The 6dF Galaxy Survey: Bulk Flows on 50−70h−1 Mpc scales

Scrimgeour, Morag I.; Davis, Tamara M.; Blake, Chris; Staveley-Smith, Lister; Magoulas, Christina; Springob, Christopher M.; Beutler, Florian; Colless, Matthew; Johnson, Andrew; Jones, D. Heath; Koda, Jun; Lucey, John R.; Ma, Yin-Zhe; Mould, Jeremy; Poole, Gregory B.

doi:10.1093/mnras/stv2146

The 6dF Galaxy Survey: Bulk Flows on 50−70h−1 Mpc scales

Scrimgeour, Morag I.; Davis, Tamara M.; Blake, Chris; Staveley-Smith, Lister; Magoulas, Christina; Springob, Christopher M.; Beutler, Florian; Colless, Matthew; Johnson, Andrew; Jones, D. Heath; Koda, Jun; Lucey, John R.; Ma, Yin-Zhe; Mould, Jeremy; Poole, Gregory B.

Authors

Morag I. Scrimgeour

Tamara M. Davis

Chris Blake

Lister Staveley-Smith

Christina Magoulas

Christopher M. Springob

Florian Beutler

Matthew Colless

Andrew Johnson

D. Heath Jones

Jun Koda

Dr John Lucey john.lucey@durham.ac.uk
Emeritus Professor

Yin-Zhe Ma

Jeremy Mould

Gregory B. Poole

Abstract

We measure the bulk flow of the local Universe using the 6dF Galaxy Survey peculiar velocity sample (6dFGSv), the largest and most homogeneous peculiar velocity sample to date. 6dFGSv is a Fundamental Plane sample of ∼104 peculiar velocities covering the whole Southern hemisphere for galactic latitude |b| > 10°, out to redshift z = 0.0537. We apply the ‘minimum variance’ bulk flow weighting method, which allows us to make a robust measurement of the bulk flow on scales of 50 and 70 h−1 Mpc. We investigate and correct for potential bias due to the lognormal velocity uncertainties, and verify our method by constructing Λ cold dark matter (ΛCDM) 6dFGSv mock catalogues incorporating the survey selection function. For a hemisphere of radius 50 h−1 Mpc we find a bulk flow amplitude of U = 248 ± 58 km s−1 in the direction (l, b) = (318° ± 20°, 40° ± 13°), and for 70 h−1 Mpc we find U = 243 ± 58 km s−1, in the same direction. Our measurement gives us a constraint on σ8 of 1.01+1.07−0.581.01−0.58+1.07. Our results are in agreement with other recent measurements of the direction of the bulk flow, and our measured amplitude is consistent with a ΛCDM prediction.

Citation

Scrimgeour, M. I., Davis, T. M., Blake, C., Staveley-Smith, L., Magoulas, C., Springob, C. M., …Poole, G. B. (2016). The 6dF Galaxy Survey: Bulk Flows on 50−70h−1 Mpc scales. Monthly Notices of the Royal Astronomical Society, 455(1), 386-401. https://doi.org/10.1093/mnras/stv2146

Journal Article Type	Article
Acceptance Date	Sep 15, 2015
Online Publication Date	Nov 2, 2015
Publication Date	Jan 1, 2016
Deposit Date	Dec 22, 2015
Publicly Available Date	Jan 25, 2016
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	455
Issue	1
Pages	386-401
DOI	https://doi.org/10.1093/mnras/stv2146
Keywords	Surveys, Galaxies: kinematics and dynamics, Galaxies: statistics, Cosmology: observations large-scale structure of Universe.
Related Public URLs	http://arxiv.org/abs/1511.06930

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Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.