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arXiv · astro-ph/0402567

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

V. R. Eke·C. M. Baugh·S. Cole·C. S. Frenk·P. Norberg·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·K. Taylor
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Abstract

The construction of a catalogue of galaxy groups from the 2-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% of interlopers. About 55% of the ~190000 galaxies considered are placed into groups containing at least two members of which ~29000 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 260km/s. This 2dFGRS Percolation-Inferred Galaxy Group (2PIGG) catalogue represents the largest available homogeneous sample of galaxy groups. It is publicly available on the WWW.

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V. R. Eke, C. M. Baugh, S. Cole, C. S. Frenk, P. Norberg, 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, K. Taylor. 2004-02-26. Galaxy groups in the 2dFGRS: the group-finding algorithm and the 2PIGG catalogue. https://doi.org/10.1111/j.1365-2966.2004.07408.x

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