J/MNRAS/443/2679 GEEC2 spectroscopic survey of Galaxy groups (Balogh+, 2014)
The GEEC2 spectroscopic survey of Galaxy groups at 0.8 < z < 1.
Balogh M.L., Mcgee S.L., Mok A., Wilman D.J., Finoguenov A., Bower R.G.,
Mulchaey J.S., Parker L.C., Tanaka M.
<Mon. Not. R. Astron. Soc., 443, 2679-2694 (2014)>
=2014MNRAS.443.2679B 2014MNRAS.443.2679B
ADC_Keywords: Clusters, galaxy ; Redshifts ; Equivalent widths ;
Velocity dispersion
Keywords: galaxies: evolution - galaxies: groups: general
Abstract:
We present the data release of the Gemini-South GMOS spectroscopy in
the fields of 11 galaxy groups at 0.8<z<1, within the COSMOS field.
This forms the basis of the Galaxy Environment Evolution Collaboration
2 (GEEC2) project to study galaxy evolution in haloes with
M∼1013M☉ across cosmic time. The final sample includes 162
spectroscopically confirmed members with R<24.75, and is >50%
complete for galaxies within the virial radius, and with stellar mass
Mstar>1010.3M☉. Including galaxies with photometric
redshifts, we have an effective sample size of ∼400 galaxies within
the virial radii of these groups. We present group velocity
dispersions, dynamical and stellar masses. Combining with the GCLASS
sample of more massive clusters at the same redshift, we find the
total stellar mass is strongly correlated with the dynamical mass,
with logM200=1.20(logMstar-12)+14.07. This stellar fraction of ∼1%
is lower than predicted by some halo occupation distribution models,
though the weak dependence on halo mass is in good agreement. Most
groups have an easily identifiable most massive galaxy (MMG) near the
centre of the galaxy distribution, and we present the spectroscopic
properties and surface brightness fits to these galaxies. The total
stellar mass distribution in the groups, excluding the MMG, compares
well with an NFW (Navarro Frenk & White) profile with concentration 4,
for galaxies beyond ∼0.2R200. This is more concentrated than the
number density distribution, demonstrating that there is some mass
segregation.
Description:
GEEC2 is a spectroscopic survey of galaxies in 11 groups, one of which
was serendipitously discovered in the background of the target, within
the COSMOS field. The spectroscopy was obtained with GMOS-South over
two semesters (2010A and 2011A). The original goal of the survey was
to observe ∼20 groups, with 3-4 spectroscopic masks each, to allow
an investigation of the intrinsic scatter within group populations.
However, repeated attempts to complete the programme have been
thwarted by bad weather, scheduling conflicts at Gemini, and variance
in ranking from semester to semester. Following the lack of any time
awarded in 2012B, attempts to extend the sample have been abandoned
for the moment.
Details of the target selection and spectroscopic observations have
been presented in Papers I-III.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 84 9245 Catalogue of spectroscopic redshifts
table2.dat 38 11 Properties of the 11 GEEC2 galaxy groups, published
in Paper 2 (Mok et al., 2013MNRAS.431.1090M 2013MNRAS.431.1090M)
table3.dat 104 11 Same groups as in Table 2, but with the coordinates
of the alternative centre
table4.dat 44 1250 Catalogue of group members
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See also:
J/ApJS/172/70 : zCOSMOS-bright catalog (Lilly+, 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 I7 --- Gal Galaxy identification number
9- 17 F9.5 deg RAdeg ?=- Right ascension (J2000)
19- 25 F7.5 deg DEdeg ?=- Declination (J2000)
27- 33 F7.4 --- z [-0.0006/4.2] Redshift
35- 38 F4.1 --- q_z [-2/29.5] Redshift quality, 4=secure (1)
40- 45 F6.2 [Msun] logM* ?=-99.99 Stellar mass (Chabrier IMF)
47- 50 F4.2 [Msun] E_logM* ?=0 Upper uncertainty on stellar mass
52- 55 F4.2 [Msun] e_logM* ?=0 Lower uncertainty on stellar mass
57- 62 F6.2 0.1nm EW[OII] ?=- [OII] equivalent width (rest frame)
64- 72 F9.2 0.1nm e_EW[OII] ?=- Uncertainty on EW[OII]
74- 76 A3 --- Class Classification: sf=star-forming, p=passive,
int=intermediate
78- 84 A7 --- Source Source (GEEC2 or zCOSMOS)
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Note (1): The 4 classes are 4=certain, 3=secure, 2=probable, 1=insecure.
Our sample incorporates the DR2 release of the 10K zCOSMOS spectroscopic
survey (Lilly et al. 2007, J/ApJS/172/70), see the definition of the
redshift quality therein. Note that our redhift is smaller than the
10K zCOSMOS survey by Δz=0.00062, and the zCOSMOS redshifts were
adjusted here by this amount.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Group [40/213] Group ID number
4 A1 --- m_Group [a] Multiplicity index on Group
6- 12 F7.3 deg RAdeg Mean right ascension (J2000)
14- 18 F5.3 deg DEdeg Mean declination (J2000)
20- 25 F6.4 --- z [0.8/0.98] Median redshift
27 I1 --- Nmask [2/4] Number of masks observed in each field
29- 30 I2 --- Nmem [5/34] Number of group members
32- 34 I3 km/s sigma Rest-frame velocity dispersion σ as
measured, without correction for any bias
36- 38 I3 km/s e_sigma rms uncertainty on sigma
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Group [40/213] Group ID number
4 A1 --- m_Group [a] Multiplicity index in Group
6- 12 F7.3 deg RA1deg Alternative center right ascension (J2000)
14- 18 F5.3 deg DE1deg Alternative center declination (J2000)
20- 22 I3 km/s sigmai Intrinsic velocity dispersion estimate (1)
24- 26 I3 km/s e_sigmai rms uncertainty on sigmai
28- 31 F4.2 Mpc Rrms Radius (rms offset from group mean position)
33- 36 F4.2 Mpc e_Rrms rms uncertainty on Rrms
38- 41 F4.1 10+13Msun Mrms Mass within Rrms radius
43- 45 F3.1 10+13Msun e_Mrms rms uncertainty on Mrms
47- 50 F4.1 10+11Msun M*rms Stellar mass within Rrms radius (r<Rrms)
52- 55 F4.1 10+11Msun E_M*rms Upper uncertainty on M*rms
57- 60 F4.1 10+11Msun e_M*rms Upper uncertainty on M*rms
62- 65 F4.2 Mpc R200 Radius R200 (200 critical Universe density)
67- 70 F4.2 Mpc e_R200 rms uncertainty on R200
72- 75 F4.1 10+13Msun M200 Mass within R200 radius
77- 80 F4.1 10+13Msun e_M200 rms uncertainty on M200
82- 85 F4.1 10+11Msun M*200 Stellar mass within R200 radius (r<R200)
87- 90 F4.1 10+11Msun E_M*200 Upper uncertainty on M*200
92- 95 F4.1 10+11Msun e_M*200 Lower uncertainty on M*200
97-100 F4.1 10+13Msun M200X ?=- Equivalent mass as estimated from the
X-ray luminosity (2)
102-104 F3.1 10+13Msun e_M200X ? rms uncertainty on M200X
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Note (1): where we have applied corrections for limited sampling, 2σ
clipping, and redshift uncertainties. This is combined with the Rrms size
(as published in Paper 2) to give an updated mass estimate Mrms.
Note (2): This is unavailable for the serendipitous group, 213a. We note that
groups 121 and 161 as we have defined them here may also be serendipitous,
in the sense that they may not be associated with the targeted X-ray emission.
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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- 3 I3 --- Group [40/213] Group ID number
4 A1 --- m_Group [a] Multiplicity index on Group
6- 12 I7 --- Gal Galaxy ID number
14- 19 F6.4 --- zsp [0.82/0.98]?=- Spectroscopic redshift
21- 24 F4.2 --- zph [0.4/2.3] Photometric redshift
26- 29 F4.2 --- E_zph Upper uncertainty on photo-z
31- 34 F4.2 --- e_zph Lower uncertainty on photo-z
36- 39 F4.2 --- Pmb [0/1] Photo-z probability of being a group member
41- 44 F4.2 Mpc Dist [0/2.5] Distance from group centre
(mass-weighted mean of passive population)
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History:
From electronic version of the journal
References:
Balogh et al., Paper I 2011MNRAS.412.2303B 2011MNRAS.412.2303B
Mok et al., Paper II 2013MNRAS.431.1090M 2013MNRAS.431.1090M
Mok et al., Paper III 2014MNRAS.438.3070M 2014MNRAS.438.3070M
(End) Patricia Vannier [CDS] 20-Apr-2015