J/ApJS/167/1 Galaxy groups and clusters from SDSS (Berlind+, 2006)
Percolation galaxy groups and clusters in the SDSS redshift survey:
Identification, catalogs, and the multiplicity function.
Berlind A.A., Frieman J., Weinberg D.H., Blanton M.R., Warren M.S.,
Abazajian K., Scranton R., Hogg D.W., Scoccimarro R., Bahcall N.A.,
Brinkmann J., Gott J.R.III, Kleinman S.J., Krzesinski J., Lee B.C.,
Miller C.J., Nitta A., Schneider D.P., Tucker D.L., Zehavi I.,
(the SDSS Collaboration)
<Astrophys. J. Suppl. Ser., 167, 1-25 (2006)>
=2006ApJS..167....1B 2006ApJS..167....1B
ADC_Keywords: Clusters, galaxy ; Redshifts ; Velocity dispersion
Keywords: galaxies: clusters: general - large-scale structure of universe
Abstract:
We identify galaxy groups and clusters in volume-limited samples of
the Sloan Digital Sky Survey (SDSS) redshift survey, using a
redshift-space friends-of-friends algorithm. We optimize the
friends-of-friends linking lengths to recover galaxy systems that
occupy the same dark matter halos, using a set of mock catalogs
created by populating halos of N-body simulations with galaxies.
Extensive tests with these mock catalogs show that no combination
of perpendicular and line-of-sight linking lengths is able to yield
groups and clusters that simultaneously recover the true halo
multiplicity function, projected size distribution, and velocity
dispersion. We adopt a linking length combination that yields, for
galaxy groups with 10 or more members: a group multiplicity function
that is unbiased with respect to the true halo multiplicity function;
an unbiased median relation between the multiplicities of groups and
their associated halos; a spurious group fraction of less than ∼1%; a
halo completeness of more than 97%; the correct projected size
distribution as a function of multiplicity; and a velocity dispersion
distribution that is ∼20% too low at all multiplicities. These results
hold over a range of mock catalogs that use different input recipes of
populating halos with galaxies. We apply our group-finding algorithm
to the SDSS data and obtain three group and cluster catalogs for three
volume-limited samples that cover 3495.1deg2 on the sky, go out to
redshifts of 0.1, 0.068, and 0.045, and contain 57138, 37820, and
18895 galaxies, respectively. We correct for incompleteness caused by
fiber collisions and survey edges and obtain measurements of the group
multiplicity function, with errors calculated from realistic mock
catalogs. These multiplicity function measurements provide a key
constraint on the relation between galaxy populations and dark matter
halos.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 81 8148 Group and Cluster Catalogs for Samples
Mr20, Mr19, and Mr18
table4.dat 65 44554 Member Galaxies of Groups and Clusters for
Samples Mr20, Mr19, and Mr18
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See also:
J/A+A/312/745 : SSRS groups of galaxies redshift neighbourhood (Ramella+, 1996)
J/AN/321/101 : Compact groups of galaxies in LCRS (Allam+, 2000)
J/A+A/381/420 : Group of Galaxies in the SSRS2 catalog (Adami+, 2002)
J/AJ/123/2976 : The UZC-SSRS2 group catalog (Ramella+, 2002)
J/ApJ/625/6 : Galaxy groups in the DEEP2 Galaxy Redshift Survey (Gerke+ 2005)
J/A+A/479/927 : Group of galaxies in SDSS 5 (Tago+, 2008)
J/AN/327/365 : Clusters and groups of galaxies in 2dF (Tago+, 2006)
J/A+A/474/783 : Main galaxy groups from SDSS-DR5 (Deng+, 2007)
II/259 : The SDSS Photometric Catalog, Release 3 (Abazajian+ 2005)
http://sdss.org : SDSS Home Page
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Samp The volume-limited sample (G1)
6- 10 I5 --- Group Group identification number (1)
12- 21 F10.6 deg RAdeg Right Ascension (J2000) of group centroid
23- 32 F10.6 deg DEdeg Declination (J2000) of group centroid
34- 41 F8.5 --- z Mean redshift of the group
43- 45 I3 --- Rich Group richness
47- 53 F7.3 mag rMAG Total group r band absolute magnitude
55- 60 F6.3 mag g-r Total group (g-r) color index
62- 67 F6.1 km/s sigma Group velocity dispersion
69- 74 F6.3 Mpc RPerp Group projected rms radius (in h-1Mpc)
76- 81 F6.1 Mpc Redge Perpendicular distance of group center from
survey edge (in h-1Mpc)
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Note (1): Group identified as [BFW2006] MrNN NNNNN in Simbad
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Samp The R band sample (G1)
6- 10 I5 --- Group Group identification number (1)
12- 21 F10.6 deg RAdeg Galaxy Right Ascension in decimal
degrees (J2000)
23- 32 F10.6 deg DEdeg Galaxy Declination in decimal degrees (J2000)
34- 41 F8.5 --- z Galaxy redshift (2)
43- 49 F7.3 mag rMAG Galaxy r band absolute magnitude
51- 56 F6.3 mag g-r Galaxy (g-r) color index
58 I1 --- f_z [0/1] Fiber collision flag (3)
60- 65 F6.1 Mpc Redge Perpendicular distance of galaxy from the
survey edge (in h-1 Mpc)
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Note (1): Galaxies identified as [BFW2006] MrNN NNNNN DDD.dddddd-DD.dddddd
in Simbad.
Note (2): Galaxies without measured redshifts due to fiber collisions are
assigned the absolute magnitude of their nearest neighbor, as
described in Section 2.
Note (3): The value 1 indicates a galaxy with a redshift assigned from its
nearest neighbor; 0 indicates a galaxy has its own measured redshift
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Global notes:
Note (G1): The sample includes galaxies down to absolute r-band magnitudes:
Mr20 = -19.9;
Mr19 = -19;
Mr18 = -18
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History:
* 29-May-2008 : From electronic version of the journal
* 25-Mar-2009 : Corrections of declination sign in Tables 3 and 4.
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 29-May-2008