J/A+A/712/A24ivo://CDS.VizieR/J/A+A/712/A24CDSHe H.Leroy A.K.Rosolowsky E.Hughes A.Sun J.Machado J.Bigiel F.,Barnes A.Bazzi Z.Cao Y.Chevance M.Colombo D.Glover S.C.O.,Henshaw J.D.Koch E.W.Meidt S.E.Pan H.Saito T.Sarbadhicary S.K.,Schinnerer E.Smith R.J.Usero A.Weinberg D.H.Williams T.G.2026-07-30T12:39:05Z2026-07-30T13:38:32ZCDS support team

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

cds-question@unistra.frgalaxiesgalaxy-classification-systemsastronomical-modelsThe spatial distribution of giant molecular clouds (GMCs) at sub-kiloparsec scales encodes information about cloud formation and evolution. However, we still lack a general quantitative characterisation of molecular gas structure at this scale. We aim to provide a quantitative description of molecular gas structure at 150-1000pc for a typical star-forming main sequence galaxy. We analyse how GMCs cluster together and how CO emission is spatially correlated with bright GMCs using a sample of 8984 GMCs from 40 galaxies observed by PHANGS-ALMA. We homogenized our data to a common spatial resolution of 150pc and a mass sensitivity of 2.5M_{sun}_/pc^2^ to remove observational bias. We then calculated the nearest neighbour distances, neighbour number density, and two-point correlation functions (2PCFs) for the catalogued GMCs in each galaxy. When analysing the 2PCFs, we generated several control samples that reflect different null hypotheses on large spatial scales. We stacked integrated intensity CO emission profiles around the position of catalogued GMCs to probe the gas distribution on scales between the observational resolution and the typical GMC-GMC spacing. Our measurements of cloud spacing and the number of neighbours show that GMC clustering follows the large-scale gas distribution. Once we accounted for this contribution, the peak excess clustering relative to the null hypothesis in the 2PCF dropped from 1+{imega}~2.3 to 1.3, with the power-law slope flattened from -0.25 to 0. Stacks of CO intensity around local maxima show a strong clustering signal on scales smaller than the typical GMC-GMC separation. We show that this is largely the same signal captured by the "GMC size" measured by CPROPS, with an additional ~20% of the flux in an extended component beyond 500 pc. We find that our stacked profiles can be fit with a double Gaussian function plus a constant offset. The broad Gaussian component accounts for 70% of the over-density power above the constant background and is stronger around massive and gravitationally bound GMCs. Our measurements yield a general statistical description of the structure of CO emission from ~150pc to galactic scales that can serve as a benchmark for simulations of molecular cloud formation and destruction in galaxy disks. Our results indicate that galactic structure exerts a strong influence on the GMC distribution in galaxy disks and that the formation of massive gravitationally bound GMCs is related to strong local gas clustering.2026A&A...712A..24Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/712/A24CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/712/A24https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/712/A24http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/712/A24https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/712/A24https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/712/A24http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/712/A24GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/712/A24/sources (List of studied galaxies)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/712/A24/sources?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/712/A24/sources?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/712/A24/sources?GETtext/xml+votable180.050000true52.8807917-51.90486110.0055555555555555566/4511 16441 16655 18398 22751 24912 25135 25762 25790 26119 26271 27030 27514 27735 27765 27861 27937-27938 27942 27944 28015 28167 28200 33176 33654 33954 34272 34910 35536 35993 38390 38655 38832 43262 43339 43881 46481 46495 46519https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/712/A24?format=asciiOpticaldefaultJ/A+A/712/A24/sourcesList of studied galaxiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGalaxyGalaxy namemeta.id;meta.maincharRAJ2000Simbad right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Simbad declination (J2000)pos.eq.dec;meta.mainSimbadSimbad column added by the CDSmeta.ref.urlcharJ/A+A/712/A24/tableb1Two-point correlation functions of individual galaxiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGalaxyGalaxy namemeta.id;meta.maincharn_Galaxy[*] Note on Galaxymeta.notecharDsepThe log10 value of the separation distance between giant molecular cloudslog(pc)pos.distancedoubleRealvsFlat? The log10 value of the two point correlation amplitude with 'Flat' control median valuestat.fit.paramdoublenullableb_RealvsFlat? The log10 value of the two correlation lower limit with 'Flat' controlstat.correlationdoublenullablen_b_RealvsFlat[I] I for infinitymeta.notecharB_RealvsFlat? The log10 value of the two correlation upper limit with 'Flat' controlstat.correlationdoublenullablen_B_RealvsFlat[I] I for infinitymeta.notecharRealvsExp? The log10 value of the two point correlation amplitude with 'Exp' control median valuestat.fit.paramdoublenullableb_RealvsExp? The log10 value of the two correlation lower limit with 'Exp' controlstat.correlationdoublenullablen_b_RealvsExp[I] I for infinitymeta.notecharB_RealvsExp? The log10 value of the two correlation upper limit with 'Exp' controlstat.correlationdoublenullablen_B_RealvsExp[I] I for infinitymeta.notecharRealvsRad? The log10 value of the two point correlation amplitude with 'Rad' control median valuestat.fit.paramdoublenullableb_RealvsRad? The log10 value of the two correlation lower limit with 'Rad' controlstat.correlationdoublenullablen_b_RealvsRad[I] I for infinitymeta.notecharB_RealvsRad? The log10 value of the two correlation upper limit with 'Rad' controlstat.correlationdoublenullablen_B_RealvsRad[I] I for infinitymeta.notecharRealvsIco? The log10 value of the two point correlation amplitude with 'Ico' controlstat.fit.paramdoublenullableb_RealvsIco? The log10 value of the two correlation lower limit with 'Ico' controlstat.correlationdoublenullablen_b_RealvsIco[I] I for infinitymeta.notecharB_RealvsIco? The log10 value of the two correlation upper limit with 'Ico' controlstat.correlationdoublenullablen_B_RealvsIco[I] I for infinitymeta.notechar