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The MALATANG Survey: Dense Gas and Star Formation from High Transition HCN and HCO+ maps of NGC253

Authors :
Jiang, Xue-Jian
Greve, Thomas R.
Gao, Yu
Zhang, Zhi-Yu
Tan, Qinghua
de Grijs, Richard
Ho, Luis C.
Michalowski, Michal J.
Currie, Malcolm J.
Wilson, Christine D.
Brinks, Elias
Ao, Yiping
Zhao, Yinghe
He, Jinhua
Harada, Nanase
Yang, Chentao
Jiao, Qian
Chung, Aeree
Lee, Bumhyun
Smith, Matthew W. L.
Liu, Daizhong
Matsushita, Satoki
Shi, Yong
Imanishi, Masatoshi
Rawlings, Mark G.
Zhu, Ming
Eden, David
Davis, Timothy A.
Li, Xiaohu
Jiang, Xue-Jian
Greve, Thomas R.
Gao, Yu
Zhang, Zhi-Yu
Tan, Qinghua
de Grijs, Richard
Ho, Luis C.
Michalowski, Michal J.
Currie, Malcolm J.
Wilson, Christine D.
Brinks, Elias
Ao, Yiping
Zhao, Yinghe
He, Jinhua
Harada, Nanase
Yang, Chentao
Jiao, Qian
Chung, Aeree
Lee, Bumhyun
Smith, Matthew W. L.
Liu, Daizhong
Matsushita, Satoki
Shi, Yong
Imanishi, Masatoshi
Rawlings, Mark G.
Zhu, Ming
Eden, David
Davis, Timothy A.
Li, Xiaohu
Publication Year :
2020

Abstract

To study the high-transition dense-gas tracers and their relationships to the star formation of the inner $\sim$ 2 kpc circumnuclear region of NGC253, we present HCN $J=4-3$ and HCO$^+ J=4-3$ maps obtained with the James Clerk Maxwell Telescope (JCMT). With the spatially resolved data, we compute the concentration indices $r_{90}/r_{50}$ for the different tracers. HCN and HCO$^+$ 4-3 emission features tend to be centrally concentrated, which is in contrast to the shallower distribution of CO 1-0 and the stellar component. The dense-gas fraction ($f_\text{dense}$, traced by the velocity-integrated-intensity ratios of HCN/CO and HCO$^+$/CO) and the ratio $R_\text{31}$ (CO 3-2/1-0) decline towards larger galactocentric distances, but increase with higher SFR surface density. The radial variation and the large scatter of $f_\text{dense}$ and $R_\text{31}$ imply distinct physical conditions in different regions of the galactic disc. The relationships of $f_\text{dense}$ versus $\Sigma_\text{stellar}$, and SFE$_\text{dense}$ versus $\Sigma_\text{stellar}$ are explored. SFE$_\text{dense}$ increases with higher $\Sigma_\text{stellar}$ in this galaxy, which is inconsistent with previous work that used HCN 1-0 data. This implies that existing stellar components might have different effects on the high-$J$ HCN and HCO$^+$ than their low-$J$ emission. We also find that SFE$_\text{dense}$ seems to be decreasing with higher $f_\text{dense}$, which is consistent with previous works, and it suggests that the ability of the dense gas to form stars diminishes when the average density of the gas increases. This is expected in a scenario where only the regions with high-density contrast collapse and form stars.<br />Comment: accepted to MNRAS

Details

Database :
OAIster
Publication Type :
Electronic Resource
Accession number :
edsoai.on1176397457
Document Type :
Electronic Resource
Full Text :
https://doi.org/10.1093.mnras.staa794