J/ApJ/751/50 Catalog of galaxy groups from DEEP2 Redshift Survey (Gerke+ 2012)
The DEEP2 Galaxy Redshift Survey: the Voronoi-Delaunay method catalog of
galaxy groups.
Gerke B.F., Newman J.A., Davis M., Coil A.L., Cooper M.C., Dutton A.A.,
Faber S.M., Guhathakurta P., Konidaris N., Koo D.C., Lin L., Noeske K.,
Phillips A.C., Rosario D.J., Weiner B.J., Willmer C.N.A., Yan R.
<Astrophys. J., 751, 50 (2012)>
=2012ApJ...751...50G 2012ApJ...751...50G
ADC_Keywords: Clusters, galaxy ; Velocity dispersion ; Redshifts
Keywords: galaxies: clusters: general, galaxies: high-redshift
Abstract:
We present a public catalog of galaxy groups constructed from the
spectroscopic sample of galaxies in the fourth data release from the
Deep Extragalactic Evolutionary Probe 2 (DEEP2) Galaxy Redshift
Survey, including the Extended Groth Strip (EGS). The catalog contains
1165 groups with two or more members in the EGS over the redshift
range 0<z<1.5 and 1295 groups at z>0.6 in the rest of DEEP2. 25% of
EGS galaxies and 14% of high-z DEEP2 galaxies are assigned to galaxy
groups. The groups were detected using the Voronoi-Delaunay method
(VDM) after it has been optimized on mock DEEP2 catalogs following
similar methods to those employed in Gerke et al (2005, J/ApJ/625/6).
In the optimization effort, we have taken particular care to ensure
that the mock catalogs resemble the data as closely as possible, and
we have fine-tuned our methods separately on mocks constructed for the
EGS and the rest of DEEP2. We have also probed the effect of the
assumed cosmology on our inferred group-finding efficiency by
performing our optimization on three different mock catalogs with
different background cosmologies, finding large differences in the
group-finding success we can achieve for these different mocks. Using
the mock catalog whose background cosmology is most consistent with
current data, we estimate that the DEEP2 group catalog is 72% complete
and 61% pure (74% and 67% for the EGS) and that the group finder
correctly classifies 70% of galaxies that truly belong to groups, with
an additional 46% of interloper galaxies contaminating the catalog
(66% and 43% for the EGS). We also confirm that the VDM catalog
reconstructs the abundance of galaxy groups with velocity dispersions
above ∼300 km/s to an accuracy better than the sample variance, and
this successful reconstruction is not strongly dependent on cosmology.
Description:
DEEP2 spectroscopic observations were carried out using the 1200-line
diffraction grating on DEIMOS, giving a spectral resolution of R∼6000.
This yields a velocity accuracy of ∼30km/s. Targets for DEIMOS
spectroscopy were selected down to a limiting magnitude of R=24.1 from
three-band (BRI) photometric observations taken with the CFH12k imager
on the Canada-France-Hawaii Telescope (Coil et al. 2004, Cat. II/301).
Groups are detected using the Voronoi-Delaunay method (VDM) group
finder (Marinoni et al. 2002ApJ...580..122M 2002ApJ...580..122M), as optimized on new,
highly realistic mock galaxy catalogs, using similar techniques to the
ones we developed in G05 (Gerke et al, 2005, Cat. J/ApJ/625/6) for
early DEEP2 data, using a previous generation of DEEP2 mocks. The
catalogs developed here replace those presented in G05.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 44 2460 The DEEP2 Voronoi-Delaunay method (VDM) group catalog
table4.dat 13 6170 Galaxies in the DEEP2 VDM group catalog and the
ID numbers of their host groups
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See also:
II/301 : The DEEP2-DR1 Photometric Catalog (Coil+ 2004)
III/268 : DEEP2 Redshift Survey, Data Release 4 (Matthews+ 2013)
VII/86 : Groups of Galaxies. I. Nearby Groups (Huchra+ 1982)
J/A+A/520/A42 : Galaxy groups in the VIMOS-VLT Deep Survey (Cucciati+, 2010)
J/ApJ/654/115 : DEEP2 Galaxy Redshift Survey: SDSS QSOs (Coil+, 2007)
J/MNRAS/377/806 : Tully-Fisher relation of DEEP2 galaxies (Chiu+, 2007)
J/ApJ/625/6 : Galaxy groups in the DEEP2 GRS (Gerke+, 2005)
J/ApJS/157/175 : DEEP Groth Strip Survey. VIII. (Koo+, 2005)
J/MNRAS/348/866 : 2dFGRS Percolation-Inferred Galaxy Group (2PIGG) (Eke+, 2004)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID [1/2500] Unique identification group number
(<[GND2012] NNNN> in Simbad)
6- 7 I2 h RAh Hour of Right Ascension (J2000) (1)
9- 10 I2 min RAm Minute of Right Ascension (J2000) (1)
12- 16 F5.2 s RAs Second of Right Ascension (J2000) (1)
18 A1 --- DE- Sign of the Declination (J2000) (1)
19- 20 I2 deg DEd Degree of Declination (J2000) (1)
22- 23 I2 arcmin DEm Arcminute of Declination (J2000) (1)
25- 28 F4.1 arcsec DEs Arcsecond of Declination (J2000) (1)
30- 33 F4.2 --- z [0.04/1.5] Redshift of the group (1)
35- 36 I2 --- Ng [2/21] Number of galaxies within the group
38- 40 I3 km/s sigV [0/960] Velocity dispersion σV
42- 44 A3 --- HP [Yes/No ] High-Purity? (2)
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Note (1): Median value of all galaxies in the group.
Note (2): Groups detected with both the standard and the high-purity
parameters are indicated as High-Purity.
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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- 8 I8 --- ObjNo Unique DEEP2 catalog galaxy identification
(<DEEP2-GRS NNNNNNNN> in Simbad)
10- 13 I4 --- ID [1/2500] Unique identification group number
as in Table 3
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 16-Dec-2013