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dc.contributor.authorCHEN, Hao
hal.structure.identifierFORMATION STELLAIRE 2017
dc.contributor.authorBRAINE, J.
hal.structure.identifierChinese Academy of Sciences [Changchun Branch] [CAS]
dc.contributor.authorGAO, Yu
dc.contributor.authorKODA, Jin
hal.structure.identifierInstitut National des Sciences Appliquées - Rennes [INSA Rennes]
dc.contributor.authorGU, Qiusheng
dc.date.issued2017
dc.identifier.issn0004-637X
dc.description.abstractEnThere is a linear relation between the mass of dense gas, traced by the HCN(1-0) luminosity, and the star formation rate (SFR), traced by the far-infrared luminosity. Recent observations of galactic disks have shown some systematic variations. In order to explore the SFR-dense gas link at high resolution ($\sim 4"$, $\sim 150$ pc) in the outer disk of an external galaxy, we have mapped a region about 5 kpc from the center along the northern spiral arm of M51 in the HCN(1-0), HCO$^+$(1-0) and HNC(1-0) emission lines using the Northern Extended Millimeter Array (NOEMA) interferometer. The HCN and HCO$^+$ lines were detected in 6 giant molecular associations (GMAs) while HNC emission was only detected in the two brightest GMAs. One of the GMAs hosts a powerful HII region and HCN is stronger than HCO$^+$ there. Comparing with observations of GMAs in the disks of M31 and M33 at similar angular resolution ($\sim 100$ pc), we find that GMAs in the outer disk of M51 are brighter in both HCN and HCO$^+$ lines by a factor of 3 on average. However, the $I_{HCN}/I_{CO}$ and $I_{HCO^+}/I_{CO}$ ratios are similar to the ratios in nearby galactic disks and the Galactic plane. Using the Herschel 70 $\mu$m data to trace the total IR luminosity at the resolution of the GMAs, we find that both the L$_{IR}$-L$_{HCN}$ and L$_{IR}$-L$_{HCO^+}$ relations in the outer disk GMAs are consistent with the proportionality between the L$_{IR}$ and the dense gas mass established globally in galaxies within the scatter. The IR/HCN and IR/HCO$^+$ ratios of the GMAs vary by a factor of 3, probably depending on whether massive stars are forming or not.
dc.language.isoen
dc.publisherAmerican Astronomical Society
dc.subject.enAstrophysics - Astrophysics of Galaxies
dc.title.enDense Gas in the Outer Spiral Arm of M51
dc.typeArticle de revue
dc.identifier.doi10.3847/1538-4357/836/1/101
dc.subject.halPlanète et Univers [physics]/Astrophysique [astro-ph]/Astrophysique galactique [astro-ph.GA]
dc.identifier.arxiv1612.00459
bordeaux.journalThe Astrophysical Journal
bordeaux.pageid. 101
bordeaux.volume836
bordeaux.issue1
bordeaux.peerReviewedoui
hal.identifierhal-01409623
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-01409623v1
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