Origin of Warm High-Velocity Dense Gas in Ultraluminous Infrared Galaxies

[摘要] Possibleoriginsofmolecularabsorptiondiscoveredinsomeultraluminousinfraredgalaxies(ULIRGs)areinvestigated,basedona3-Dhydrodynamicmodelofstar-forminginterstellargasinagalacticcentralregion.Theblueshifted,warm($$sim$$200–300K),dense($$gt10^6$$cm$$^{-3}$$)moleculargassuggestedbytheCOabsorptioninIRAS08572$$+$$3915couldbecausedbytheinnermostregionoftheinhomogeneousinterstellarmedium(ISM)aroundasupermassiveblackhole.TheinfrequentobservationsofdensegaswithabsorptioninULIRGsandtype-2Seyfertgalaxiescouldsimplysuggestthatthehigh-densityregionsoccupyonlyaverysmallvolumefractionoftheobscuringmaterial.ThisisnaturallyexpectediftheinhomogeneousstructureoftheISMiscausedbyanonlineardevelopmentofinstabilities.Sincethemodelpredictsaturbulentvelocityfieldintheobscuringmaterial,blue-andred-shiftedgasesshouldbeobservablewithnearlythesameprobabilityforsufficientlylargestatisticalsamples.

[学科分类] 天文学(综合)

[关键词] "galaxies: Seyfert";"galaxies: starburst";"ISM: kinematics and dynamics"