The Nature of the Dense Obscuring Material in the Nucleus of NGC~1068
Session 119 -- Starbursts and Seyfert 2s
Oral presentation, Saturday, January 15, 10:15-11:45, Crystal Forum Room (Crystal City Marriott)

[119.06] The Nature of the Dense Obscuring Material in the Nucleus of NGC~1068

L.J. Tacconi, M. Cameron, R.Genzel, A.I. Harris, S. Madden (Max-Planck-Institut f\"ur extraterrestrische Physik (MPE))

We present the results from 3$^{\prime \prime} \times$2$^{\prime \prime}$ observations of the nuclear region of NGC~1068 in the J=1-0 line of HCN obtained with the IRAM Interferometer on the Plateau de Bure, France. Our HCN map reveals the presence of a very strong, resolved nuclear source of about 4$^{\prime \prime}$ (280 pc at D=14 Mpc) in diameter, as well as clumps of gas associated with a star forming ring located at a radius of 15$^{\prime \prime}$ from the nucleus. We interpret the nuclear HCN source as a concentration of very dense (N(H$_2$)$\ge$10$^4$ cm$^{-3}$) molecular clouds (mass $\sim$5--10$\times$10$^7$ M$_\odot$) surrounding the active nucleus. The HCN velocity field clearly shows that the dense gas is rotating. Based on our kinematic analysis of the HCN data were infer that the disk-like structure producing the HCN emission has a low inclination. We also conclude that there are turbulent velocities present in excess of 100 km s$^{-1}$, indicating that the strucure is also very thick. Given this geometry we conclude that the HCN data do not support the current small-scale, dense torus models for unifying the two types of Seyfert galaxies.