J/ApJ/858/90ivo://CDS.VizieR/J/ApJ/858/90doi:10.26093/cds/vizier.18580090CDSGallagher M.J.Leroy A.K.Bigiel F.Cormier D.Jimenez-Donaire M.J.,Ostriker E.Usero A.Bolatto A.D.Garcia-Burillo S.Hughes A.,Kepley A.A.Krumholz M.Meidt S.E.Meier D.S.Murphy E.J.Pety J.,Rosolowsky E.Schinnerer E.Schruba A.Walter F.2019-05-10T11:46:44Z2019-05-06T11:55:09ZCDS support team

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

cds-question@unistra.frgalaxiesinterferometryradio-astronomyinfrared-sourcesinterstellar-mediumWe use new ALMA observations to investigate the connection between dense gas fraction, star formation rate (SFR), and local environment across the inner region of four local galaxies showing a wide range of molecular gas depletion times. We map HCN(1-0), HCO^+^(1-0), CS(2-1), ^13^CO(1-0), and C^18^O(1-0) across the inner few kiloparsecs of each target. We combine these data with short-spacing information from the IRAM large program EMPIRE, archival CO maps, tracers of stellar structure and recent star formation, and recent HCN surveys by Bigiel+ (2016ApJ...822L..26B) and Usero+ (2015AJ....150..115U). We test the degree to which changes in the dense gas fraction drive changes in the SFR. I_HCN_/I_CO_ (tracing the dense gas fraction) correlates strongly with I_CO_ (tracing molecular gas surface density), stellar surface density, and dynamical equilibrium pressure, P_DE_ (Elmegreen 1989ApJ...338..178E). Therefore, I_HCN_/I_CO_ becomes very low and HCN becomes very faint at large galactocentric radii, where ratios as low as I_HCN_/I_CO_~0.01 become common. The apparent ability of dense gas to form stars, {Sigma}_SFR_/{Sigma}_dense_ (where {Sigma}_dense_ is traced by the HCN intensity and the star formation rate is traced by a combination of H{alpha} and 24{mu}m emission), also depends on environment. {Sigma}_SFR_/{Sigma}_dense_ decreases in regions of high gas surface density, high stellar surface density, and high P_DE_. Statistically, these correlations between environment and both {Sigma}_SFR_/{Sigma}_dense_ and I_HCN_/I_CO_ are stronger than that between apparent dense gas fraction (I_HCN_/I_CO_) and the apparent molecular gas star formation efficiency {Sigma}_SFR_/{Sigma}_mol_. We show that these results are not specific to HCN.2018ApJ...858...90Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/858/90CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/iram : IRAM Observation Logs (IRAM 1991-2015)VI/139 : Herschel Observation Log (Herschel Science Centre, 2013)J/ApJ/671/333 : Aperture photometry in NGC 5194 (Kennicutt+, 2007)J/AJ/136/2782 : Star formation efficiency in nearby galaxies (Leroy+, 2008)J/AJ/136/2563 : HI Nearby Galaxy Survey, THINGS (Walter+, 2008)J/ApJS/184/1 : Molecular clouds in the LMC by NANTEN. II. (Kawamura+, 2009)J/ApJ/706/599 : H{alpha} and UV SFR in the local volume (Lee+, 2009)J/ApJ/701/1965 : Radial dust properties of SINGS galaxies (Munoz-Mateos+, 2009)J/ApJ/714/1256 : Far-IR star formation rate indicators (Calzetti+, 2010)J/ApJ/723/1019 : Galactic SFR and gas surface densities (Heiderman+, 2010)J/PASP/122/1397 : Spitzer Survey of Stellar Structure in Gal. (Sheth+, 2010)J/AJ/146/150 : Veloc. dispersions of 12 nearby galaxies (Caldu-Primo+, 2013)J/ApJ/771/59 : Surface brightness of S^4^G face-on gal. (Munoz-Mateos+, 2013)J/A+A/584/A91 : Cat. of dense cores in Aquila from Herschel (Konyves+, 2015)J/ApJ/846/159 : Interferometric CO obs. of 126 CALIFA gal. (Bolatto+, 2017)J/ApJ/846/71 : M51 ISM structures from the CO maps of PAWS (Leroy+, 2017)J/ApJ/835/217 : Density distributions for mm-wave line ratios (Leroy+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/858/90https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/858/90http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/858/90https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/858/90https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/858/90http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/858/90GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/858/90/table2 (Targets observed)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/858/90/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/858/90/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/858/90/table2?GETtext/xml+votable180.050000true160.99041711.7038060.0055555555555555566/11027 27514 27861 28035 28167https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/858/90?format=asciiInfraredRadiodefaultJ/ApJ/858/90/table2Targets observedNGCNGC number of the galaxymeta.id;meta.mainintprimaryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintn_NGC30m: Observed with the IRAM 30m (1)meta.notecharRAJ2000[160.9/202.5] Right ascension (J2000) (2)degpos.eq.ra;meta.mainDEJ2000[11.7/47.2] Declination (J2000) (2)degpos.eq.dec;meta.mainMorphMorphology from NEDsrc.morphcharInc[22/62] Inclination (3)degsrc.orbital.inclinationfloatPA[7.5/192] Position angle, north through eastdegpos.posAngfloatr_PASource for orientation parameters (4)meta.ref;pos.framecharDist[7.6/14.4] Adopted distance of the galaxy from Kennicutt+ (2011PASP..123.1347K)Mpcpos.distance;pos.heliocentricfloatBeam[295/636] Linear beam (5)pcpos.distance;phys.size;instr.beamintFOVField of view across the dense gas maps at the distance of the galaxy without accounting for inclinationkpcpos.distance;instr.fovcharNmNumber of measurements (link to suppmat)meta.numberintnullablePlotIntensity profile plotmeta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlcharNEDNED column added by the CDSmeta.ref.urlcharLEDAmeta.ref.urlcharJ/ApJ/858/90/suppmatRadial profile data table (Appendix C)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNGCNGC number of the galaxymeta.id;meta.mainintRad[0.03/6] Inner radius of ringkpcphys.size.radiusfloatI-CO[0/139] Average intensity, CO 1-0K.km/sphot.flux.density;em.line.CO;stat.meanfloate_I-CO[0/2.1]? Uncertainty, rms, in I-COK.km/sstat.errorfloatnullableI-HCN[-0.008/9.6] Average intensity, HCN 1-0K.km/sphot.flux.density;em.radio;stat.meanfloate_I-HCN[0/0.2]? Uncertainty, rms, in I-HCNK.km/sstat.error;phot.color;em.opt.IfloatnullableI-CS[-0.07/3]? Average intensity, CS 2-1K.km/sphot.flux.density;em.radio;stat.meandoublenullablee_I-CS[0/0.2]? Uncertainty, rms, in I-CSK.km/sstat.errordoublenullableI-HCO+[-0.03/6.1] Average intensity, HCO^+^ 1-0K.km/sphot.flux.density;em.radio;stat.meanfloate_I-HCO+[0/0.2]? Uncertainty, rms, in I-HCO+K.km/sstat.error;phot.color;em.opt.IfloatnullableI-13CO[0/12] Average intensity, 13CO 1-0K.km/sphot.flux.density;em.line.CO;stat.meanfloate_I-13CO[0/0.2]? Uncertainty, rms, in ^13^COK.km/sstat.errorfloatnullableI-C18O[-0.08/2.2]? Average intensity, C^18^O 1-0K.km/sphot.flux.density;em.radio;stat.meandoublenullablee_I-C18O[0/0.2]? Uncertainty, rms, in I-C18OK.km/sstat.errordoublenullableI-3.6um[0.2/14.4] Average intensity, 3.6umMJy/srspect.line.intensity;em.IR.3-4um;stat.meandoublee_I-3.6um[0.0001/0.005] Uncertainty, rms, in I-3.6umMJy/srstat.errordoubleI-24um[0.1/227] Average intensity, 24umMJy/srspect.line.intensity;em.IR.15-30um;stat.meandoublee_I-24um[0.0009/0.03] Uncertainty, rms, in I-24umMJy/srstat.errorfloatI-70um[2.9/2571] Average intensity, 70umMJy/srspect.line.intensity;em.IR.60-100um;stat.meanfloate_I-70um[0.02/1] Uncertainty, rms, in I-70umMJy/srstat.errorfloatI-FUV[0.001/0.5] Average intensity, FUVMJy/srspect.line.intensity;em.UV.100-200nm;stat.meandoublee_I-FUV[/0.0003] Uncertainty, rms, in I-FUVMJy/srstat.errordoubleI-Ha[1.7e-06/8.5e-05] Average intensity, H{alpha}, erg/s/cm2/sr (1)mW.m**-2.sr**-1spect.line.intensity;em.line.Halpha;stat.meandoublee_I-HaUncertainty, rms, in I-HamW.m**-2.sr**-1stat.error;phot.color;em.opt.IdoublePDE[2942/1.9e+07] Dynamical equilibrium pressurecm**-3.K**-1phys.pressuredoublee_PDE[345/1.5e+06]? Uncertainty, rms, in PDEcm**-3.K**-1stat.errordoublenullableSd*[78.8/5043] Stellar surface denistysolMass.pc**-2phot.sbfloate_Sd*[0/37] Uncertainty, rms, in Sd*solMass.pc**-2stat.errorfloatTIR70[5.2e+33/1.7e+36] Total infrared average intensity from 70umW.kpc**-2em.IR;stat.meandoublee_TIR70[8.6e+32/2.2e+33] Uncertainty, rms, in TIR70W.kpc**-2stat.errordoubleTIR24[2e+33/1.4e+36] Total infrared average intensity from 24umW.kpc**-2em.IR;stat.meandoublee_TIR24[6.5e+33/2.3e+34] Uncertainty, rms, in TIR24W.kpc**-2stat.errordoubleSd-gas[0.6/602]? Total (HI+molecular) gas surface densitysolMass.pc**-2phot.flux.density.sbfloatnullablee_Sd-gas[0.1/53]? Uncertainty, rms, in Sd-gassolMass.pc**-2stat.errorfloatnullableSd-mol[0/595] Molecular gas surface densitysolMass.pc**-2phot.flux.density.sbfloate_Sd-mol[0/9] Uncertainty, rms, in Sd-molsolMass.pc**-2stat.errorfloatSd-dense[-0.08/96] Dense gas surface densitysolMass.pc**-2phot.flux.density.sbfloate_Sd-dense[0/1.1] Uncertainty, rms, in Sd-densesolMass.pc**-2stat.errorfloatSFR-TIR70um[2e-09/6.6e-07] Star formation rate TIR_70solMass.pc**-2.yr**-1phys.SFRdoublee_SFR-TIR70umUncertainty, rms, in SFR-70umsolMass.pc**-2.yr**-1stat.errordoubleSFR-TIR24um[8.3e-10/5.5e-07] Star formation rate TIR_24solMass.pc**-2.yr**-1phys.SFRdoublee_SFR-TIR24um[2.5e-09/9e-09] Uncertainty, rms, in SFR-24umsolMass.pc**-2.yr**-1stat.errordoubleSFR-Ha+24um[1.4e-09/6e-07] Star formation rate Halpha+24umsolMass.pc**-2.yr**-1phys.SFR;spect.linedoublee_SFR-Ha+24um[1e-11/2e-09] Uncertainty, rms, in SFR-Ha+24umsolMass.pc**-2.yr**-1stat.errordoubleSFR-FUV+24um[5.6e-10/7.6e-07] Star formation rate FUV+24umsolMass.pc**-2.yr**-1phys.SFRdoublee_SFR-FUV+24umUncertainty, rms, in SFR-FUV+24umsolMass.pc**-2.yr**-1stat.errordoubleSd-HI[0.01/2.4e+19] HI gas surface densitysolMass.pc**-2phot.flux.density.sb;em.line.HIdoublee_Sd-HIUncertainty, rms, in Sd-HIsolMass.pc**-2stat.errordoubleSFR-24um[4.3e-10/7.3e-07] Star formation rate 24um onlysolMass.pc**-2.yr**-1phys.SFRdoublee_SFR-24umUncertainty, rms, in SFR-24umsolMass.pc**-2.yr**-1stat.errordoubleSFR-FUV[9.8e-11/3.5e-08] Star formation rate FUV onlysolMass.pc**-2.yr**-1phys.SFRdoublee_SFR-FUVUncertainty, rms, in SFR-FUVsolMass.pc**-2.yr**-1stat.errordoubleSFR-Ha[1e-09/5.4e-08] Star formation rate Halpha onlysolMass.pc**-2.yr**-1phys.SFR;spect.linedoublee_SFR-HaUncertainty, rms, in SFR-HasolMass.pc**-2.yr**-1stat.errordouble