J/ApJ/646/133ivo://CDS.VizieR/J/ApJ/646/133doi:10.26093/cds/vizier.16460133CDSMulchaey J.S.Lubin L.M.Fassnacht C.Rosati P.Jeltema T.E.2017-12-15T10:55:16Z2008-10-19T17:48:48ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frgalaxy-clustersredshiftedphotometryWe present spectroscopic confirmation of nine moderate-redshift galaxy groups and poor clusters selected from the ROSAT Deep Cluster Survey. The groups span the redshift range and have between 4 and 20 confirmed members. The velocity dispersions of these groups range from ~125 to 650km/s. Similar to X-ray groups at low redshift, these systems contain a significant number of early-type galaxies. Therefore, the trend for X-ray-luminous groups to have high early-type fractions is already in place by at least z~0.5. In four of the nine groups, the X-ray emission is clearly peaked on the most luminous early-type galaxy in the group. However, in several cases the central galaxy is composed of multiple luminous nuclei, suggesting that the brightest group galaxy may still be undergoing major mergers. In at least three (and possibly five) of the groups in our sample, a dominant early-type galaxy is not found at the center of the group potential. This suggests that many of our groups are not dynamically evolved despite their high X-ray luminosities. While similar systems have been identified at low redshift, the X-ray luminosities of the intermediate-redshift examples are 13 orders of magnitude higher than those of their low-redshift counterparts. We suggest that this may be evidence for group downsizing: while massive groups are still in the process of collapsing and virializing at intermediate redshifts, only low-mass groups are in the process of forming at the present day.2006ApJ...646..133Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/646/133CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/84 : Groups of Galaxies. III. The CfA Survey (Geller+ 1983)VII/89 : Compact groups of compact galaxies (Shakhbazian+ 1973-1979)J/A+AS/100/47 : Lyon Groups of Galaxies (Garcia 1993)J/A+AS/117/39 : Hickson Compact Groups of Galaxies I. (Allam+, 1996)J/AJ/113/483 : Groups of Galaxies (Ramella+ 1997)J/A+AS/130/341 : Groups of Galaxies in PPS (Trasarti-Battistoni 1998)J/AJ/116/1573 : Redshift Survey Compact Groups (Barton+, 1998)J/A+A/342/1 : ESO Slice Project. VI. Groups of Galaxies. (Ramella+ 1999)J/AN/321/101 : Compact groups of galaxies in LCRS (Allam+, 2000)J/ApJ/534/114 : RASSCALS: X-ray and optical study (Mahdavi+, 2000)J/A+A/381/420 : Group of Galaxies in the SSRS2 catalog (Adami+, 2002)J/AJ/125/1660 : Distant compact groups from DPOSS (Iovino+, 2003)J/AJ/127/1811 : Catalog of SDSS compact groups of galaxies (Lee+, 2004)J/AJ/130/425 : Catalog of distant compact groups of galaxiesJ/AN/327/365 : Clusters and groups of galaxies in 2dF (Tago+, 2006)J/A+A/479/927 : Group of galaxies in SDSS 5 (Tago+, 2008)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/646/133https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/646/133http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/646/133https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/646/133https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/646/133http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/646/133GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/646/133/table1 (*Photometric and spectroscopic results)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/646/133/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/646/133/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/646/133/table1?GETtext/xml+votable180.050000true32.54125-39.44408330.005555555555555556Cone search capability for table J/ApJ/646/133/table2 (Group properties)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/646/133/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/646/133/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/646/133/table2?GETtext/xml+votable180.050000true32.6037083-39.49363890.0055555555555555565/7031 8590 6/7896 10218 10484 10936 10938 23223 26443 35272https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/646/133?format=asciiOpticaldefaultJ/ApJ/646/133/table1*Photometric and spectroscopic resultsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainRmag? The R band magnitudemagphot.mag;em.opt.Rfloatnullablef_Rmag[1] Composed Rmag (1)meta.codecharzSpectroscopic redshiftsrc.redshiftfloate_zError in zstat.error;src.redshiftfloatztypeRedshift type (absorption and/or emission)meta.notecharJ/ApJ/646/133/table2Group propertiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGroupGroup name (RX JHHMM.m+DDMM)meta.id;meta.maincharRAJ2000Right Ascension J2000pos.eq.ra;meta.mainDEJ2000Declination J2000pos.eq.dec;meta.mainzGroup redshiftsrc.redshiftfloatNmNumber of members in the groupmeta.numberintsigVelocity dispersion (Gaussian estimator)km/sphys.veloc.dispersionintE_sigError on sig (upper limit)km/sstat.error;stat.maxinte_sigError on sig (lower limit)km/sstat.errorintETf[0,1] Fraction of early-type galaxiesstatfloatNotesRemarks concerning the group (BGG = brightest group galaxy)meta.notecharSimbadSimbad column added by the CDSchar