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J/AJ/154/96      Groups of galaxies from from SDSS-DR7      (de Carvalho+, 2017)

Investigating the relation between galaxy properties and the Gaussianity of the velocity distribution of groups and clusters. de Carvalho R.R., Ribeiro A.L.B., Stalder D.H., Rosa R.R., Costa A.P., Moura T.C. <Astron. J., 154, 96-96 (2017)> =2017AJ....154...96D (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Redshifts ; X-ray sources Keywords: evolution - galaxies: clusters: general - galaxies: formation - galaxies: groups: general Abstract: We investigate the dependence of stellar population properties of galaxies on group dynamical stage for a subsample of the Yang catalog. We classify groups according to their galaxy velocity distribution into Gaussian (G) and Non-Gaussian (NG). Using two totally independent approaches, we have shown that our measurement of Gaussianity is robust and reliable. Our sample covers Yang's groups in the redshift range 0.03≤z≤0.1, with mass ≥1014M. The new method, called Hellinger Distance, to determine whether a group has a velocity distribution Gaussian or NG is very effective in distinguishing between the two families. NG groups present halo masses higher than the G ones, confirming previous findings. Examining the skewness and kurtosis of the velocity distribution of G and NG groups, we find that faint galaxies in NG groups are mainly infalling, for the first time, into the groups. We show that considering only faint galaxies in the outskirts; those in NG groups are older and more metal-rich than those in G groups. Also, examining the Projected Phase Space of cluster galaxies, we see that bright and faint galactic systems in G groups are in dynamical equilibrium-which does not seem to be the case in NG groups. These findings suggest that NG systems have a higher infall rate, assembling more galaxies that have experienced preprocessing before entering the group. Description: To study the updated group catalog of Yang et al. (2007ApJ...671..153Y), we select galaxies from SDSS-DR7 (see Adelman-McCarthy et al. 2009, Cat. II/294) with 0.03≤z≤0.1 and r magnitudes brighter than 17.78, which is the spectroscopic completeness limit of the survey, guaranteeing that we probe the luminosity function up to M*+1 for all systems. The lower limit in redshift is imposed to avoid aperture effects in the stellar population parameters measured within a fixed aperture of 3arcsec (diameter) used in the SDSS. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 49 319 Group sample
See also: V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015) II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009) J/ApJ/776/71 : Galaxies in groups along the cosmic web. I. (Carollo+, 2013) J/A+A/542/A36 : Rich clusters from SDSS DR8 (Einasto+, 2012) J/A+A/540/A123 : Galaxy clusters from SDSS DR8 (Einasto+, 2012) J/A+A/425/367 : REFLEX Galaxy Cluster Survey catalogue (Boehringer+, 2004) J/ApJS/129/435 : NORAS galaxy cluster survey. I. (Bohringer+, 2000) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 6 I6 --- Yang [2/665] Identification number of the galaxy group in Yang et al. 2007ApJ...671..153Y 8- 15 F8.4 deg RAdeg Right Ascension in decimal degrees (J2000) 17- 24 F8.4 deg DEdeg Declination in decimal degrees (J2000) 26- 30 F5.3 --- <z> [0.03/0.1] Mean redshift of the group (1) 32- 36 F5.2 [Msun] logM200 [13.3/15.8] Log of dynamical mass (M200) (2) 38- 41 F4.2 Mpc R200 [0.45/2.73] Virial radius (R200) (2) 43- 45 I3 --- N200 [20/525] Number of member galaxies within R200, down to the limiting magnitude of the catalog, NR200 (3) 47 A1 --- BAX [NY] Group having X-ray counterparts in BAX ( (4) 49 A1 --- N/R [NY] Group having X-ray counterparts in NORAS and/or REFLEX (5)
Note (1): As measured with the shift-gapper technique. Note (2): As obtained through the shift-gapper algorithm and dynamical analysis. Note (3): Only systems richer than 20 galaxies (within R200) are used in this work (see Section 3.1 for more details on why we choose this lower limit). Note (4): BAX is an online research database containing information on all galaxy clusters with X-ray observations to date. Note (5): NORAS (Northern ROSAT All-Sky; Bohringer et al. 2000, Cat. J/ApJS/129/435), and REFLEX (ROSAT-ESO Flux-limited X-ray; Bohringer et al. 2004, Cat. J/A+A/425/367).
History: From electronic version of the journal
(End) Sylvain Guehenneux [CDS] 15-Nov-2017
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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