A 2-3 mm high-resolution molecular line survey towards the centre of the nearby spiral galaxy NGC 6946

C. Eibensteiner; A. T. Barnes; F. Bigiel; E. Schinnerer; D. Liu; D. S. Meier; A. Usero; A. K. Leroy; E. Rosolowsky; J. Puschnig; I. Lazar; J. Pety; L. A. Lopez; E. Emsellem; I. Bešlić; M. Querejeta; E. J. Murphy; J. Den Brok; A. Schruba; M. Chevance; S. C.O. Glover; Y. Gao; K. Grasha; H. Hassani; J. D. Henshaw; M. J. Jimenez-Donaire; R. S. Klessen; J. M.D. Kruijssen; H. A. Pan; T. Saito; M. C. Sormani; Y. H. Teng; T. G. Williams

doi:10.1051/0004-6361/202142624

A 2-3 mm high-resolution molecular line survey towards the centre of the nearby spiral galaxy NGC 6946

C. Eibensteiner^*, A. T. Barnes, F. Bigiel, E. Schinnerer, D. Liu, D. S. Meier, A. Usero, A. K. Leroy, E. Rosolowsky, J. Puschnig, I. Lazar, J. Pety, L. A. Lopez, E. Emsellem, I. Bešlić, M. Querejeta, E. J. Murphy, J. Den Brok, A. Schruba, M. ChevanceS. C.O. Glover, Y. Gao, K. Grasha, H. Hassani, J. D. Henshaw, M. J. Jimenez-Donaire, R. S. Klessen, J. M.D. Kruijssen, H. A. Pan, T. Saito, M. C. Sormani, Y. H. Teng, T. G. Williams

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

18 Citations (Scopus)

Abstract

The complex physical, kinematic, and chemical properties of galaxy centres make them interesting environments to examine with molecular line emission. We present new 2-4″ (∼75-150 pc at 7.7 Mpc) observations at 2 and 3mm covering the central 50″ (∼1:9 kpc) of the nearby doublebarred spiral galaxy NGC6946 obtained with the IRAM Plateau de Bure Interferometer. We detect spectral lines from ten molecules: CO, HCN, HCO+, HNC, CS, HC3N, N2H+, C2H, CH3OH, and H2CO. We complemented these with published 1mm CO observations and 33 GHz continuum observations to explore the star formation rate surface density ΣSFR on 150 pc scales. In this paper, we analyse regions associated with the inner bar of NGC6946 - the nuclear region (NUC), the northern (NBE), and southern inner bar end (SBE) and we focus on short-spacing corrected bulk (CO) and dense gas tracers (HCN, HCO+, and HNC). We find that HCO+ correlates best with ΣSFR, but the dense gas fraction (fdense) and star formation efficiency of the dense gas (SFEdense) fits show different behaviours than expected from large-scale disc observations. The SBE has a higher ΣSFR, fdense, and shocked gas fraction than the NBE. We examine line ratio diagnostics and find a higher CO(2-1)/CO(1-0) ratio towards NBE than for the NUC. Moreover, comparison with existing extragalactic datasets suggests that using the HCN/HNC ratio to probe kinetic temperatures is not suitable on kiloparsec and sub-kiloparsec scales in extragalactic regions. Lastly, our study shows that the HCO+=HCN ratio might not be a unique indicator to diagnose AGN activity in galaxies.

Original language	English
Article number	A173
Journal	Astronomy and Astrophysics
Volume	659
DOIs	https://doi.org/10.1051/0004-6361/202142624
Publication status	Published - 1 Mar 2022

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Eibensteiner, C., Barnes, A. T., Bigiel, F., Schinnerer, E., Liu, D., Meier, D. S., Usero, A., Leroy, A. K., Rosolowsky, E., Puschnig, J., Lazar, I., Pety, J., Lopez, L. A., Emsellem, E., Bešlić, I., Querejeta, M., Murphy, E. J., Den Brok, J., Schruba, A., ... Williams, T. G. (2022). A 2-3 mm high-resolution molecular line survey towards the centre of the nearby spiral galaxy NGC 6946. Astronomy and Astrophysics, 659, Article A173. https://doi.org/10.1051/0004-6361/202142624

@article{6a54606f8b974ffa8ac19c7242b2135e,

title = "A 2-3 mm high-resolution molecular line survey towards the centre of the nearby spiral galaxy NGC 6946",

abstract = "The complex physical, kinematic, and chemical properties of galaxy centres make them interesting environments to examine with molecular line emission. We present new 2-4″ (∼75-150 pc at 7.7 Mpc) observations at 2 and 3mm covering the central 50″ (∼1:9 kpc) of the nearby doublebarred spiral galaxy NGC6946 obtained with the IRAM Plateau de Bure Interferometer. We detect spectral lines from ten molecules: CO, HCN, HCO+, HNC, CS, HC3N, N2H+, C2H, CH3OH, and H2CO. We complemented these with published 1mm CO observations and 33 GHz continuum observations to explore the star formation rate surface density ΣSFR on 150 pc scales. In this paper, we analyse regions associated with the inner bar of NGC6946 - the nuclear region (NUC), the northern (NBE), and southern inner bar end (SBE) and we focus on short-spacing corrected bulk (CO) and dense gas tracers (HCN, HCO+, and HNC). We find that HCO+ correlates best with ΣSFR, but the dense gas fraction (fdense) and star formation efficiency of the dense gas (SFEdense) fits show different behaviours than expected from large-scale disc observations. The SBE has a higher ΣSFR, fdense, and shocked gas fraction than the NBE. We examine line ratio diagnostics and find a higher CO(2-1)/CO(1-0) ratio towards NBE than for the NUC. Moreover, comparison with existing extragalactic datasets suggests that using the HCN/HNC ratio to probe kinetic temperatures is not suitable on kiloparsec and sub-kiloparsec scales in extragalactic regions. Lastly, our study shows that the HCO+=HCN ratio might not be a unique indicator to diagnose AGN activity in galaxies.",

keywords = "Galaxies: ISM, Galaxies: individual: NGC 6946, ISM: molecules",

author = "C. Eibensteiner and Barnes, {A. T.} and F. Bigiel and E. Schinnerer and D. Liu and Meier, {D. S.} and A. Usero and Leroy, {A. K.} and E. Rosolowsky and J. Puschnig and I. Lazar and J. Pety and Lopez, {L. A.} and E. Emsellem and I. Be{\v s}li{\'c} and M. Querejeta and Murphy, {E. J.} and {Den Brok}, J. and A. Schruba and M. Chevance and Glover, {S. C.O.} and Y. Gao and K. Grasha and H. Hassani and Henshaw, {J. D.} and Jimenez-Donaire, {M. J.} and Klessen, {R. S.} and Kruijssen, {J. M.D.} and Pan, {H. A.} and T. Saito and Sormani, {M. C.} and Teng, {Y. H.} and Williams, {T. G.}",

note = "Publisher Copyright: {\textcopyright} 2022 ESO.",

year = "2022",

month = mar,

day = "1",

doi = "10.1051/0004-6361/202142624",

language = "English",

volume = "659",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

Eibensteiner, C, Barnes, AT, Bigiel, F, Schinnerer, E, Liu, D, Meier, DS, Usero, A, Leroy, AK, Rosolowsky, E, Puschnig, J, Lazar, I, Pety, J, Lopez, LA, Emsellem, E, Bešlić, I, Querejeta, M, Murphy, EJ, Den Brok, J, Schruba, A, Chevance, M, Glover, SCO, Gao, Y, Grasha, K, Hassani, H, Henshaw, JD, Jimenez-Donaire, MJ, Klessen, RS, Kruijssen, JMD, Pan, HA, Saito, T, Sormani, MC, Teng, YH & Williams, TG 2022, 'A 2-3 mm high-resolution molecular line survey towards the centre of the nearby spiral galaxy NGC 6946', Astronomy and Astrophysics, vol. 659, A173. https://doi.org/10.1051/0004-6361/202142624

TY - JOUR

T1 - A 2-3 mm high-resolution molecular line survey towards the centre of the nearby spiral galaxy NGC 6946

AU - Eibensteiner, C.

AU - Barnes, A. T.

AU - Bigiel, F.

AU - Schinnerer, E.

AU - Liu, D.

AU - Meier, D. S.

AU - Usero, A.

AU - Leroy, A. K.

AU - Rosolowsky, E.

AU - Puschnig, J.

AU - Lazar, I.

AU - Pety, J.

AU - Lopez, L. A.

AU - Emsellem, E.

AU - Bešlić, I.

AU - Querejeta, M.

AU - Murphy, E. J.

AU - Den Brok, J.

AU - Schruba, A.

AU - Chevance, M.

AU - Glover, S. C.O.

AU - Gao, Y.

AU - Grasha, K.

AU - Hassani, H.

AU - Henshaw, J. D.

AU - Jimenez-Donaire, M. J.

AU - Klessen, R. S.

AU - Kruijssen, J. M.D.

AU - Pan, H. A.

AU - Saito, T.

AU - Sormani, M. C.

AU - Teng, Y. H.

AU - Williams, T. G.

PY - 2022/3/1

Y1 - 2022/3/1

N2 - The complex physical, kinematic, and chemical properties of galaxy centres make them interesting environments to examine with molecular line emission. We present new 2-4″ (∼75-150 pc at 7.7 Mpc) observations at 2 and 3mm covering the central 50″ (∼1:9 kpc) of the nearby doublebarred spiral galaxy NGC6946 obtained with the IRAM Plateau de Bure Interferometer. We detect spectral lines from ten molecules: CO, HCN, HCO+, HNC, CS, HC3N, N2H+, C2H, CH3OH, and H2CO. We complemented these with published 1mm CO observations and 33 GHz continuum observations to explore the star formation rate surface density ΣSFR on 150 pc scales. In this paper, we analyse regions associated with the inner bar of NGC6946 - the nuclear region (NUC), the northern (NBE), and southern inner bar end (SBE) and we focus on short-spacing corrected bulk (CO) and dense gas tracers (HCN, HCO+, and HNC). We find that HCO+ correlates best with ΣSFR, but the dense gas fraction (fdense) and star formation efficiency of the dense gas (SFEdense) fits show different behaviours than expected from large-scale disc observations. The SBE has a higher ΣSFR, fdense, and shocked gas fraction than the NBE. We examine line ratio diagnostics and find a higher CO(2-1)/CO(1-0) ratio towards NBE than for the NUC. Moreover, comparison with existing extragalactic datasets suggests that using the HCN/HNC ratio to probe kinetic temperatures is not suitable on kiloparsec and sub-kiloparsec scales in extragalactic regions. Lastly, our study shows that the HCO+=HCN ratio might not be a unique indicator to diagnose AGN activity in galaxies.

AB - The complex physical, kinematic, and chemical properties of galaxy centres make them interesting environments to examine with molecular line emission. We present new 2-4″ (∼75-150 pc at 7.7 Mpc) observations at 2 and 3mm covering the central 50″ (∼1:9 kpc) of the nearby doublebarred spiral galaxy NGC6946 obtained with the IRAM Plateau de Bure Interferometer. We detect spectral lines from ten molecules: CO, HCN, HCO+, HNC, CS, HC3N, N2H+, C2H, CH3OH, and H2CO. We complemented these with published 1mm CO observations and 33 GHz continuum observations to explore the star formation rate surface density ΣSFR on 150 pc scales. In this paper, we analyse regions associated with the inner bar of NGC6946 - the nuclear region (NUC), the northern (NBE), and southern inner bar end (SBE) and we focus on short-spacing corrected bulk (CO) and dense gas tracers (HCN, HCO+, and HNC). We find that HCO+ correlates best with ΣSFR, but the dense gas fraction (fdense) and star formation efficiency of the dense gas (SFEdense) fits show different behaviours than expected from large-scale disc observations. The SBE has a higher ΣSFR, fdense, and shocked gas fraction than the NBE. We examine line ratio diagnostics and find a higher CO(2-1)/CO(1-0) ratio towards NBE than for the NUC. Moreover, comparison with existing extragalactic datasets suggests that using the HCN/HNC ratio to probe kinetic temperatures is not suitable on kiloparsec and sub-kiloparsec scales in extragalactic regions. Lastly, our study shows that the HCO+=HCN ratio might not be a unique indicator to diagnose AGN activity in galaxies.

KW - Galaxies: ISM

KW - Galaxies: individual: NGC 6946

KW - ISM: molecules

UR - http://www.scopus.com/inward/record.url?scp=85127612495&partnerID=8YFLogxK

U2 - 10.1051/0004-6361/202142624

DO - 10.1051/0004-6361/202142624

M3 - Article

SN - 0004-6361

VL - 659

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A173

ER -

A 2-3 mm high-resolution molecular line survey towards the centre of the nearby spiral galaxy NGC 6946

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