It is still poorly constrained how the densest phase of the interstellar medium varies across galactic environment. A large observing time is required to recover significant emission from dense molecular gas at high spatial resolution, and to cover a large dynamic range of extragalactic disc environments. We present new NOrthern Extended Millimeter Array (NOEMA) observations of a range of high critical density molecular tracers (HCN, HNC, HCO+) and CO isotopologues ((CO)-C-13, (CO)-O-18) towards the nearby (11.3 Mpc) strongly barred galaxy NGC 3627. These observations represent the current highest angular resolution (1.85 arcsec; 100 pc) map of dense gas tracers across a disc of a nearby spiral galaxy, which we use here to assess the properties of the dense molecular gas, and their variation as a function of galactocentric radius, molecular gas, and star formation. We find that the HCN(1-0)/CO(2-1) integrated intensity ratio does not correlate with the amount of recent star formation. Instead, the HCN(1-0)/CO(2-1) ratio depends on the galactic environment, with differences between the galaxy centre, bar, and bar-end regions. The dense gas in the central 600 pc appears to produce stars less efficiently despite containing a higher fraction of dense molecular gas than the bar ends where the star formation is enhanced. In assessing the dynamics of the dense gas, we find the HCN(1-0) and HCO+(1-0) emission lines showing multiple components towards regions in the bar ends that correspond to previously identified features in CO emission. These features are cospatial with peaks of H alpha emission, which highlights that the complex dynamics of this bar-end region could be linked to local enhancements in the star formation.

Dense molecular gas properties on 100 pc scales across the disc of NGC 3627

Sormani M;
2021-01-01

Abstract

It is still poorly constrained how the densest phase of the interstellar medium varies across galactic environment. A large observing time is required to recover significant emission from dense molecular gas at high spatial resolution, and to cover a large dynamic range of extragalactic disc environments. We present new NOrthern Extended Millimeter Array (NOEMA) observations of a range of high critical density molecular tracers (HCN, HNC, HCO+) and CO isotopologues ((CO)-C-13, (CO)-O-18) towards the nearby (11.3 Mpc) strongly barred galaxy NGC 3627. These observations represent the current highest angular resolution (1.85 arcsec; 100 pc) map of dense gas tracers across a disc of a nearby spiral galaxy, which we use here to assess the properties of the dense molecular gas, and their variation as a function of galactocentric radius, molecular gas, and star formation. We find that the HCN(1-0)/CO(2-1) integrated intensity ratio does not correlate with the amount of recent star formation. Instead, the HCN(1-0)/CO(2-1) ratio depends on the galactic environment, with differences between the galaxy centre, bar, and bar-end regions. The dense gas in the central 600 pc appears to produce stars less efficiently despite containing a higher fraction of dense molecular gas than the bar ends where the star formation is enhanced. In assessing the dynamics of the dense gas, we find the HCN(1-0) and HCO+(1-0) emission lines showing multiple components towards regions in the bar ends that correspond to previously identified features in CO emission. These features are cospatial with peaks of H alpha emission, which highlights that the complex dynamics of this bar-end region could be linked to local enhancements in the star formation.
2021
2021
stars: formation, ISM: clouds, ISM: molecules, galaxies: evolution, galaxies: ISM, galaxies: star formation
Beslic, I; Barnes, At; Bigiel, F; Puschnig, J; Pety, J; Contreras, Ch; Leroy, Ak; Usero, A; Schinnerer, E; Meidt, Se; Emsellem, E; Hughes, A; Faesi, C; Kreckel, K; Belfiore, Fmc; Chevance, M; den Brok, Js; Eibensteiner, C; Glover, Sco; Grasha, K; Jimenez-Donaire, Mj; Klessen, Rs; Kruijssen, Jmd; Liu, D; Pessa, I; Querejeta, M; Rosolowsky, E; Saito, T; Santoro, F; Schruba, A; Sormani, M; Williams, Tg
File in questo prodotto:
File Dimensione Formato  
Beslic2021.pdf

non disponibili

Tipologia: Versione Editoriale (PDF)
Licenza: Copyright dell'editore
Dimensione 6.81 MB
Formato Adobe PDF
6.81 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11383/2171040
 Attenzione

L'Ateneo sottopone a validazione solo i file PDF allegati

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 20
  • ???jsp.display-item.citation.isi??? 19
social impact