The MALATANG Survey : The L GAS-L IR Correlation on Sub-kiloparsec Scale in Six Nearby Star-forming Galaxies as Traced by HCN J = 4 → 3 and HCO + J = 4 → 3
Author
Tan, Qing-Hua
Gao, Yu
Zhang, Zhi-Yu
Greve, Thomas R.
Jiang, Xue-Jian
Wilson, Christine D.
Yang, Chen-Tao
Bemis, Ashley
Chung, Aeree
Matsushita, Satoki
Shi, Yong
Ao, Yi-Ping
Brinks, Elias
Currie, Malcolm J.
Davis, Timothy A.
Grijs, Richard de
Ho, Luis C.
Imanishi, Masatoshi
Kohno, Kotaro
Lee, Bumhyun
Parsons, Harriet
Rawlings, Mark G.
Rigopoulou, Dimitra
Rosolowsky, Erik
Bulger, Joanna
Chen, Hao
Chapman, Scott C.
Eden, David
Gear, Walter K.
Gu, Qiu-Sheng
He, Jin-Hua
Jiao, Qian
Liu, Dai-Zhong
Liu, Li-Jie
Li, Xiao-Hu
Michalowski, Michal J.
Nguyen-Luong, Quang
Qiu, Jian-Jie
Smith, Matthew W. L.
Violino, Giulio
Wang, Jian-Fa
Wang, Jun-Feng
Wang, Jun-Zhi
Yeh, Sherry
Zhao, Ying-He
Zhu, Ming
Attention
2299/20273
Abstract
We present HCN J = 4→3 and HCO+ J = 4→3 maps of six nearby star-forming galaxies, NGC 253, NGC 1068, IC 342, M82, M83, and NGC 6946, obtained with the James Clerk Maxwell Telescope as part of the MALATANG survey. All galaxies were mapped in the central 2×2 region at 14 (FWHM) resolution (corresponding to linear scales of ∼0.2-1.0 kpc). The LIR-Ldense relation, where the dense gas is traced by the HCN J = 4→3 and the HCO+ J = 4→3 emission, measured in our sample of spatially resolved galaxies is found to follow the linear correlation established globally in galaxies within the scatter. We find that the luminosity ratio, LIR/Ldense, shows systematic variations with LIR within individual spatially resolved galaxies, whereas the galaxy-integrated ratios vary little. A rising trend is also found between LIR/Ldense ratio and the warm-dust temperature gauged by the 70 μm/100 μm flux ratio. We find that the luminosity ratios of IR/HCN (4-3) and IR/HCO+ (4-3), which can be taken as a proxy for the star formation efficiency (SFE) in the dense molecular gas (SFE dense), appear to be nearly independent of the dense gas fraction ( f dense) for our sample of galaxies. The SFE of the total molecular gas (SFEmol) is found to increase substantially with f dense when combining our data with those on local (ultra)luminous infrared galaxies and high-z quasars. The mean LHCN(4-3) LHCO+(4-3) line ratio measured for the six targeted galaxies is 0.9±0.6. No significant correlation is found for the L'HCN(4-3) L'HCO+(4-3) ratio with the star formation rate as traced by L IR, nor with the warm-dust temperature, for the different populations of galaxies.
Publication date
2018-06-25Published in
The Astrophysical JournalPublished version
https://doi.org/10.3847/1538-4357/aac512Other links
http://hdl.handle.net/2299/20273Metadata
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