Tsukuba Uchu Forum

135th Uchu Forum

New insights into active galactic nuclei using high-resolution submillimetre-wave observations

Takuma Izumi


Active Galactic Nuclei (AGN) shine brightly due to the gravitational energy released by mass accretion onto a supermassive black hole (SMBH). AGN are smoking guns of black hole growth. Recently, the Atacama Large Millimeter/submillimeter Array (ALMA), the world's most powerful submillimeter interferometer, has made it possible to study various properties of matter around AGN observationally with high sensitivity and resolution. In this talk, I will review a series of observational studies that our team has performed so far (mainly on AGN in the nearby universe). In particular, we have made a number of pioneering studies of circumnuclear disks (CNDs) at ~100 pc scale in the Galactic center and beyond. For example, (i) the CND is a direct mass source for SMBH growth, (ii) the physical and chemical composition of the CND scale gas is changed by the strong X-ray radiation of AGN, (iii) the complex dynamical structure of the multiphase interstellar medium (molecules, atoms, plasma) driven by AGN radiation is explained by the AGN torus (iii) the complex dynamical structure of multiphase interstellar material (molecules, atoms, and plasma) driven by AGN radiation causes the central core shielding phenomenon called AGN torus. Furthermore, (iv) in the latest study, we have finally achieved a high resolution of less than 1 pc in the AGN center, and directly detected and quantified the accretion flow to the SMBH. In addition to these research results, this talk will discuss a series of research proposals, including our planned observations using the James Webb Space Telescope (JWST) satellite (Cycle 2 proposal already accepted) and further high-resolution observations of the multiphase interstellar medium (ALMA Cycle 9 proposal already accepted/Cycle 10 proposal already accepted). (ALMA Cycle 9 proposal/Cycle 10 proposal) will also be introduced and future strategies will be discussed. Image