J/ApJ/882/5ivo://CDS.VizieR/J/ApJ/882/5doi:10.26093/cds/vizier.18820005CDSWilson C.D.Elmegreen B.G.Bemis A.Brunetti N.2021-07-05T08:03:27Z2021-02-24T10:06:57ZCDS support team

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

cds-question@unistra.frgalaxiesinfrared-sourcesinterstellar-mediumco-line-emissiongalaxy-kinematicsmolecular-physicsA new analysis of high-resolution data from the Atacama Large Millimeter/submillimeter Array for five luminous or ultraluminous infrared galaxies gives a slope for the Kennicutt-Schmidt (KS) relation equal to 1.74_-0.07_^+0.09^ for gas surface densities {Sigma}_mol_>10^3^M_{sun}_/pc^2^ and an assumed constant CO-to-H2 conversion factor. The velocity dispersion of the CO line, {sigma}_v_, scales approximately as the inverse square root of {Sigma}_mol_, making the empirical gas scale height determined from H~0.5{sigma}^2^/({pi}G{Sigma}_mol_) nearly constant, 150-190pc, over 1.5 orders of magnitude in {Sigma}_mol_. This constancy of H implies that the average midplane density, which is presumably dominated by CO-emitting gas for these extreme star-forming galaxies, scales linearly with the gas surface density, which in turn implies that the gas dynamical rate (the inverse of the freefall time) varies with {Sigma}_mol_^1/2^, thereby explaining most of the super-linear slope in the KS relation. Consistent with these relations, we also find that the mean efficiency of star formation per freefall time is roughly constant, 5%-7%, and the gas depletion time decreases at high {Sigma}_mol_, reaching only ~16Myr at {Sigma}_mol_~10^4^M_{sun}_/pc^2^. The variation of {sigma}_v_ with {Sigma}_mol_ and the constancy of H are in tension with some feedback-driven models, which predict {sigma}_v_ to be more constant and H to be more variable. However, these results are consistent with simulations in which large-scale gravity drives turbulence through a feedback process that maintains an approximately constant Toomre Q instability parameter.2019ApJ...882....5Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/882/5CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/136/2782 : Star formation efficiency in nearby galaxies (Leroy+, 2008)J/MNRAS/433/2240 : SALT2 parameters & distances for SNe (Ganeshalingam+, 2013)J/ApJ/799/10 : Arp 220 6 and 33GHz images (Barcos-Munoz+, 2015)J/ApJ/860/172 : Cloud-scale molecular gas data in 15 galaxies (Sun+, 2018)J/ApJ/872/16 : Integrated star formation law rev. I. (de los Reyes+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/882/5https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/882/5http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/882/5https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/882/5https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/882/5http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/882/5GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/882/5/table1 ((Ultra-)Luminous IR Galaxies observed with ALMA)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/882/5/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/882/5/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/882/5/table1?GETtext/xml+votable180.050000true260.8414292-0.28360.005555555555555556Cone search capability for table J/ApJ/882/5/table2 (*Binned data used in this paper)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/882/5/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/882/5/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/882/5/table2?GETtext/xml+votable180.050000true156.9634-43.905990.0055555555555555566/8673 19283 31081 38139 43107https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/882/5?format=asciiInfraredRadiodefaultJ/ApJ/882/5/table1(Ultra-)Luminous IR Galaxies observed with ALMADist[44/182] Distance (1)Mpcpos.distance;pos.heliocentricintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameGalaxy namemeta.id;meta.maincharArea[1.1/5.2] Map area (2)kpc**2phys.angSizefloatBeamBeam FWHMarcsecphys.angSize;instr.beamcharsig[0.015/0.1] {sigma}_cont_mJy/beamstat.errorfloatsigCO[0.043/0.18] {sigma}_CO(1-0)_stat.errorfloatPix[345/650] Binned pixel sizepcphys.angSize;instr.pixelintGalAbbreviated galaxy name as in Table 2meta.idcharprimarySimbadSimbad column added by the CDSmeta.ref.urlcharNEDNED column added by the CDSmeta.ref.urlcharLEDAmeta.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.mainJ/ApJ/882/5/table2*Binned data used in this paperrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGalGalaxy identifiermeta.id.part;meta.maincharprimarySeqPixel identifier within Galmeta.id.part;meta.mainintRAJ2000[156.9/346] Right Ascension (J2000) (1)degpos.eq.ra;meta.mainDEJ2000[-55.2/23.6] Declination (J2000) (1)degpos.eq.dec;meta.mainsigv[29/156.2] Observed CO J=1-0 velocity dispersionkm/sphys.veloc.dispersion;spect.linedoublee_sigv[0.7/25.5] Uncertainty on sigvkm/sstat.errordoublelog-MMol[2.4/4] Log of molecular mass surface densitylog(solMass.pc**-2)phys.densitydoublee_log-MMol[0.02/0.03] Uncertainty on log-MMollog(solMass.pc**-2)stat.errordoublelog-SFR[0.1/2.8] Log of star formation rate surface densitylog(solMass.yr**-1.kpc**-2)phys.SFRdoublee_log-SFR[0.01/0.2] Uncertainty on log-SFRlog(solMass.yr**-1.kpc**-2)stat.errordoublelog-tdep[7.2/8.7] Log of depletion timelog(yr)time.scaledoublee_log-tdep[0.03/0.2] Uncertainty on log-tdeplog(yr)stat.errordoublelog-tff[6/7.2] Log of free-fall timescalelog(yr)time.scaledoublee_log-tff[0.02/0.2] Uncertainty on log-tfflog(yr)stat.errordoublelog-eff[-2.2/-0.9] Log of efficiency per tffstat.paramdoublee_log-eff[0.04/0.2] Uncertainty on log-effstat.errordoublelog-H[1.7/2.7] Log of molecular gas scale heightlog(pc)instr.scaledoublee_log-H[0.02/0.3] Uncertainty on log-Hlog(pc)stat.errordouble