SO colloquio: A new look at the torus of active galactic nuclei

The classical picture to explain the observations of active galactic nuclei (AGN) required a geometrically and optically thick torus of molecular gas and dust to obscure the central engine from some lines of sight. For more than two decades, the torus was believed to be a compact (pc-scale), isolated, and rotating structure. Our recent work in the Galactic Activity, Torus, and Outflow Survey (GATOS), using ALMA and high-angular resolution mid-infrared observations has forever changed the picture of the torus and its immediate surroundings. ALMA has revealed AGN tori with sizes of a few tens of parsecs, which are now observed as rotating and sometimes outflowing structures. In this talk, I will present high angular resolution mid-IR observations of nearby GATOS Seyfert galaxies, including some recently taken with JWST/MIRI, and compare them with ALMA observations. I will also show newly generated-radiative transfer disk+wind models and model images, aimed at interpreting and modelling our observations. In more than half of our sample, we find that the extended mid-infrared emission is typically in the polar direction and perpendicular to the ALMA-detected tori. The Eddington ratios and nuclear hydrogen column densities of these GATOS Seyferts are favorable to launching polar and/or equatorial dusty winds, according to numerical simulations. Our results provide observational support for the torus+wind scenario. The wind component is more relevant at high Eddington ratios and/or AGN luminosities, and polar dust emission is predicted at moderate nuclear column densities. The torus or disk component, on the other hand, prevails at low luminosities and/or Eddington ratios.

27/10/2022 - 12:30
Dr. Almudena Alonso Herrero
Centro de Astrobiología, CSIC-INTA, Spain