J/A+A/520/A42 Galaxy groups in the VIMOS-VLT Deep Survey (Cucciati+, 2010)
The VIMOS-VLT Deep Survey: the group catalogue.
Cucciati O., Marinoni C., Iovino A., Bardelli S., Adami C., Mazure A.,
Scodeggio M., Maccagni D., Temporin S., Zucca E., De Lucia G., Blaizot J.,
Garilli B., Meneux B., Zamorani G., Le Fevre O., Cappi A., Guzzo L.,
Bottini D., Le Brun V., Tresse L., Vettolani G., Zanichelli A., Arnouts S.,
Bolzonella M., Charlot S., Ciliegi P., Contini T., Foucaud S.,
Franzetti P., Gavignaud I., Ilbert O., Lamareille F., McCracken H. J.,
Marano B., Merighi R., Paltani S., Pella R., Pollo A., Pozzetti L.,
Vergani D., Perez-Montero E.
<Astron. Astrophys. 520, A42 (2010)>
=2010A&A...520A..42C 2010A&A...520A..42C
ADC_Keywords: Surveys ; Clusters, galaxy ; Redshifts ; Velocity dispersion
Keywords: galaxies: clusters: general - large-scale structure of Universe -
galaxies: high-redshift - galaxies: evolution - galaxies: statistics
Abstract:
We present a homogeneous and complete catalogue of optical galaxy
groups identified in the VIMOS-VLT Deep Survey (VVDS). We use mock
catalogues extracted from the Millennium Simulation to study the
potential systematics that might affect the overall distribution of
the identified systems, and also to asses how well galaxy redshifts
trace the line-of-sight velocity dispersion of the underlying mass
overdensity. We train on these mock catalogues the adopted
group-finding technique (the Voronoi-Delaunay Method, VDM), to recover
in a robust and unbiased way the redshift and velocity dispersion
distributions of groups and maximize the level of completeness (C) and
purity (P) of the group catalogue. We identify 318(/144) VVDS groups
with at least 2(/3) members within 0.2≤z≤1.0, globally with C=60%
and P=50%. We use the group sample to study the redshift evolution of
the fraction fb of blue galaxies (U-B≤1) within 0.2≤z≤1 in both
groups and in the whole ensemble of galaxies irrespectively of their
environment.
Description:
We have compiled a homogeneous catalogue of optical galaxy groups
identified in the VVDS-02h field (0.7x0.7deg2) by means of the VDM
algorithm, in the range 0.2≤z≤1.0. We give the coordinates (RA, DE
and z) and a few properties (velocity dispersion, number of galaxy
members) of the so-found groups. We also list the galaxies that belong
to these groups (ID, RA, DE, z, quality of redshift measurement).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 68 318 Location and properties of groups within 0.2≤z≤1
table5.dat 73 904 Id and location of galaxies in the groups
listed in Table 4
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See also:
III/250 : The VIMOS VLT deep survey (VVDS-DEEP) (Le Fevre+ 2005)
http://cencosw.oamp.fr : VVDS database
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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8- 10 I3 --- GrID Group ID
14 A1 --- n_GrID [*] Detection with only flag 3-4 galaxies (1)
18- 25 F8.5 deg RAdeg Right ascension in decimal degrees (J2000) (2)
30- 37 F8.5 deg DEdeg Declination in decimal degrees (J2000) (3)
44- 49 F6.4 --- z Redshift (4)
53- 54 I2 --- Ngal Number of galaxies
58- 61 I4 km/s sigma Velocity dispersion (5)
68 A1 --- HPDet [H] High purity detection (6)
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Note (1): "*" indicates that the group has been detected also if using only
the galaxies with the highest redshift measurement quality (flag 3 and
4, i.e. ≥95% confidence)
Note (2): Median value of the the Right ascension of the galaxies in the group
Note (3): Median value of the the Declination of the galaxies in the group
Note (4): Median value of the the redshift of the galaxies in the group
Note (5): sigma=0 means that the mean redshift measurement error in VVDS is
higher than the estimated sigma (see the paper for more details)
Note (6): "H" means that the group has been detected also when running the
algorithm with high purity parameter set (see the paper for more details)
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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2- 10 I09 --- GalID Galaxy ID (CENCOS database) (1)
18- 25 F8.5 deg RAdeg Right ascension in decimal degrees (J2000)
31- 38 F8.5 deg DEdeg Declination in decimal degrees (J2000)
43- 48 F6.4 --- z Redshift
55- 56 I2 --- q_Zz Flag for quality redshift measurement (2)
64- 66 I3 --- GrID ID of the group to which the galaxy belongs(3)
72- 73 I2 --- Ngal Number of galaxies in the group
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Note (1): The galaxy ID refers to the public VVDS release at
http://cencosw.oamp.fr; see also Cat. III/250
Note (2): The flag indicates the likelihood with which the redshift of the
galaxy has been estimated as follows:
1 = around 50%
2 = around 80%
3 = around 97%
4 = around 99%
9 = around 50%, only one emission line
2x = when one of the above-mentioned flags is preceded by the
digit "2", it means that it is a secondary object in the slit.
For more details see Le Fevre et al. (2005A&A...439..845L 2005A&A...439..845L,
Cat. III/250)
Note (3): It corresponds to the group ID in the first column of table 4.
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Acknowledgements:
Olga Cucciati, olga.cucciati(at)oamp.fr
References:
Le Fevre et al., 2005A&A...439..845L 2005A&A...439..845L, Cat. III/250
(End) Olga Cucciati [LAM, France], Patricia Vannier [CDS] 06-Aug-2010