J/MNRAS/348/866 2dFGRS Percolation-Inferred Galaxy Group (2PIGG) (Eke+, 2004)
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., Taylor K.
<Mon. Not. R. Astron. Soc., 348, 866-878 (2004)>
=2004MNRAS.348..866E 2004MNRAS.348..866E
ADC_Keywords: Clusters, galaxy ; Redshifts
Keywords: catalogues - galaxies: clusters: general
Abstract:
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
∼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.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
2dfngpga.dat 69 78746 Galaxies used for group-finding in the NGP
2dfsgpga.dat 69 112694 Galaxies used for group-finding in the SGP
2dfngpgr.dat 77 11920 Group properties in the NGP
2dfsgpgr.dat 77 16957 Group properties in the SGP
mocngpga.dat 69 73195 Mock galaxies in the NGP
mocsgpga.dat 69 114189 Mock galaxies in the SGP
mocngpgr.dat 77 9861 Mock group properties in the NGP
mocsgpgr.dat 77 15340 Mock group properties in the SGP
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See also:
VII/250 : The 2dF Galaxy Redshift Survey (2dFGRS) (2dFGRS Team, 1998-2003)
Byte-by-byte Description of file: 2df*ga.dat moc*ga.dat
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Bytes Format Units Label Explanations
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3- 10 F8.5 rad RArad Right ascension in radians (1950 coordinates)
13- 20 F8.5 rad DErad Declination in radians (1950 coordinates)
24- 29 F6.4 --- z Redshift
32- 37 F6.3 mag bJmag bJ magnitude
40- 45 F6.3 mag bJmagl limiting b_J magnitude of the survey at the
position of this galaxy
48- 55 F8.6 --- n Mean number density of galaxies in the survey
at the position of this galaxy
59- 62 F4.2 --- Weight [1/4.4] Weight associated with this galaxy
65- 69 I5 --- Ngroup [0/16957] Group number to which this galaxy
has been assigned (0 is ungrouped) (1)
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Note (1): k refers to the kth entry in the corresponding group list,
i.e. "recno" of the Vizir groups files.
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Byte-by-byte Description of file: 2df*gr.dat moc*gr.dat
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Bytes Format Units Label Explanations
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1- 7 I7 --- Nmemb [1/500] Unweighted number of members
10- 21 E12.7 rad RArad Right ascension of group centre in
radians (1950 coordinates)
23- 35 E13.7 rad DErad Declination of group centre in radians
(1950 coordinates)
38- 49 E12.7 --- z Group redshift
52- 63 E12.7 Mpc Sep rms projected galaxy separation in Mpc/h
66- 77 E12.7 km/s sigma Group velocity dispersion
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History:
Copied at http://www.mso.anu.edu.au/2dFGRS/Public/2PIGG/
(End) Patricia Vannier [CDS] 23-Apr-2012