J/ApJ/805/65ivo://CDS.VizieR/J/ApJ/805/65doi:10.26093/cds/vizier.18050065CDSTaylor M.A.Puzia T.H.Gomez M.Woodley K.A.2017-06-26T11:50:46Z2015-10-08T13:30:49ZCDS support team

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

cds-question@unistra.frglobular-star-clustersgalaxiesspectroscopyradial-velocitygalaxy-kinematicsWe present a study of the dynamical properties of 125 compact stellar systems (CSSs) in the nearby giant elliptical galaxy NGC 5128, using high-resolution spectra (R~26000) obtained with Very Large Telescope/FLAMES. Our results provide evidence for a new type of star cluster, based on the CSS dynamical mass scaling relations. All radial velocity (v_r_) and line-of-sight velocity dispersion ({sigma}_los_) measurements are performed with the penalized pixel fitting (ppxf) technique, which provided {sigma}_ppxf_ estimates for 115 targets. The {sigma}_ppxf_ estimates are corrected to the 2D projected half-light radii, {sigma}_1/2_, as well as the cluster cores, {sigma}_0_, accounting for observational/aperture effects and are combined with structural parameters, from high spatial resolution imaging, in order to derive total dynamical masses (M_dyn_) for 112 members of NGC5128's star cluster system. In total, 89 CSSs have dynamical masses measured for the first time along with the corresponding dynamical mass-to-light ratios ({sigma}_1/2_). We find two distinct sequences in the {gamma}^dyn^_V_-M_dyn_ plane, which are well approximated by power laws of the forms {gamma}^dyn^_V_{propto}M_dyn_^0.33+/-0.04^ and {gamma}^dyn^_V_{propto}M_dyn_^0.79+/-0.04^. The shallower sequence corresponds to the very bright tail of the globular cluster luminosity function (GCLF), while the steeper relation appears to be populated by a distinct group of objects that require significant dark gravitating components such as central massive black holes and/or exotically concentrated dark matter distributions. This result would suggest that the formation and evolution of these CSSs are markedly different from the "classical" globular clusters in NGC 5128 and the Local Group, despite the fact that these clusters have luminosities similar to the GCLF turnover magnitude. We include a thorough discussion of myriad factors potentially influencing our measurements.2015ApJ...805...65Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/805/65CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/773/L36 : NGC 5128 globular cluster abundances (Colucci+, 2013)J/AJ/143/84 : New candidate globular clusters in NGC 5128 (Harris+, 2012)J/ApJS/197/22 : The Carnegie-Irvine Galaxy Survey (GGS). II. (Li+, 2011)J/ApJS/192/10 : Chandra ACIS survey in 383 nearby galaxies. I. (Liu, 2011)J/ApJ/726/108 : Dispersion-supported stellar systems (Tollerud+, 2011)J/AJ/140/2101 : NGC 5128 globular clusters photometry (Sinnott+, 2010)J/AJ/139/1871 : Kinematics of globulars in NGC 5128 (Woodley+, 2010)J/ApJ/708/1335 : Spectroscopy of globulars in NGC 5128 (Woodley+, 2010)J/ApJ/681/197 : ACS Virgo Cluster Survey. XV (Peng+, 2008)J/MNRAS/386/1443 : 2dF study of globular clusters in NGC 5128 (Beasley+, 2008)J/AJ/134/494 : NGC 5128 GCs UBVRICMT1 phot. + RV (Woodley+, 2007)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/805/65https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/805/65http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/805/65https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/805/65https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/805/65http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/805/65GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/805/65/gc (Star cluster observations, kinematics and structural parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/805/65/gc?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/805/65/gc?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/805/65/gc?GETtext/xml+votable180.050000true201.11845417-42.964711110.0055555555555555566/43262 43263https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/805/65?format=asciiOpticaldefaultJ/ApJ/805/65/gcStar cluster observations, kinematics and structural parametersM/Lhm[0.4/64.5]? The 'half-mass' mass-to-light ratiosolMass/solLumphys.composition.massLightRatiofloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGC[5/441] Cluster identifier (G1)meta.id;meta.mainintRAJ2000[13] Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[42/43] Degree of Declination (J2000)pos.eq.dec;meta.mainRmag[17/20.5] Apparent R band magnitude (1)magphot.mag;em.opt.RfloatVmag[16.8/20.7] Dereddened apparent V band magnitude (2)magphot.mag;em.optfloate_Vmag[0.01/0.2] Uncertainty in Vmagmagstat.error;phot.mag;em.opt.VfloatExp[1200/26400] Total integration timestime.epochintS/N[0.2/11]? Signal-to-Noise ratio (3)stat.snrfloatnullableRgc[1/21.5] Galacto-centric angular radiusarcminphys.angSizefloatRVlt[146/890]? Literature radial velocitykm/sphys.veloc;pos.heliocentricintnullablee_RVlt[1/202]? Uncertainty in RVltkm/sstat.errorintnullabler_RVlt[1/5]? Reference code for RVlt (5)meta.ref;pos.frameintnullableRV[19/836]? Penalized pixel fitting technique radial velocitykm/sphys.veloc;pos.heliocentricintnullablee_RV[0.3/31]? Uncertainty in RVkm/sstat.errorfloatnullablesigma[1/68]? Penalized pixel fitting technique velocity dispersion {sigma}km/sphys.veloc.dispersionfloatnullablee_sigma[0.3/52]? Uncertainty in sigmakm/sstat.errorfloatnullablesig.ap[3.6/68]? Model aperture corrected velocity dispersion {sigma}_ap_ (4)km/sphys.veloc.dispersionfloatnullableE_sig.ap? Upper uncertainty in sig.apkm/sstat.error;stat.maxfloatnullablee_sig.ap? Lower uncertainty in sig.apkm/sstat.errorfloatnullablesig.gl[3.5/62]? Global aperture corrected velocity dispersion {sigma}_gl_km/sphys.veloc.dispersionfloatnullableE_sig.gl[0.02/18]? Upper uncertainty in sig.glkm/sstat.error;stat.maxfloatnullablee_sig.gl[0.07/18]? Lower uncertainty in sig.glkm/sstat.errorfloatnullablesig.0[4/69.2]? Cluster core aperture corrected velocity dispersion {sigma}_0_km/sphys.veloc.dispersionfloatnullableE_sig.0? Upper uncertainty in sig.0km/sstat.error;stat.maxfloatnullablee_sig.0? Lower uncertainty in sig.0km/sstat.errorfloatnullablesig.hl[3.9/66]? Aperature corrected 2D projected half-light radius velocity dispersion {sigma}_1/2_km/sphys.veloc.dispersionfloatnullableE_sig.hl? Upper uncertainty in sig.hlkm/sstat.error;stat.maxfloatnullablee_sig.hl? Lower uncertainty in sig.hlkm/sstat.errorfloatnullableMhm[0.03/7.5]? The 'half-mass' M_1/2_ (6)solMassphys.massfloatnullableE_Mhm? Upper limit uncertainty in MhmsolMassstat.error;stat.maxfloatnullablee_Mhm? Lower limit uncertainty in MhmsolMassstat.errorfloatnullableMdyn[0.07/15.4]? Dynamical masssolMassphys.massfloatnullableE_Mdyn? Upper limit uncertainty in MdynsolMassstat.error;stat.maxfloatnullablee_Mdyn? Lower limit uncertainty in MdynsolMassstat.errorfloatnullableE_M/Lhm? Upper limit uncertainty in M/LhmsolMass/solLumstat.error;stat.maxfloatnullablee_M/Lhm? Lower limit uncertainty in M/LhmsolMass/solLumstat.errorfloatnullableM/Ldyn[0.5/66.7]? Dynamic mass-to-light ratiosolMass/solLumphys.composition.massLightRatiofloatnullableE_M/Ldyn? Upper limit uncertainty in M/LdynsolMass/solLumstat.error;stat.maxfloatnullablee_M/Ldyn? Lower limit uncertainty in M/LdynsolMass/solLumstat.errorfloatnullablerh[0.2/23]? Half light radiuspcphysfloatnullablee_rh? Uncertainty in rhpcstat.errorfloatnullabler_rh? Reference for rh (7)meta.ref;pos.frameintnullablec[0.8/2.5]? Concentration parameterstat.paramfloatnullableNEDDisplay NED datameta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlchar