Aperture Synthesis Images of Dense Molecular Gas in Nearby Galaxies with the Nobeyama Millimeter Array
| dc.creator | Kohno, Kotaro | |
| dc.creator | Kawabe, Ryohei | |
| dc.creator | Shibatsuka, Toshihito | |
| dc.creator | Matsushita, Satoki | |
| dc.date | 1999-09-24 | |
| dc.date.accessioned | 2026-07-25T13:43:11Z | |
| dc.description | In order to study the distribution of dense molecular gas and its relation to the central activities (starburst and AGN) in galaxies, we have conducted an imaging survey of HCN(1-0) and HCO+(1-0) emissions from nearby spiral galaxies with the Nobeyama Millimeter Array. In starburst galaxies, we find that there is good spatial coincidence between dense molecular gas and star-forming regions. The ratios of HCN to CO integrated intensities on the brightness temperature scale, R(HCN/CO), are as high as 0.1 to 0.2 in the starburst regions, and quickly decrease outside of these regions. In contrast, we find a remarkable decrease of the HCN emission in the post-starburst nuclei, despite the strong CO concentrations there. The R(HCN/CO) values in the central a few 100 pc regions of these quiescent galaxies are very low, 0.02 to 0.04. A rough correlation between R(HCN/CO) and Ha/CO ratios, which is an indicator of star formation efficiency, is found at a few 100 pc scale. The fraction of dense molecular gas in the total molecular gas, measured from R(HCN/CO), may be an important parameter that controls star formation. In some Seyfert galaxies we find extremely high R(HCN/CO) exceeding 0.3. These very high ratios are never observed even in strong starburst regions, implying a physical link between extremely high R(HCN/CO) and Seyfert activity. | |
| dc.description | 2 pages, 1 figure, to appear in the proceedings of ``Imaging at Radio through Submillimeter Wavelengths'', held at Tucson, AZ, June 6-9, 1999, ed. J. Mangum (ASP: San Francisco) | |
| dc.identifier | https://arxiv.org/abs/astro-ph/9909422 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/9909422 | |
| dc.identifier.uri | https://dspace.dare.co.zw/handle/123456789/19711 | |
| dc.subject | Astrophysics | |
| dc.title | Aperture Synthesis Images of Dense Molecular Gas in Nearby Galaxies with the Nobeyama Millimeter Array | |
| dc.type | text |