The next Seminar of the Department of Astronomy will be held by dr Edi Bon, Senior Research Associate of the Astronomical Observatory, on topic of Secular spectroscopic variability of active galactic nuclei: from accretion and broad-line region response to binary supermassive black holes modeling.
Resume:
Our understanding of Active Galactic Nuclei (AGN) physics relies heavily on the study of their secular variability (long-term changes) that allow us to distinguish stochastic processes from the fundamental dynamics and evolution of these systems. Given that the dynamical timescales near supermassive black holes range from several decades to centuries, with viscous timescales being even longer, long-term monitoring is essential for distinguishing fundamental system dynamics from stochastic variations in their light curves.
In this talk, I will present how very long-term spectroscopic monitoring of AGN reveals the structure and physics of their cores. These studies have led to the identification of several spectroscopic supermassive binary black hole (SMBBH) candidates, for which we managed to constrain orbital parameters using their line shape variability. The talk further explores the physics behind extreme variability cases. We also examine the 'Changing Look' phenomenon through the lens of two distinct triggers: viscous instabilities in the inner disk and tidal interactions during the pericenter passage of eccentric SMBBHs.
The final part of the seminar will focus on a unique research opportunity for motivated students. We have recently obtained new Gemini spectroscopic observations of radio galaxies with curved jets ('bent-tail' quasars) discovered by the ASKAP radio telescope. The spectroscopic data are currently in raw form and await reduction and analysis. This creates a chance for students to work directly with fresh, unpublished, cutting-edge observations, from data reduction and spectral decomposition to scientific interpretation, with realistic prospects for co-authorship in leading international journals and the development of a basis for future PhD thesis topics.
The Seminar will be held at the Department of Astronomy of the Faculty of Mathematics in Belgrade, in the classroom 809, on Tuesday, March 3 2026, at 6 PM.