J/AJ/146/150ivo://CDS.VizieR/J/AJ/146/150doi:10.26093/cds/vizier.51460150CDSCaldu-Primo A.Schruba A.Walter F.Leroy A.Sandstrom K.,de Blok W.J.G.Ianjamasimanana R.Mogotsi K.M.2018-01-08T06:38:12Z2014-07-23T13:59:41ZCDS support team

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

cds-question@unistra.frgalaxiesgalaxy-kinematicsWe present a comprehensive study of the velocity dispersion of the atomic (HI) and molecular (H_2_) gas components in the disks (R{<~}R_25_) of a sample of 12 nearby spiral galaxies with moderate inclinations. Our analysis is based on sensitive high-resolution data from the THINGS (atomic gas) and HERACLES (molecular gas) surveys. To obtain reliable measurements of the velocity dispersion, we stack regions several kiloparsecs in size, after accounting for intrinsic velocity shifts due to galactic rotation and large-scale motions. We stack using various parameters: the galactocentric distance, star formation rate surface density, HI surface density, H_2_ surface density, and total gas surface density. We fit single Gaussian components to the stacked spectra and measure median velocity dispersions for HI of 11.9+/-3.1km/s and for CO of 12.0+/-3.9km/s. The CO velocity dispersions are thus, surprisingly, very similar to the corresponding ones of HI, with an average ratio of {sigma}_HI_/{sigma}_CO_=1.0+/-0.2 irrespective of the stacking parameter. The measured CO velocity dispersions are significantly higher (factor of ~2) than the traditional picture of a cold molecular gas disk associated with star formation. The high dispersion implies an additional thick molecular gas disk (possibly as thick as the HI disk). Our finding is in agreement with recent sensitive measurements in individual edge-on and face-on galaxies and points toward the general existence of a thick disk of molecular gas, in addition to the well-known thin disk in nearby spiral galaxies.2013AJ....146..150Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/146/150CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/136/2563 : HI Nearby Galaxy Survey, THINGS (Walter+, 2008)J/ApJS/173/185 : GALEX ultraviolet atlas of nearby galaxies (Gil de Paz+, 2007)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/146/150https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/146/150http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/146/150https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/146/150https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/146/150http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/146/150GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/146/150/table1 (Properties of the galaxies used in this study)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/146/150/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/146/150/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/146/150/table1?GETtext/xml+votable180.050000true24.1740515.78346110.0055555555555555566/2320 4511 5715 7602 7743 10841 10856 11027 11434 15592 18398 27514https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/146/150?format=asciiOpticaldefaultJ/AJ/146/150/table1Properties of the galaxies used in this studyrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNGCGalaxy NGC numbermeta.id;meta.mainintprimaryNpNumber of points in the velocity profile (table5)meta.numberintnullableDistDistanceMpcpos.distance;pos.heliocentricfloati[0/90] Inclinationdegsrc.orbital.inclinationintPA[0/360] Position angledegpos.posAngintRadOptical radius R_25_kpcphys.size.radiusfloatRes[0.2/0.7] Resolutionkpcpos.angResolutionfloatProfPlot of the velocity profilemeta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlcharNEDSimbad column added by the CDSmeta.refchar_RAPositions from SIMBAD database (right ascension part)degpos.eq.ra;meta.main_DEPositions from SIMBAD database (declination part)degpos.eq.dec;meta.mainJ/AJ/146/150/table5Velocity dispersions measured in radial binsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNGCGalaxy NGC numbermeta.id;meta.mainintRgcRelative galactocentric distance (R/R_25_)pos.distance;pos.galactocentricfloatsigHI[7.5/21] The HI velocity dispersion {sigma}(HI)km/sphys.veloc.dispersion;spect.linefloatsigCO[6.7/24] The CO velocity dispersion {sigma}(CO)km/sphys.veloc.dispersion;spect.linefloatRatio[0.7/1.5] The {sigma}(HI) to {sigma}(CO) ratiophys.veloc.dispersionfloat