J/A+A/514/A102 SDSS DR7 groups of galaxies (Tago+, 2010)
Groups of galaxies in the SDSS Data Release 7. Flux- and volume-limited samples.
Tago E., Saar E., Tempel E., Einasto J., Einasto M., Nurmi P., Heinamaki P.
<Astron. Astrophys. 514, A102 (2010)>
=2010A&A...514A.102T 2010A&A...514A.102T
ADC_Keywords: Galaxy catalogs ; Clusters, galaxy ; Galaxies, photometry
Keywords: cosmology: observations - large-scale structure of the Universe -
galaxies: clusters: general - catalogues
Abstract:
We extract groups of galaxies as flux-limited and volume-limited
samples from the SDSS Data Release 7 to study the supercluster-void
network and environmental properties of groups therein. Volume-limited
catalogues are particularly useful for comparison of numerical
simulations of dark matter halos and the large-scale structure with
observations. Extraction of a volume-limited sample of galaxies and
groups requires special care to avoid excluding too much observational
data. We use a modified friends-of-friends (FoF) method with a
slightly variable linking length to obtain a preliminary flux-limited
sample. We use the flux-limited groups as the basic sample to include
as many galaxies as possible in the volume-limited samples. To
determine the scaling of the linking length we calibrated group sizes
and mean galaxy number densities within groups by magnitude dilution
of a nearby group sub-sample to follow the properties of groups with
higher luminosity limits. Our final flux-limited sample contains 78800
groups, and volume-limited subsamples with absolute magnitude limits
Mr=-18, -19, -20, and -21 contain 5463, 12590, 18973, and 9139
groups, respectively, in the DR7 main galaxy main area survey. The
spatial number densities of our groups within the subsamples, as well
as the mean sizes and rms velocities of our groups practically do not
change from sub-sample to sub-sample. This means that the catalogues
are homogeneous and well suited for comparison with simulations.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2a.dat 104 78800 DR7 flux-limited groups
table2b.dat 104 5463 DR7 flux-limited Mr < -18 groups
table2c.dat 104 12590 DR7 flux-limited Mr < -19 groups
table2d.dat 104 18973 DR7 flux-limited Mr < -20 groups
table2e.dat 104 9139 DR7 flux-limited Mr < -21 groups
table2f.dat 118 583362 DR7 flux-limited galaxies
table2g.dat 118 40665 DR7 volume-limited Mr < -18 galaxies
table2h.dat 118 94912 DR7 volume-limited Mr < -19 galaxies
table2i.dat 118 148195 DR7 volume-limited Mr < -20 galaxies
table2j.dat 118 103978 DR7 volume-limited Mr < -21 galaxies
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See also:
J/A+AS/123/119 : The supercluster-void network. I. (Einasto+ 1997)
J/A+A/336/35 : Shape and orientation of superclusters (Jaaniste+, 1998)
J/AJ/122/2222 : Superclusters of Abell and X-ray clusters (Einasto+, 2001)
J/AJ/123/51 : Distribution of Abell and APM clusters (Einasto+, 2002)
J/A+A/459/L1 : Supercluster sample from SDSS DR4 (Einasto+, 2006)
J/AN/327/365 : Clusters and groups of galaxies in 2dF (Tago+, 2006)
J/A+A/479/927 : Group of galaxies in SDSS 5 (Tago+, 2008)
J/A+A/462/811 : Superclusters of galaxies from 2dF (Einasto+, 2007)
Byte-by-byte Description of file: table2[abcde].dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Group Group identification number
8- 12 I5 --- Ngal Richness (number of member galaxies)
14- 25 F12.8 deg RAdeg Right Ascension (mean of member galaxies), J2000
27- 38 F12.8 deg DEdeg Declination (mean of member galaxies), J2000
40- 47 F8.4 Mpc Dist Comoving distance (mean of member galaxies) (G1)
49- 55 F7.4 Mpc Size Maximum projected linear size (G1)
57- 65 F9.6 Mpc dispD rms deviation of projected distance (G1)
67- 75 F9.4 km/s dispV rms radial velocity
77- 85 F9.6 Mpc Rvir Virial radius (projected harmonic mean) (G1)
87- 92 F6.3 --- w Luminosity weight
95-104 F10.6 10+10Lsun Lobs Observed total group luminosity (G1)
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Byte-by-byte Description of file: table2[fghij].dat
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Bytes Format Units Label Explanations
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2- 7 I6 --- Group Group ID number
10- 14 I5 --- Ngal Group richness
16- 27 F12.8 deg RAdeg Right Ascension (J2000.0)
29- 40 F12.8 deg DEdeg Declination (J2000.0)
42- 49 F8.4 Mpc Dist Co-moving distance corrected for CMB (G1)
51- 59 F9.5 mag uMAG Absolute u magnitude
61- 69 F9.5 mag gMAG Absolute g magnitude
71- 79 F9.5 mag rMAG Absolute r magnitude
81- 89 F9.5 mag iMAG Absolute i magnitude
91- 99 F9.5 mag zMAG Absolute z magnitude
101-106 F6.4 --- w Luminosity weight
110-118 F9.6 10+10Lsun Lr Luminosity in r band (1010/h2)(G1)
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Global notes:
Note (G1): cosmology with h=H0/100,
Ωm=0.27, ΩΛ=0.73.
* Distances are in Mpc/h
* Luminosities are in 10+10L☉/h2
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Acknowledgements:
Erik Tago, erik(at)aai.ee
(End) Erik Tago [Tartu Obs., Estonia], Patricia Vannier [CDS] 10-Mar-2010