J/A+A/540/A106 SDSS-DR8 groups and clusters of galaxies (Tempel+, 2012)
Groups and clusters of galaxies in the SDSS DR8. Value-added catalogues.
Tempel E., Tago E., Liivamagi L.J.
<Astron. Astrophys. 540, A106 (2012)>
=2012A&A...540A.106T 2012A&A...540A.106T
ADC_Keywords: Clusters, galaxy ; Galaxy catalogs ; Galaxies, photometry
Keywords: catalogs - galaxies: clusters: general - galaxies: groups: general -
galaxies: statistics - large-scale structure of Universe -
cosmology: observations
Abstract:
We create a new catalogue of groups and clusters for the SDSS Data
Release 8 sample. We add environmental parameters to our catalogue,
together with other galaxy parameters (e.g., morphology), missing from
our previous catalogues.
We use a modified friends-of-friends (FoF) method with a variable
linking length in the transverse and radial directions to eliminate
selection effects and to find reliably as many groups as possible to
track the supercluster network. We use the groups of galaxies as a
basis to determine the luminosity density field.
We take into account various selection effects caused by a magnitude
limited sample. Our final sample contains 576493 galaxies and 77858
groups. The group catalogue is available at
http://www.aai.ee/~elmo/dr8groups/ and from the Strasbourg
Astronomical Data Center (CDS).
Description:
Galaxy and group/cluster catalogues based on SDSS DR8 data are
presented. The tables are also available at
http://www.aai.ee/~elmo/dr8groups
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
dr8gal.dat 430 576493 Galaxy parameters
dr8gr.dat 236 77858 Group/cluster parameters
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See also:
II/306 : The SDSS Photometric Catalog, Release 8 (Adelman-McCarthy+, 2011)
J/A+A/514/A102 : SDSS DR7 groups of galaxies (Tago+, 2010)
J/A+A/479/927 : Group of galaxies in SDSS 5 (Tago+, 2008)
Byte-by-byte Description of file: dr8gal.dat
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Bytes Format Units Label Explanations
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2- 7 I6 --- ID Unique identification number for galaxies
9- 14 I6 --- IDcl [1/388773] Group/cluster ID number (1)
18- 20 I3 --- Ngal [1/878] Richness of group the galaxy
belongs to
22- 28 F7.5 --- z Redshift, corrected to CMB rest frame
30- 37 F8.4 Mpc Dist Co-moving distance of a galaxy (G1)
39- 46 F8.4 Mpc Dist.c Co-moving distance of the group centre (G1)
48- 57 F10.5 deg RAdeg Right ascension of galaxy (J2000)
59- 68 F10.5 deg DEdeg Declination of galaxy (J2000)
70- 79 F10.5 deg GLON Galactic longitude of galaxy
81- 90 F10.5 deg GLAT Galactic latitude of galaxy
92-101 F10.5 deg eta SDSS survey coordinate eta
103-112 F10.5 deg lambda SDSS survey coordinate lambda
114-121 F8.5 mag umag Galactic extinction corrected
Petrosian u-magnitude
123-130 F8.5 mag gmag Galactic extinction corrected
Petrosian g-magnitude
132-139 F8.5 mag rmag Galactic extinction corrected
Petrosian r-magnitude
141-148 F8.5 mag imag Galactic extinction corrected
Petrosian i-magnitude
150-157 F8.5 mag zmag Galactic extinction corrected
Petrosian z-magnitude
159-167 F9.5 mag uMAG Absolute u-magnitude (G1)
169-177 F9.5 mag gMAG Absolute g-magnitude (G1)
179-187 F9.5 mag rMAG Absolute r-magnitude (G1)
189-197 F9.5 mag iMAG Absolute i-magnitude (G1)
199-207 F9.5 mag zMAG Absolute z-magnitude (G1)
209-217 F9.5 mag kcoru K-correction in u-filter
219-227 F9.5 mag kcorg K-correction in g-filter
229-237 F9.5 mag kcorr K-correction in r-filter
239-247 F9.5 mag kcori K-correction in i-filter
249-257 F9.5 mag kcorz K-correction in z-filter
259-268 F10.5 10+10Lsun Lr r-band observed luminosity (G1)
270-275 F6.3 --- W Weight factor for the galaxy
279-281 I3 --- Rank [1/878] Galaxy rank in its group
283-293 F11.5 --- Den1 ?=-999 Normalised environmental density at
1Mpc/h (G1)
295-305 F11.5 --- Den2 ?=-999 Normalised environmental density at
2Mpc/h (G1)
307-317 F11.5 --- Den4 ?=-999 Normalised environmental density at
4Mpc/h (G1)
319-329 F11.5 --- Den8 ?=-999 Normalised environmental density at
8Mpc/h (G1)
331-341 F11.5 --- Den16 ?=-999 Normalised environmental density at
16Mpc/h (G1)
343-350 F8.4 Mpc Edge Co-moving distance from the survey mask (G1)
352 I1 --- Mph [0/2] Morphology of galaxy, 1=S, 2=E (2)
354-360 F7.5 --- prE Probability of being an early type galaxy
362-381 A20 --- DR8objid Approximative SDSS DR8 photometric objID (3)
383-402 A20 --- DR8spec Approximative SDSS DR8 spectroscopic ID (3)
404-409 I6 --- IDDR7 ID number to link to our previous DR7 cat
411-417 F7.5 --- zobs Observed redshift (without CMB correction)
419-426 F8.4 Mpc Distcor Corrected co-moving distance of galaxy (G1)
(in Mpc/h)
430 I1 --- fc [0/5] Number of missing neighbours
(fibre collision) (G2)
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Note (1): Groups with IDcl>77858 have only 1 galaxy.
Note (2): Morphology code is:
0 = unclear;
1 = spiral;
2 = elliptical
Note (3): IDs do not match the SDSS-DR8 ones (the 8 rightmost bits of the
binary reporesentation were all set to zero, i.e. the correct SDSS-DR8
ID is a number between DR8objid and DR8objid+255).
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Byte-by-byte Description of file: dr8gr.dat
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Bytes Format Units Label Explanations
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3- 7 I5 --- IDcl [1/77858] Group/cluster ID number
11- 13 I3 --- Ngal [2/878] Group richness
15- 21 F7.5 --- zcl Redshift to the group centre
23- 30 F8.4 Mpc Dist.c Co-moving distance to the group centre (G1)
32- 41 F10.5 deg RAdeg Right ascension of group centre (J2000)
43- 52 F10.5 deg DEdeg Declination of group centre (J2000)
54- 63 F10.5 deg GLON Galactic longitude
65- 74 F10.5 deg GLAT Galactic latitude
76- 85 F10.5 deg eta SDSS survey coordinate eta
87- 96 F10.5 deg lambda SDSS survey coordinate lambda
98-105 F8.5 Mpc Size Max linear size of the group in the sky (G1)
107-114 F8.5 Mpc Rvir Virial radius (projected harmonic mean) (G1)
116-123 F8.5 Mpc sigma Extent of the group in the sky (G1)
125-134 F10.4 km/s sigmav rms radial velocity deviation
136-145 F10.5 10+10Lsun Lrobs r-band observed luminosity (G1)
147-156 F10.5 10+10Lsun Lrtot r-band estimated total luminosity (G1)
158-163 F6.3 Mpc Dlink Co-moving linking length (G1)
165-175 F11.5 --- Den1 ?=-999 Environmental density for group at
a=1Mpc/h (G1)
177-187 F11.5 --- Den2 ?=-999 Environmental density for group at
a=2Mpc/h (G1)
189-199 F11.5 --- Den4 ?=-999 Environmental density for group at
a=4Mpc/h (G1)
201-211 F11.5 --- Den8 ?=-999 Environmental density for group at
a=8Mpc/h (G1)
213-223 F11.5 --- Den16 ?=-999 Environmental density for group at
a=16Mpc/h (G1)
225-232 F8.4 Mpc Edge Minimum distance from survey mask (G1)
235-236 I2 --- fc [0/64] Number of potentially missing fibre
collision galaxies (G2)
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Global Notes:
Note (G1): Throughout this study, the cosmology is defined with
H0=100h km/s/Mpc, ΩM=0.27 and ΩΛ=0.73.
* Distances are in Mpc/h
* distance modulus are in mag+5log10(h)
* luminosities are in L☉/h2
Note (G2): if greater than zero, indicates that the galaxy has a missing
(with unknown redshift) neighbour due to a fibre collision.
Acknowledgements:
Elmo Tempel, elmo (at)aai.ee
History:
* 28-Feb-2012: Original version
* 12-Jun-2012: warning added for the DR8objid and DR8spec columns
of dr8gal (do not exactly match the DR8 objIDs)
(End) Elmo Tempel [Tartu Obs., Estonia], Patricia Vannier [CDS] 28-Feb-2012