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.

doi:10.1093/mnras/stt1791

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.

Authors

C. Blake

I.K. Baldry

J. Bland-Hawthorn

L. Christodoulou

M. Colless

C. Conselice

S.P. Driver

A.M. Hopkins

J. Liske

J. Loveday

Professor Peder Norberg peder.norberg@durham.ac.uk
Professor

J.A. Peacock

G.B. Poole

A.S.G. Robotham

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.

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This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2013 The Authors Published by Oxford University Press on behalf of Royal Astronomical Society. All rights reserved.