アブストラクト：
"ALMA observations revealed the presence of circumnuclear gas in the innermost parsecs of nearby galaxies, where the gravity can be dominated by a supermassive black hole (SMBH). The circumnuclear gas may form through the infall and disruption of molecular clouds. This scenario has been proposed to explain the circumnuclear ring and even the young stellar disk in our Galactic center. However, it is not straightforward to predict the result of similar episodes in nearby galactic nuclei, where the mass of the SMBH and that of the nuclear star cluster -if present- can be quite different than in the Milky Way. Therefore, I present the first systematic study on the formation of circumnuclear ring/disks in galactic nuclei by means of smoothed particle hydrodynamics simulations. I show that the morphology of circumnuclear gas can show distinct features of the presence of the SMBH, displaying a disk structure in SMBH dominated GNs and ring-like structures in NSC dominated GNs. This is also in agreement with the properties of the Milky Way’s CNR, which orbits just outside the SMBH sphere of influence."