J/ApJ/821/114ivo://CDS.VizieR/J/ApJ/821/114doi:10.26093/cds/vizier.18210114CDSHuang S.Ho L.C.Peng C.Y.Li Z.-Y.Barth A.J.2017-12-06T07:39:06Z2016-08-25T09:43:51ZCDS support team

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

cds-question@unistra.frgalaxiesphotometrygalaxy-classification-systemssurveysMany recent observations and numerical simulations suggest that nearby massive, early-type galaxies (ETGs) were formed through a "two-phase" process. In the proposed second phase, the extended stellar envelope was accumulated through many dry mergers. However, details of the past merger history of present-day ellipticals, such as the typical merger mass ratio, are difficult to constrain observationally. Within the context and assumptions of the two-phase formation scenario, we propose a straightforward method, using photometric data alone, to estimate the average mass ratio of mergers that contributed to the build-up of massive elliptical galaxies. We study a sample of nearby massive elliptical galaxies selected from the Carnegie-Irvine Galaxy Survey, using two-dimensional analysis to decompose their light distribution into an inner, denser component plus an extended, outer envelope, each having a different optical color. The combination of these two substructures accurately recovers the negative color gradient exhibited by the galaxy as whole. The color difference between the two components (<{Delta}(B-V)>~0.10mag; <{Delta}(B-R)>~0.14mag), based on the slope of the M*-color relation for nearby ETGs, can be translated into an estimate of the average mass ratio of the mergers. The rough estimate, 1:5 to 1:10, is consistent with the expectation of the two-phase formation scenario, suggesting that minor mergers were largely responsible for building up the outer stellar envelopes of present-day massive ellipticals. With the help of accurate photometry, large sample sizes and more choices of colors promised by ongoing and future surveys, the approach proposed here can provide more insights into the growth of massive galaxies during the last few Gyr.2016ApJ...821..114Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/821/114CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/563/A92 : VIPERS: galaxy colours and luminosity function (Fritz+, 2014)J/ApJS/210/3 : SDSS bulge, disk & stellar mass estimates (Mendel+, 2014)J/MNRAS/435/623 : Multiwavelength measurement of galaxy structure (Vika, 2013)J/ApJ/766/109 : Color/age/metallicity gradients of E galaxies (Kim+, 2013)J/ApJ/749/121 : Surface brightness profiles of z=2 galaxies (Szomoru+, 2012)J/ApJS/197/22 : The Carnegie-Irvine Galaxy Survey (GGS). II. (Li+, 2011)J/ApJS/197/21 : The Carnegie-Irvine Galaxy Survey (CGS). I. (Ho+, 2011)J/ApJS/196/11 : Bulge+disk decompositions of SDSS galaxies (Simard+, 2011)J/A+A/525/A157 : SDSS automated morphology classif. (Huertas-Company+, 2011)J/A+A/478/353 : Structural properties of disk galaxies (Mendez-Abreu+, 2008)J/AJ/131/1288 : Composite spectra of early-type galaxies (Bernardi+, 2006)J/A+A/441/451 : UBVRIJHK photometry of E-type galaxies (Michard+, 2005)J/AJ/129/2138 : Centers of early-type galaxies with HST (Lauer+, 2005)J/AJ/100/1091 : UBR photometry of 39 elliptical galaxies (Peletier+ 1990)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/821/114https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/821/114http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/821/114https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/821/114https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/821/114http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/821/114GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/821/114/table1 (Summary of color measurements for three-component Sersic models)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/821/114/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/821/114/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/821/114/table1?GETtext/xml+votable180.050000true300.8626083-55.94719440.0055555555555555566/17472 17605 17606 22746 24733 24951 25383 25762 26125 34535 34540 35928 36152 36153 36156 36172 36247 36621 36623 36632 36785 37266 37560 38347 38621 38693 38704 38853 39858 39982 40252 40294 40321 43214 43232 43503 43626 43627 43700 43828 43877 43891 43941 44000 44247 44629 44995 45821 46164 46389 46568 46608 46618 47190 47253 47383 47386 47397 48160https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/821/114?format=asciiOpticaldefaultJ/ApJ/821/114/table1Summary of color measurements for three-component Sersic modelsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameGalaxy namemeta.id;meta.maincharlogMTot[10.3/11.8] Total stellar mass of the galaxylog(solMass)phys.massfloate_logMTot[0.04/0.3] Uncertainty in logMTotlog(solMass)stat.errorfloatlogMIn[9.9/11.6] Stellar mass of the inner componentlog(solMass)phys.massfloatlogMOut[9.8/11.7] Stellar mass of the outer componentlog(solMass)phys.massfloatColType of color (B i-V i or B i-R i) (1)meta.code;instr.filtercharf_ColFlag on color ("free" or "fixed") (1)meta.codecharCen[0.6/2.3] Color of the center componentmagphot.color;em.opt.B;em.opt.VfloatInter[0.5/2.1] Color of the intermediate componentmagphot.color;em.opt.B;em.opt.VfloatOuter[0.5/2] Color of the outer componentmagphot.color;em.opt.B;em.opt.VfloatInner[0.6/2.1] Color of the inner componentmagphot.color;em.opt.B;em.opt.VfloatdCol[-0.09/0.4] Color difference between the inner and outer componentsmagphot.mag;arith.difffloatSimbadSimbad column added by the CDSmeta.ref.urlcharNEDSimbad column added by the CDSmeta.ref.urlcharLEDASimbad column added by the CDSmeta.ref.urlchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main