J/ApJ/827/33ivo://CDS.VizieR/J/ApJ/827/33doi:10.26093/cds/vizier.18270033CDSJohnson L.C.Seth A.C.Dalcanton J.J.Beerman L.C.Fouesneau M.,Lewis A.R.Weisz D.R.Williams B.F.Bell E.F.Dolphin A.E.,Larsen S.S.Sandstrom K.Skillman E.D.2017-02-09T14:49:39Z2016-12-06T10:30:38ZCDS support team

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

cds-question@unistra.frgalaxiesopen-star-clusterssurveysWe use the Panchromatic Hubble Andromeda Treasury survey data set to perform spatially resolved measurements of star cluster formation efficiency ({Gamma}), the fraction of stellar mass formed in long-lived star clusters. We use robust star formation history and cluster parameter constraints, obtained through color-magnitude diagram analysis of resolved stellar populations, to study Andromeda's cluster and field populations over the last ~300Myr. We measure {Gamma} of 4%-8% for young, 10-100Myr-old populations in M31. We find that cluster formation efficiency varies systematically across the M31 disk, consistent with variations in mid-plane pressure. These {Gamma} measurements expand the range of well-studied galactic environments, providing precise constraints in an HI-dominated, low-intensity star formation environment. Spatially resolved results from M31 are broadly consistent with previous trends observed on galaxy-integrated scales, where {Gamma} increases with increasing star formation rate surface density ({Sigma}_SFR_). However, we can explain observed scatter in the relation and attain better agreement between observations and theoretical models if we account for environmental variations in gas depletion time ({tau}_dep_) when modeling {Gamma}, accounting for the qualitative shift in star formation behavior when transitioning from a H_2_-dominated to a HI-dominated interstellar medium. We also demonstrate that {Gamma} measurements in high {Sigma}_SFR_ starburst systems are well-explained by {tau}_dep_-dependent fiducial {Gamma} models.2016ApJ...827...33Jhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/827/33CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/MNRAS/451/724 : PHAT. XIII. M31 Cepheid P-L relation (Wagner-Kaiser+, 2015)J/ApJS/215/9 : PHAT X. UV-IR photometry of M31 stars (Williams+, 2014)J/ApJ/758/133 : Metallicity profile of M31 HII regions and PNe (Sanders+, 2012)J/ApJ/752/95 : PHAT stellar cluster survey. I. Year 1 (Johnson+, 2012)J/A+A/529/A25 : Photom. of star clusters in 5 nearby gal. (Silva-Villa+, 2011)J/AJ/140/1194 : FUV/HI relations in nearby galaxies (Bigiel+, 2010)J/AJ/136/2782 : Star formation efficiency in nearby galaxies (Leroy+, 2008)J/ApJ/762/123 : PHAT. IV. Initial Mass Function (Weisz+, 2013)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/827/33https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/827/33http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/827/33https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/827/33https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/827/33http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/827/33GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/827/33/table4 (Cluster fitting results)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/827/33/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/827/33/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/827/33/table4?GETtext/xml+votable180.050000true11.3665138941.701013060.0055555555555555566/2623 2666 2709 2752https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/827/33?format=asciidefaultJ/ApJ/827/33/table4Cluster fitting resultsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintAPID[2/6182] Cluster Identification Number (1)meta.id;meta.mainintRegIDRegion Identification (2)meta.id;obs.fieldcharlogAge[7/9] Best Log Agelog(yr)time.age;meta.modelledfloatb_logAge[6.6/8.4] 16th Percentile log Agelog(yr)time.agefloatB_logAge[7/9.6] 84th Percentile log Agelog(yr)time.agefloatlogMass[2.2/4.4] Best Log Masslog(solMass)phys.massfloatb_logMass[0/4.3] 16th Percentile log Masslog(solMass)phys.massfloatB_logMass[2.3/5] 84th Percentile log Masslog(solMass)phys.massfloat_RAPositions from Andromeda Project cluster catalog (Johnson+, 2015, J/ApJ/802/127) (right ascension part)degpos.eq.ra;meta.main_DEPositions from Andromeda Project cluster catalog (Johnson+, 2015, J/ApJ/802/127) (declination part)degpos.eq.dec;meta.main