演講資訊

摘要：

Active Galactic Nuclei (AGNs) are found in some galactic nuclei, but super-massive black holes (SMBHs), which power the AGNs when combined with accretion disks, are known to exist in essentially all galactic nuclei in the universe. Therefore, AGNs, as well as SMBHs, should play some very important roles in galaxy evolution from very early to present-day universe, and understanding of nature of the AGNs themselves (e.g., an unification theory of AGN types) and also their influence on the host galaxies (e.g., AGN feedback) is of fundamental importance. In this talk, I will present our recent works on two very nearby galaxies suspected/known to host AGNs, NGC 3256 (at 35 Mpc) and M51 (at 7 Mpc). Our approach is to (1 for NGC 3256) explore AGN signatures that have been missed in a local luminous infrared galaxy in an advanced stage of the merging process of two galaxies, and (2 for M51) study in detail a very nearby AGN and its circumnuclear region at 10-100 pc scale. In both cases, we utilized observations in mid infrared, where AGN signatures can be detected more easily than in other wavelengths. I will describe our findings about these two AGNs, and discuss the implications.