4
DOIs
Publication statusPublished - Dec 2013

Keywords

  • surveys
  • cosmological parameters
  • large-scale structure of Universe
  • DIGITAL SKY SURVEY
  • DARK ENERGY SURVEY
  • OSCILLATION SPECTROSCOPIC SURVEY
  • REDSHIFT-SPACE DISTORTIONS
  • DATA RELEASE
  • SDSS-III
  • LUMINOSITY
  • VARIANCE
  • STOCHASTICITY
  • SPECTRA

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