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 and Robotham, A S G (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). pp. 3089-3105. ISSN 0035-8711

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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

Item Type: Article
Additional Information: Advance Access publication 2013 October 22
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy > QB0349 Theoretical astronomy and celestial mechanics
Depositing User: Catrina Hey
Date Deposited: 12 Mar 2014 16:13
Last Modified: 02 Jul 2019 20:17

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