J/ApJ/768/137ivo://CDS.VizieR/J/ApJ/768/137doi:10.26093/cds/vizier.17680137CDSYoon S.-J.Sohn S.T.Kim H.-S.Chung C.Cho J.Lee S.-Y.,Blakeslee J.P.2017-09-19T14:23:50Z2015-01-08T10:39:13ZCDS support team

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

cds-question@unistra.frglobular-star-clustershst-photometryColor distributions of globular clusters (GCs) in most massive galaxies are bimodal. Assuming linear color-to-metallicity conversions, bimodality is viewed as the presence of merely two GC subsystems with distinct metallicities, which serves as a critical backbone of various galaxy formation theories. Recent studies, however, revealed that the color-metallicity relations (CMRs) often used to derive GC metallicities (e.g., CMRs of g-z, V-I, and C-T_1_) are in fact inflected. Such inflection can create bimodal color distributions if the underlying GC metallicity spread is simply broad as expected from the hierarchical merging paradigm of galaxy formation. In order to test the nonlinear-CMR scenario for GC color bimodality, the u-band photometry is proposed because the u-related CMRs (e.g., CMRs of u-g and u-z) are theoretically predicted to be least inflected and most distinctive among commonly used optical CMRs. Here, we present Hubble Space Telescope (HST)/WFC3 F336W (u-band) photometry of the GC system in M84, a giant elliptical in the Virgo galaxy cluster. Combining the u data with the existing HST ACS/WFC g and z data, we find that the u-z and u-g color distributions are different from the g-z distribution in a very systematic manner and remarkably consistent with our model predictions based on the nonlinear-CMR hypothesis. The results lend further confidence to the validity of the nonlinear-CMR scenario as an explanation for GC color bimodality. There are some GC systems showing bimodal spectroscopic metallicity, and in such systems the inflected CMRs often create stronger bimodality in the color domain.2013ApJ...768..137Yhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/768/137CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/hst : HST Archived Exposures Catalog (STScI, 2007)J/ApJ/763/40 : UBVI phot. of GCs in the Fornax galaxy cluster (Kim+, 2013)J/MNRAS/426/1475 : CaT in 903 globular clusters (Usher+, 2012)J/MNRAS/416/155 : Globular clusters in 5 early-type galaxies (Faifer+, 2011)J/A+A/525/A19 : Phot. of globulars in early galaxies (Chies-Santos+, 2011)J/ApJ/743/149 : Color-metallicity relations. Paper II: M87 GCs (Yoon+, 2011)J/ApJS/180/54 : GC candidates in ACS Virgo survey. (Jordan+, 2009)J/MNRAS/389/1150 : Spitzer phot. of globulars in 2 galaxies (Spitler+, 2008)J/ApJS/171/101 : GCs in the ACS Virgo cluster survey (Jordan+, 2007)J/ApJS/154/509 : ACS Virgo Cluster Survey. II. (Jordan+, 2004)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/768/137https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/768/137http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/768/137https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/768/137https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/768/137http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/768/137GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/768/137/table1 (The u-, g-, and z-band mags and their observational errors for the M84 globular cluster candidates)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/768/137/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/768/137/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/768/137/table1?GETtext/xml+votable180.050000true186.2654719412.885701110.0055555555555555566/277732.1350832807657816e-19 6.371754394130019e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/768/137?format=asciiOpticaldefaultJ/ApJ/768/137/table1The u-, g-, and z-band mags and their observational errors for the M84 globular cluster candidatesSeq[1/390] Globular cluster index numbermeta.id;meta.mainintprimaryRAJ2000Right Ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.mainumag[22.5/27.9] HST/WFC3 F336W band extinction corrected AB magnitudemagphot.mag;em.opt.Ufloate_umag[0.008/0.5] Error in umagmagstat.error;phot.mag;em.opt.UfloatgmagHST/ACS F475W band extinction corrected AB magnitude from Jordan et al. 2009 (J/ApJS/180/54)magphot.mag;em.opt.Bfloate_gmagError in gmagmagstat.error;phot.mag;em.opt.Bfloatzmag[19.5/25.2] HST/ACS F850LP band extinction corrected AB magnitude from Jordan et al. 2009 (J/ApJS/180/54)magphot.mag;em.opt.Ifloate_zmag[0.005/0.2] Error in zmagmagstat.error;phot.mag;em.opt.IfloatJ09Display the data from the ACS Virgo survey (Jordan+, 2009, J/ApJS/180/54meta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlchar