J/MNRAS/505/4048ivo://CDS.VizieR/J/MNRAS/505/4048doi:10.26093/cds/vizier.75054048CDSLiu L.Bureau M.Blitz L.Davis T.A.Onishi K.Smith M.North E.,Iguchi S.2026-03-03T20:03:45Z2024-06-10T12:46:53ZCDS support team

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

cds-question@unistra.frradio-galaxiesinterstellar-mediumh-ii-regionsmolecular-cloudsmolecular-physicsspectroscopymillimeter-astronomysubmillimeter-astronomyphotometryWe present high spatial resolution (~= 12 pc) Atacama Large Millimeter/submillimeter Array 12CO(J = 3-2) observations of the nearby lenticular galaxy NGC 4429. We identify 217 giant molecular clouds within the 450 pc radius molecular gas disc. The clouds generally have smaller sizes and masses but higher surface densities and observed linewidths than those of Milky Way disc clouds. An unusually steep size-linewidth relation ({sigma}{prop.to}R_c_^0.8^) and large cloud internal velocity gradients (0.05-0.91 km/s/pc) and observed virial parameters (<{alpha}_obs,vir_> ~= 4.0) are found, which appear due to internal rotation driven by the background galactic gravitational potential. Removing this rotation, an internal virial equilibrium appears to be established between the self-gravitational (Usg) and turbulent kinetic (Eturb) energies of each cloud, i.e. <{alpha}_sg,vir_> ~ 2E_turb_/|U_sg_| ~ 1.3. However, to properly account for both self and external gravity (shear and tidal forces), we formulate a modified virial theorem and define an effective virial parameter {alpha}_eff,vir_ ~ {alpha}_sg,vir_+E_ext_/|U_sg_| (and associated effective velocity dispersion). The NGC 4429 clouds then appear to be in a critical state in which the self-gravitational energy and the contribution of external gravity to the cloud's energy budget (Eext) are approximately equal, i.e. E_ext_/|U_sg_| ~= 1. As such, <{alpha}_eff,vir_> ~= 2.2 and most clouds are not virialized but remain marginally gravitationally bound. We show this is consistent with the clouds having sizes similar to their tidal radii and being generally radially elongated. External gravity is thus as important as self-gravity to regulate the clouds of NGC 4429.2021MNRAS.505.4048Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/505/4048CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/505/4048https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/505/4048http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/505/4048https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/505/4048https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/505/4048http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/505/4048GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/505/4048/table1 (*Observed properties of the clouds in NGC 4429)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/505/4048/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/505/4048/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/505/4048/table1?GETtext/xml+votable180.050000true186.85916711.107750.0055555555555555566/27764https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/505/4048?format=asciiMillimeterRadiodefaultJ/MNRAS/505/4048/table1*Observed properties of the clouds in NGC 4429recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDGMC Cloud identifier number (ID)meta.id;meta.mainintRAJ2000Right ascension (RAh) (J2000)pos.eq.ra;meta.mainDEJ2000Declination (DEd) (J2000)pos.eq.dec;meta.mainVlsrLocal standard of rest velocity (Vlsr)km/sphys.veloc;pos.lsrfloatRc? Cloud radius computed with equation 2 section 3.1.2 (R)pcphys.size.radiusfloatnullablee_Rc? Mean error of Rc (d_R)pcstat.errorfloatnullablesigmaObserved velocity dispersion computed with equation 3 section 3.1.3 (sigmaobs,los)km/sphys.veloc.dispersionfloate_sigmaMean error of sigma (d_sigmaobs,los)km/sstat.errorfloatSimbadSimbad column added by the CDSmeta.ref.urlchare_sigmagsMean error of sigmags (d_sigmags,los)km/sstat.errorfloatsigmagsGradient-subtracted velocity dispersion derived via the same bootstrapping technique see section 3.1.8 (sigmags,los)km/smeta.ref;pos.framefloatLCOThe CO(3-2) luminosity of each cloud computed with the equation 4 section 3.1.4 (LCO3-2)10000K.km.s**-1.pc**2phys.luminosityfloate_LCOMean error of LCO (d_LCO3-2)10000K.km.s**-1.pc**2stat.errorfloatMgasCloud gaseous mass of each cloud computed with the equation 6 section 3.1.5 (Mgas) (1)100000solMassphys.massfloate_MgasMean error of Mgas (d_Mgas)100000solMassstat.errorfloatTmaxPeak intensity temperature (Tmax)Kphys.temperaturefloatomega? Measured angular velocity (omega)km.s**-1.pc**-1phys.veloc.angfloatnullablee_omega? Mean error of omega (d_omega)km.s**-1.pc**-1stat.errorfloatnullablePA? Position angle of the rotation axis (phirot)degpos.posAngintnullablee_PA? Mean error on PA (d_phirot)degstat.errorintnullableRgalThe deprojected distance of a cloud from the centre of the galaxy see section 3.1.7 (Rgal)pcpos.distanceintJ/MNRAS/505/4048/table3*Derived properties of the clouds in NGC 4429recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDGMC Cloud identifier number (ID)meta.id;meta.mainintOmega0The circular orbital angular velocity at the cloud's CoM (Omega0)km.s**-1.pc**-1phys.velocfloate_Omega0Mean error of Omega0 (d_Omega0)km.s**-1.pc**-1stat.errorfloatT0The tidal acceleration parameter at cloud's CoM (T0) (1)km**2.s**-2.pc**-2stat.fit.paramfloate_T0Mean error of T0 (d_T0)km**2.s**-2.pc**-2stat.errorfloatsigmaeff? The effective linewidth or velocity dispersion (sigmaeff,los) (2)km/sspect.line.widthfloatnullablee_sigmaeff? Mean error on sigmaeff (d_sigmaeff,los)km/sstat.errorfloatnullablelog(rho)The stellar mass volume density at the cloud's CoM (3)log(solMass.pc**-3)meta.bib.volumefloat