An imaging survey of CO(1-0), HCN(1-0), and HCO+(1-0) lines in the centers of nearby Seyfert galaxies has been conducted using the Nobeyama Millimeter Array and the RAINBOW interferometer. Preliminary results reveal that 3 Seyferts out of 7 show abnormally high HCN/CO and HCN/HCO+ ratios, which cannot occur even in nuclear starburst galaxies. We suggest that the enhanced HCN emission originated from X-ray irradiated dense obscuring tori, and that these molecular line ratios can be a new diagnostic tool to search for ``pure'' AGNs. According to our HCN diagram, we suggest that NGC 1068, NGC 1097, and NGC 5194 host ``pure'' AGNs, whereas Seyfert nuclei of NGC 3079, NGC 6764, and NGC 7469 may be ``composite'' in nature.
@article{arxiv.astro-ph/0206398,
title = {Dense Molecular Gas and Star Formation in Nearby Seyfert Galaxies},
author = {K. Kohno and S. Matsushita and B. Vila-Vilaro and S. K. Okumura and T. Shibatsuka and M. Okiura and S. Ishizuki and R. Kawabe},
journal= {arXiv preprint arXiv:astro-ph/0206398},
year = {2007}
}
Comments
6 pages, 5 figures, in ASP Conf. Ser., 249, The Central kpc of Starbursts and AGN, 672, typo corrected