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| Paper: |
Submillimeter ALMA Observations of the Dense Gas in the Type-1 Active Nucleus of NGC 1097 and NGC 7469 for a Robust Energy Diagnostic |
| Volume: |
499, Revolution in Astronomy with ALMA: The Third Year |
| Page: |
113 |
| Authors: |
Izumi, T. |
| Abstract: |
We present the 100 pc scale views of the dense molecular gas in the central kpc regions of nearby galaxies hosting a type-1 active galactic nucleus (AGN), NGC 1097 and NGC 7469, traced by HCN(4-3), HCO+(4-3), CS(7-6), and CO(3-2) lines, based on our ALMA cycle 0 and 1 observations. We supplemented our observations with data from literature and found enhanced ratios of HCN(4-3)/HCO+(4-3) and HCN(4-3)/CS(7-6) in AGNs, compared to starburst galaxies, which can be used as a new diagnostic method of galactic energy sources. Although several mechanisms can lead to different line ratios, our non-LTE analysis using multi-J interferometric data of NGC 1097 revealed a high [HCN]/[HCO+] abundance ratio in the nucleus. Interestingly, the HCN(4-3)/HCO+(4-3) line ratio in NGC 7469 is just as half as that in NGC 1097, although AGN luminosity of NGC 7469 is ∼ 1000 times higher than that of NGC 1097. We interpret these results qualitatively in the framework of high temperature chemistry and a receding XDR model. |
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