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

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

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 deg2. 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 fσ8(z = 0.18) = 0.36 ± 0.09 and fσ8(z = 0.38) = 0.44 ± 0.06, in agreement with standard GR gravity and other galaxy surveys at similar redshifts.

Citation

Blake, C., Baldry, I., Bland-Hawthorn, J., Christodoulou, L., Colless, M., Conselice, C., …Robotham, A. (2013). Galaxy And Mass Assembly (GAMA): improved cosmic growth measurements using multiple tracers of large-scale structure. Monthly Notices of the Royal Astronomical Society, 436(4), 3089-3105. https://doi.org/10.1093/mnras/stt1791

• Journal Article Type: Article
• Publication Date: Dec 1, 2013
• Deposit Date: Jun 3, 2014
• Publicly Available Date: Jul 3, 2014
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 436
• Issue: 4
• Pages: 3089-3105
• DOI: https://doi.org/10.1093/mnras/stt1791
• Keywords: Surveys, Cosmological parameters, Large-scale structure of Universe.
• Public URL: https://durham-repository.worktribe.com/output/1429577