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Dense Gas, Dynamical Equilibrium Pressure, and Star Formation in Nearby Star-forming Galaxies

Gallagher, Molly; Leroy, Adam K.; Bigiel, Frank; Cormier, Diane; Jimenez-Donaire, Maria J.; Ostriker, Eve C.; Usero, Antonio; Bolatto, Alberto; García-Burillo, Santiago; Hughes, Annie; Kepley, Amanda A.; Krumholz, Mark; Meidt, Sharon E.; Meier, David; Murphy, Eric; Pety, Jerome; Rosolowsky, Erik; Schinnerer, Eva; Schruba, Andreas; Walter, Fabian; Hughes, A.

Description

We 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), 13CO (1–0), and C18O (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...[Show more]

dc.contributor.authorGallagher, Molly
dc.contributor.authorLeroy, Adam K.
dc.contributor.authorBigiel, Frank
dc.contributor.authorCormier, Diane
dc.contributor.authorJimenez-Donaire, Maria J.
dc.contributor.authorOstriker, Eve C.
dc.contributor.authorUsero, Antonio
dc.contributor.authorBolatto, Alberto
dc.contributor.authorGarcía-Burillo, Santiago
dc.contributor.authorHughes, Annie
dc.contributor.authorKepley, Amanda A.
dc.contributor.authorKrumholz, Mark
dc.contributor.authorMeidt, Sharon E.
dc.contributor.authorMeier, David
dc.contributor.authorMurphy, Eric
dc.contributor.authorPety, Jerome
dc.contributor.authorRosolowsky, Erik
dc.contributor.authorSchinnerer, Eva
dc.contributor.authorSchruba, Andreas
dc.contributor.authorWalter, Fabian
dc.contributor.authorHughes, A.
dc.date.accessioned2019-12-06T01:16:44Z
dc.date.available2019-12-06T01:16:44Z
dc.identifier.issn0004-637X
dc.identifier.urihttp://hdl.handle.net/1885/188459
dc.description.abstractWe 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), 13CO (1–0), and C18O (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 et al. and Usero et al. We test the degree to which changes in the dense gas fraction drive changes in the SFR. ${I}_{\mathrm{HCN}}/{I}_{\mathrm{CO}}$ (tracing the dense gas fraction) correlates strongly with I CO (tracing molecular gas surface density), stellar surface density, and dynamical equilibrium pressure, P DE. Therefore, ${I}_{\mathrm{HCN}}/{I}_{\mathrm{CO}}$ becomes very low and HCN becomes very faint at large galactocentric radii, where ratios as low as ${I}_{\mathrm{HCN}}/{I}_{\mathrm{CO}}\sim 0.01$ become common. The apparent ability of dense gas to form stars, ${{\rm{\Sigma }}}_{\mathrm{SFR}}/{{\rm{\Sigma }}}_{\mathrm{dense}}$ (where Σdense is traced by the HCN intensity and the star formation rate is traced by a combination of Hα and 24 μm emission), also depends on environment. ${{\rm{\Sigma }}}_{\mathrm{SFR}}/{{\rm{\Sigma }}}_{\mathrm{dense}}$ decreases in regions of high gas surface density, high stellar surface density, and high P DE. Statistically, these correlations between environment and both ${{\rm{\Sigma }}}_{\mathrm{SFR}}/{{\rm{\Sigma }}}_{\mathrm{dense}}$ and ${I}_{\mathrm{HCN}}/{I}_{\mathrm{CO}}$ are stronger than that between apparent dense gas fraction (${I}_{\mathrm{HCN}}/{I}_{\mathrm{CO}}$) and the apparent molecular gas star formation efficiency ${{\rm{\Sigma }}}_{\mathrm{SFR}}/{{\rm{\Sigma }}}_{\mathrm{mol}}$. We show that these results are not specific to HCN.
dc.format.mimetypeapplication/pdf
dc.language.isoen_AU
dc.publisherIOP Publishing
dc.rights© 2018 The American Astronomical Society
dc.sourceThe Astrophysical Journal
dc.subjectgalaxies: ISM
dc.subjectgalaxies: star formation
dc.subjectradio lines: ISM
dc.titleDense Gas, Dynamical Equilibrium Pressure, and Star Formation in Nearby Star-forming Galaxies
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume858
dc.date.issued2018-05-10
local.identifier.absfor020103 - Cosmology and Extragalactic Astronomy
local.identifier.ariespublicationa383154xPUB10068
local.publisher.urlhttps://iopscience.iop.org
local.type.statusPublished Version
local.contributor.affiliationGallagher, Molly, The Ohio State University
local.contributor.affiliationLeroy, Adam K., The Ohio State University
local.contributor.affiliationBigiel, Frank, Zentrum für Astronomie der Universität Heidelberg
local.contributor.affiliationCormier, Diane, Zentrum für Astronomie der Universität Heidelberg
local.contributor.affiliationJimenez-Donaire, Maria J., Zentrum für Astronomie der Universität Heidelberg
local.contributor.affiliationOstriker, Eve C., Princeton University
local.contributor.affiliationUsero, Antonio, Observatorio Astronómico Naciona
local.contributor.affiliationBolatto, Alberto, University of Maryland
local.contributor.affiliationGarcía-Burillo, Santiago, Observatorio Astronomico Nacional
local.contributor.affiliationHughes, Annie, CNRS
local.contributor.affiliationKepley, Amanda A., National Radio Astronomy Observatory
local.contributor.affiliationKrumholz, Mark, College of Science, ANU
local.contributor.affiliationMeidt, Sharon E., Max Planck Institut fur Astronomie
local.contributor.affiliationMeier, David, New Mexico Institute of Mining and Technology
local.contributor.affiliationMurphy, Eric, National Radio Astronomy Observatory
local.contributor.affiliationPety, Jerome, Observatoire de Paris
local.contributor.affiliationRosolowsky, Erik, Department of Physics, 4-181 CCIS, University of Alberta
local.contributor.affiliationSchinnerer, Eva, Max Planck Institut fur Astronomie
local.contributor.affiliationSchruba, Andreas, Max-Planck-Institut für extraterrestrische Physik
local.contributor.affiliationWalter, Fabian, Max Planck Institute for Astronomy
local.contributor.affiliationHughes, A., Université de Toulouse
local.bibliographicCitation.issue2
local.bibliographicCitation.startpage1
local.bibliographicCitation.lastpage29
local.identifier.doi10.3847/1538-4357/aabad8
local.identifier.absseo970102 - Expanding Knowledge in the Physical Sciences
dc.date.updated2019-07-28T08:16:46Z
local.identifier.scopusID2-s2.0-85047213012
dcterms.accessRightsOpen Access
dc.provenancehttp://sherpa.ac.uk/romeo/issn/0004-637X/..."author can archive publisher's version/PDF" from SHERPA/RoMEO site (as at 6/12/19)
CollectionsANU Research Publications

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