J/ApJ/552/427 Galaxy groups a intermediate redshifts (Carlberg+, 2001)
Galaxy groups at intermediate redshift.
Carlberg R.G., Yee H.K.C., Morris S.L., Lin H., Hall P.B., Patton D.R.,
Sawicki M., Shepherd C.W.
<Astrophys. J., 552, 427-444 (2001)>
=2001ApJ...552..427C 2001ApJ...552..427C
ADC_Keywords: Redshifts ; Velocity dispersion ; Surveys
Keywords: galaxies: evolution - large-scale structure of universe
Abstract:
Galaxy groups likely to be virialized are identified within the CNOC2,
(Yee et al., 2000, Cat. J/ApJS/129/475) intermediate-redshift galaxy
survey. The resulting groups have a median velocity dispersion,
σ1≃200km/s. The virial mass-to-light ratios, using k-corrected
and evolution-compensated luminosities, have medians in the range of
150-250h M{suns}/L☉, depending on group definition details.
The number-velocity dispersion relation at σ1≳200km/s is in
agreement with the low-mass extrapolation of the cluster-normalized
Press-Schechter model. Lower velocity dispersion groups are deficient
relative to the Press-Schechter model. The two-point group-group
autocorrelation function has r0=6.8±0.3h-1Mpc, which is much
larger than the correlations of individual galaxies, but about as
expected from biased clustering. The mean number density of galaxies
around group centers falls nearly as a power law with r-2.5 and has
no well-defined core. The projected velocity dispersion of galaxies
around group centers is either flat or slowly rising outward. The
combination of a steeper than isothermal density profile and the
outward rising velocity dispersion implies that the mass-to-light
ratio of groups rises with radius if the velocity ellipsoid is
isotropic but could be nearly constant if the galaxy orbits are nearly
circular. Such strong tangential anisotropy is not supported by other
evidence. Although the implication of a rising M/L must be viewed with
caution, it could naturally arise through dynamical friction acting on
the galaxies in a background of "classical" collisionless dark matter.
Description:
A group is defined here as a collection of three or more galaxies,
above a fixed minimum luminosity, that meet a set of positional
requirements designed to minimize chance associations. Here we
specifically seek virialized groups, which are collapsed and hence
quite dense compared to groups that are only required to be bound.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 71 190 The rzmax=5h-1Mpc, rpmax=0.25h-1Mpc
groups
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See also:
VII/256 : Groups of Galaxies from CfA2 Redshift Survey (Mahtessian++, 2010)
VII/213 : Hickson's Compact groups of Galaxies (Hickson+ 1982-1994)
J/A+A/474/783 : Main galaxy groups from SDSS-DR5 (Deng+, 2007)
J/ApJ/625/6 : Galaxy groups in the DEEP2 Galaxy Redshift Survey (Gerke+,
2005)
J/AJ/123/2976 : The UZC-SSRS2 group catalog (Ramella+, 2002)
J/A+A/381/420 : Group of Galaxies in the SSRS2 catalog (Adami+, 2002)
J/ApJS/129/475 : The CNOC2 survey. I. (Yee+, 2000)
J/A+A/342/1 : ESO Slice Project. VI. Groups of Galaxies. (Ramella+ 1999)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Common group name (HHMM+DD) (1)
9- 10 I2 h RAh Right Ascension (B1950)
12- 13 I2 min RAm Right Ascension (B1950)
15- 18 F4.1 s RAs Right Ascension (B1950)
20 A1 --- DE- Sign of the Declination (B1950)
21- 22 I2 deg DEd Declination (B1950)
24- 25 I2 arcmin DEm Declination (B1950)
27- 28 I2 arcsec DEs Declination (B1950)
30- 36 F7.5 --- z Spectroscopic redshift
38- 40 I3 km/s sigma Median velocity dispersion
42- 44 I3 km/s e_sigma Uncertainty in sigma
46- 49 I4 solMass/solLum M/L The virial mass-to-light ratio (2)
51- 55 I5 solMass/solLum e_M/L Uncertainty in M/L (2)
57 I1 --- Nz Number of group members with redshifts
59- 67 E9.2 solMass Mass Group mass (2)
69- 71 I3 % e_Mass Percent uncertainty in Mass (2)
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Note (1): Objects are <[CYM2001] HHMMSS.s+DDMMSS> in Simbad.
Note (2): Assuming H0=100h km/s/Mpc and adopting ΩM=0.2,
ΩΛ=0 as the reference cosmological model.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 20-Sep-2010