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Galaxy groups in the 2dFGRS: the group-finding algorithm and the 2PIGG catalogue

Eke, V.R.; Baugh, C.M.; Cole, S.; Frenk, C.S.; Norberg, P.; Peacock, J.A.; Baldry, I.K.; Bland-Hawthorn, J.; Bridges, T.; Cannon, R.; Colless, M.; Collins, C.; Couch, W.; Dalton, G.; de Propris, R.; Driver, S.P.; Efstathiou, G.; Ellis, R.S.; Glazebrook, K.; Jackson, C.; Lahav, O.; Lewis, I.; Lumsden, S.; Maddox, S.; Madgwick, D.; Peterson, B.A.; Sutherland, W.

Galaxy groups in the 2dFGRS: the group-finding algorithm and the 2PIGG catalogue Thumbnail


J.A. Peacock

I.K. Baldry

J. Bland-Hawthorn

T. Bridges

R. Cannon

M. Colless

C. Collins

W. Couch

G. Dalton

R. de Propris

S.P. Driver

G. Efstathiou

R.S. Ellis

K. Glazebrook

C. Jackson

O. Lahav

I. Lewis

S. Lumsden

S. Maddox

D. Madgwick

B.A. Peterson

W. Sutherland


The construction of a catalogue of galaxy groups from the Two-degree Field Galaxy Redshift Survey (2dFGRS) is described. Groups are identified by means of a friends-of-friends percolation algorithm which has been thoroughly tested on mock versions of the 2dFGRS generated from cosmological N-body simulations. The tests suggest that the algorithm groups all galaxies that it should be grouping, with an additional 40 per cent of interlopers. About 55 per cent of the 190 000 galaxies considered are placed into groups containing at least two members of which 29 000 are found. Of these, 7000 contain at least four galaxies, and these groups have a median redshift of 0.11 and a median velocity dispersion of 260 km s1. This 2dFGRS Percolation-Inferred Galaxy Group (2PIGG) catalogue represents the largest available homogeneous sample of galaxy groups. It is publicly available on the World Wide Web.


Eke, V., Baugh, C., Cole, S., Frenk, C., Norberg, P., Peacock, J., …Sutherland, W. (2004). Galaxy groups in the 2dFGRS: the group-finding algorithm and the 2PIGG catalogue. Monthly Notices of the Royal Astronomical Society, 348(3), 866-878.

Journal Article Type Article
Publication Date 2004-03
Deposit Date Feb 22, 2008
Publicly Available Date Aug 11, 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 348
Issue 3
Pages 866-878
Keywords Catalogues, Galaxies, Clusters.


Published Journal Article (1.6 Mb)

Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2004 The Authors Published on behalf of Royal Astronomical Society. All rights reserved.

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