J/MNRAS/497/1972ivo://CDS.VizieR/J/MNRAS/497/1972doi:10.26093/cds/vizier.74971972CDSBarnes A.T.Kauffmann J.Bigiel F.Brinkmann N.Colombo D.Guzman A.E,Kim W.J.Szucs L.Wakelam V.Aalto S.Albertsson T.Evans N.J. II,Glover S.C.O.Goldsmith P.F.Kramer C.Menten K.Nishimura Y.Viti S.,Watanabe Y.Weiss A.Wienen M.Wiesemeyer H.Wyrowski F.2024-08-21T20:15:39Z2020-09-07T09:33:44ZCDS support team

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

cds-question@unistra.frstar-forming-regionsmolecular-physicsinterstellar-mediumThe current generation of (sub)mm-telescopes have allowed molecular line emission to become a major tool for studying the physical, kinematic, and chemical properties of extra-galactic systems, yet exploiting these observations requires a detailed understanding of where emission lines originate within the Milky Way. In this paper, we present 60" (~3pc) resolution observations of many 3mm-band molecular lines across a large map of the W49 massive star-forming region (~100pcx100pc at 11kpc), which were taken as part of the "LEGO" IRAM-30m large project. We find that the spatial extent or brightness of the molecular line transitions are not well correlated with their critical densities, highlighting abundance and optical depth must be considered when estimating line emission characteristics. We explore how the total emission and emission efficiency (i.e. line brightness per H_2_ column density) of the line emission vary as a function of molecular hydrogen column density and dust temperature. We find that there is not a single region of this parameter space responsible for the brightest and most efficiently emitting gas for all species. For example, we find that the HCN transition shows high emission efficiency at high column density (10^22^cm^-2^) and moderate temperatures (35K), whilst e.g. N_2_H^+^ emits most efficiently towards lower temperatures (10^22^cm^-2^; <20K). We determine X_CO(1-0)_~0.3x10^20^cm^-2^/(K.km/s), and {alpha}_HCN(1-0)_~30M_{sun}_/(K.(km/s)pc^2^), which both differ significantly from the commonly adopted values. In all, these results suggest caution in interpreting molecular line emission.2020MNRAS.497.1972Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/497/1972CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/497/1972https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/497/1972http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/497/1972https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/497/1972https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/497/1972http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/497/1972GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/MNRAS/497/1972/table2Selected observed molecular line informationrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintLEGOIdentifiermeta.id;meta.maincharMolMoleculemeta.noteTransTransitionmeta.id;phys.atmol.transitionFreqRest frequency (1)GHzem.freqdoubleEu? Upper energy level (2)Kphys.energy;phys.atmol.levelfloatnullableAij? Einstein coefficient for spontaneous emission (2)s**-1phys.atmol.transProbdoublenullableCij-2lvl? Two-level approximation for downward collisional rates coefficient (2)cm**3.s**-1arith.rate;phys.atmol.collisionaldoublenullableCij-tot? Full-level approximation for downward collisional rates coefficient (2)cm**3.s**-1arith.rate;phys.atmol.collisionaldoublenullablencrit-2lvl? Two-level approximation for critical density for emissioncm**-3phys.densitydoublenullablencrit-tot? Full-level approximation for critical density for emissioncm**-3phys.densitydoublenullableeffncritEffective density for emissioncm**-3phys.densityintJ/MNRAS/497/1972/table3b1Molecular line cube and integrated intensity map statistics (Table 3 and B1)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintLEGOIdentifiermeta.id;meta.maincharrmsAverage rms within the cubes within a 1km/s channelKstat.stdevdoublesigmaMean uncertainty of the integrated intensityK.km/sstat.error;phot.flux.density;stat.meandoublecoverageArea percentage containing significant emission%phys.angSizedoublemin-nsMinimum integrated intensity of all pixels within the mapK.km/sphot.flux.density;stat.mindoubleminMinimum integrated intensity of significant pixels within the mapK.km/sphot.flux.density;stat.mindoublep55 percentile integrated intensity of significant pixels within the mapK.km/sphot.flux.density;obs.fielddoublep1616 percentile integrated intensity of significant pixels within the mapK.km/sphot.flux.density;obs.fielddoublemeanMean integrated intensity of significant pixels within the mapK.km/sphot.flux.density;stat.meandoublemedianMedian integrated intensity of significant pixels within the mapK.km/sphot.flux.density;stat.mediandoublep8484 percentile integrated intensity of significant pixels within the mapK.km/sphot.flux.density;obs.fielddoublep9595 percentile integrated intensity of significant pixels within the mapK.km/sphot.flux.density;obs.fielddoublemaximumMaximum integrated intensity of significant pixels within the mapK.km/sphot.flux.density;stat.maxdoubleJ/MNRAS/497/1972/table4Characteristic column and number densities of molecular hydrogenrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintLEGOIdentifiermeta.id;meta.maincharNchar-allCharacteristic column density across the whole mapcm**-2phys.columnDensity;obs.fielddoublee_Nchar-allError on the characteristic column density across the whole mapcm**-2stat.errordoubleNchar-w49aCharacteristic column density across W49A onlycm**-2phys.columnDensitydoublee_Nchar-w49aError on the characteristic column density across W49A onlycm**-2stat.errordoublenchar-w49aCharacteristic number density across W49A onlycm**-3meta.iddoublee_nchar-w49aError on the characteristic number density across W49A onlycm**-3stat.errordoubleJ/MNRAS/497/1972/tablea1Molecular line information for the LEGO survey pipelinerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintLEGOIdentifiermeta.id;meta.maincharMolMoleculemeta.noteTransTransitionmeta.id;phys.atmol.transitionFreq[86.3/115.3]? Rest frequency (Lovas/NIST database; Lovas 2004JPCRD..33..177L)GHzem.freqdoublenullableFreqMin[86.3/113.5]? Minimum group frequencyGHzem.freq;stat.mindoublenullableFreqMax[86.3/113.6]? Maximum group frequencyGHzem.freq;stat.maxdoublenullableCommComments on groupmeta.note;pos.lgcharJ/MNRAS/497/1972/tablee1aMolecular hydrogen column density and mass conversion factors calculated using the column density and mass of Av>8mag gas divided by the mean integrated intensity and total luminosity of the given line across the region (top half of Table E1)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintLEGOIdentifiermeta.id;meta.maincharlogW? Mean integrated intensity (log10)log(K.km.s**-1)phot.flux.density;stat.meandoublenullablee_logW[] Error on integrated intensity (log10)log(K.km.s**-1)stat.error;pos.cartesian.zdoublelogL? Sum luminosity (log10)log(K.km.s**-1.pc**2)phys.luminositydoublenullablee_logL[] Error on sum luminosity (log10)log(K.km.s**-1.pc**2)stat.errordoubleXQColumn density conversion factor (Xfactor)cm**-2.K**-1.km**-1.sarith.factordoublee_XQ[] Error on column density conversion factor (X-factor)cm**-2.K**-1.km**-1.sstat.errordoubleaQMass conversion factor (alpha-factor)solMass.K**-1.km**-1.s.pc**-2arith.factor;phys.massdoublee_aQ[] Error on mass conversion factor (alpha-factor)solMass.K**-1.km**-1.s.pc**-2stat.errordoubleJ/MNRAS/497/1972/tablee1bMolecular hydrogen column density and mass conversion factors calculated using both the column density and mass, and integrated intensity and luminosity above the Av>8mag threshold (bottom half of Table E1)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintLEGOIdentifiermeta.id;meta.maincharlogW? Mean integrated intensity (log10)log(K.km.s**-1)phot.flux.density;stat.meandoublenullablee_logW[] Error on integrated intensity (log10)log(K.km.s**-1)stat.error;pos.cartesian.zdoublelogL? Sum luminosity (log10)log(K.km.s**-1.pc**2)phys.luminositydoublenullablee_logL[] Error on sum luminosity (log10)log(K.km.s**-1.pc**2)stat.errordoubleXQColumn density conversion factor (Xfactor)cm**-2.K**-1.km**-1.sarith.factordoublee_XQ[] Error on column density conversion factor (X-factor)cm**-2.K**-1.km**-1.sstat.errordoubleaQMass conversion factor (alpha-factor)solMass.K**-1.km**-1.s.pc**-2arith.factor;phys.massdoublee_aQ[] Error on mass conversion factor (alpha-factor)solMass.K**-1.km**-1.s.pc**-2stat.errordoubleJ/MNRAS/497/1972/tablee2Molecular hydrogen column density and mass conversion factors calculated without imposing any extinction threshold on the gas column density and gas mass, and the integrated intensity and luminosity of the given linerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintLEGOIdentifiermeta.id;meta.maincharlogW? Mean integrated intensity (log10)log(K.km.s**-1)phot.flux.density;stat.meandoublenullablee_logW[] Error on integrated intensity (log10)log(K.km.s**-1)stat.error;pos.cartesian.zdoublelogL? Sum luminosity (log10)log(K.km.s**-1.pc**2)phys.luminositydoublenullablee_logL[] Error on sum luminosity (log10)log(K.km.s**-1.pc**2)stat.errordoubleXQColumn density conversion factor (Xfactor)cm**-2.K**-1.km**-1.sarith.factordoublee_XQ[] Error on column density conversion factor (X-factor)cm**-2.K**-1.km**-1.sstat.errordoubleaQMass conversion factor (alpha-factor)solMass.K**-1.km**-1.s.pc**-2arith.factor;phys.massdoublee_aQ[] Error on mass conversion factor (alpha-factor)solMass.K**-1.km**-1.s.pc**-2stat.errordouble