吳俊輝臺灣大學：天文物理研究所謝佩穎Hsieh, Pei-YingPei-YingHsieh2007-11-262018-06-282007-11-262018-06-282006http://ntur.lib.ntu.edu.tw//handle/246246/52032The first 12CO(J=2-1) interferometric image of the Seyfert 1 galaxy NGC 1097 is presented in this work. The 12CO(J=2-1) map shows a strong nuclear concentration coincident with the Seyfert nucleus, and a molecular ring corresponding to the starburst ring shown in optical images. The 12CO(J=2-1)/(J=1-0) intensity ratio of the nuclear concentration is up to 1.95+-0.14 and it suggests that the physical condition of the central molecular gas is warm (>250 K) and dense (~10^4 cm^-3). A velocity map shows that the nuclear molecular gas is rotating with the molecular ring in the same sense, while its velocity gradient is much steeper than that of the ring. This steep velocity gradient at the central molecular gas can be interpreted as a highly-inclined disk or low-inclined disk with small radius. In the case of the highly-inclined disk, it could be clumpy, or warped, or with large truncation between AGN and torus to see through the AGN. In the case of the low-inclined disk, its size has to be small enough to explain the steep velocity gradient. The molecular ring is a site of starburst judged by a physical conditions relatively warmer and denser than the GMCs, and an analysis of Toomre instability suggests star formation in the ring. The origin of the ring may be attributed to Lindblad resonance, which is suggested by the hydrodynamical simulation.Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . . . iii Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . v List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii 1 INTRODUCTION 1 1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 NGC 1097 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 OBSERVATIONS AND DATA REDUCTION 9 3 RESULTS 14 3.1 12CO(J=2-1) Emission . . . . . . . . . . . . . . . . . . . . . . 14 3.2 Kinematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 3.2.1 Velocity Distribution . . . . . . . . . . . . . . . . . . . 21 3.2.2 Position-Velocity Diagram . . . . . . . . . . . . . . . . 25 3.2.3 Rotation Curve . . . . . . . . . . . . . . . . . . . . . . 27 3.3 Line Ratios . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 3.4 Mass Distribution . . . . . . . . . . . . . . . . . . . . . . . . 36 4 DISCUSSIONS 38 4.1 Physical conditions of the circumnuclear gas . . . . . . . . . . 38 4.1.1 Local Thermal Equilibrium (LTE) . . . . . . . . . . . . 39 4.1.2 Large Velocity Gradient (LVG) . . . . . . . . . . . . . 42 4.2 Nuclear gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 4.2.1 Nature of the nuclear gas . . . . . . . . . . . . . . . . . 52 4.2.2 Is the circumnuclear gas the hypothetical circumnu- clear torus? . . . . . . . . . . . . . . . . . . . . . . . . 53 4.3 Molecular Ring . . . . . . . . . . . . . . . . . . . . . . . . . . 55 4.3.1 Is the molecular ring related to the starburst ring? . . 55 4.3.2 Lifetime of the molecular ring . . . . . . . . . . . . . . 55 4.3.3 Origin of the molecular ring . . . . . . . . . . . . . . . 56 5 SUMMARY 60 A Radiation Transfer 653314845 bytesapplication/pdfen-US星系活躍星系核星系間介質galaxyAGNISMotherhttp://ntur.lib.ntu.edu.tw/bitstream/246246/52032/1/ntu-95-R93244008-1.pdf