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| Paper: |
High-Density and Temperature Molecular Gas at the Centers of M51 and NGC 1068 |
| Volume: |
249, The Central Kiloparsec of Starbursts and AGN: the La Palma Connection |
| Page: |
727 |
| Authors: |
Vila-Vilaró, Baltasar; Butner, Harold M.; Bieging, John H.; Matsushita, Satoki; Kohno, Kotaro |
| Abstract: |
We have used the HHT submm telescope at the SMTO to observe the CO (7 --> 6) emission in the central regions of NGC 1068 and M51. Both targets were selected for their very high HCN (1 --> 0)/CO (1 --> 0) and HCN (1 --> 0) / 13CO (1 --> 0) nuclear ratios, which seem to suggest the presence of dense and high-temperature gas in those regions. Since CO (7 --> 6) has a similar critical density to that of HCN (1 --> 0) and requires a kinetic temperature of about 200 K to be thermalized, it is an excellent tracer of very warm and dense gas regions. Neither of the two targets was detected in this line, which suggests either lower temperatures than previously claimed or that the nuclear molecular medium is quite clumpy. |
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