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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
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:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 71 190 The rzmax=5h-1Mpc, rpmax=0.25h-1Mpc groups
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
Bytes Format Units Label Explanations
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)
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.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 20-Sep-2010
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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