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Dense Gas and Star ...
Dense Gas and Star Formation in Nearby Infrared-bright Galaxies: APEX Survey of HCN and HCO+ J=2 -> 1
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- Zhou, Jing (författare)
- Nanjing University
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- Zhang, Zhi-Yu (författare)
- Nanjing University
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- Gao, Yu (författare)
- Xiamen University,Chinese Academy of Sciences
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- Wang, Junzhi (författare)
- Guangxi University,Chinese Academy of Sciences
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- Shi, Yong (författare)
- Nanjing University
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- Gu, Qiusheng (författare)
- Nanjing University
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- Yang, Chentao, 1988 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Wang, Tao (författare)
- Nanjing University
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- Tan, Qing-Hua (författare)
- Chinese Academy of Sciences
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(creator_code:org_t)
- 2022-08-30
- 2022
- Engelska.
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 936:1
- Relaterad länk:
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https://doi.org/10.3...
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Abstract
Ämnesord
Stäng
- Both Galactic and extragalactic studies of star formation suggest that stars form directly from dense molecular gas. To trace such high volume density gas, HCN and HCO+ J = 1 -> 0 have been widely used for their high dipole moments, relatively high abundances, and often being the strongest lines after CO. However, HCN and HCO+ J = 1 -> 0 emission could arguably be dominated by the gas components at low volume densities. The HCN J = 2 -> 1 and HCO+ J = 2 -> 1 transitions, with more suitable critical densities (1.6 x 10(6) and 2.8 x 10(5) cm(-3)) and excitation requirements, would trace typical dense gas closely related to star formation. Here we report new observations of HCN J = 2 -> 1 and HCO+ J = 2 -> 1 toward 17 nearby infrared-bright galaxies with the APEX 12 m telescope. The correlation slopes between the luminosities of HCN J = 2 -> 1 and HCO+ J = 2 -> 1 and total infrared emission are 1.03 +/- 0.05 and 1.00 +/- 0.05, respectively. The correlations of their surface densities, normalized with the area of radio/submillimeter continuum, show even tighter relations (slopes: 0.99 +/- 0.03 and 1.02 +/- 0.03). The eight active galactic nucleus (AGN)-dominated galaxies show no significant difference from the 11 star-formation-dominated galaxies in the above relations. The average HCN/HCO+ ratios are 1.15 +/- 0.26 and 0.98 +/- 0.42 for AGN- and star-formation-dominated galaxies, respectively, without obvious dependencies on infrared luminosity, dust temperature, or infrared pumping. The Magellanic Clouds roughly follow the same correlations, expanding to 8 orders of magnitude. On the other hand, ultraluminous infrared galaxies with AGNs systematically lie above the correlations, indicating potential biases introduced by AGNs.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
- NATURVETENSKAP -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)
- NATURVETENSKAP -- Fysik -- Den kondenserade materiens fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Condensed Matter Physics (hsv//eng)
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Zhou, Jing
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Zhang, Zhi-Yu
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Gao, Yu
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Wang, Junzhi
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Shi, Yong
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Gu, Qiusheng
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Yang, Chentao, 1 ...
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Wang, Tao
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Tan, Qing-Hua
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