PREDNASAJUCI / LECTURER :

Michal Zajaček

(1)  Masaryk University, Brno, Czechia

NAZOV / TITLE :

Stellar Eclipses of Nearby Galactic Nuclei: A New Probe of Supermassive Black
Holes

ABSTRAKT / ABSTRACT :

Nearby supermassive black holes are embedded in dense nuclear star clusters,
where individual stars may occasionally pass in front of the compact radio
core. Such stellar transits produce potentially detectable eclipses in the
radio light curves of low-luminosity active galactic nuclei, especially in the
millimeter domain. In this seminar, I will present the physical conditions
under which these events can be observed and discuss their expected
observational signatures across radio/mm frequencies. I will show how the
eclipse depth and duration depend on the size of the frequency-dependent radio
core and on the properties of the transiting star, and I will illustrate the
characteristic light-curve profiles expected for different orbital
configurations. I will also demonstrate that repeated eclipses provide a novel
way to constrain the mass of the central supermassive black hole and the
orbital properties of stars in the nuclear cluster. Finally, I will discuss
strategies for identifying these rare but valuable events in current and future
radio monitoring campaigns, including VLBI observations and Event Horizon
Telescope data, and highlight their potential as a new tool for probing the
immediate environments of nearby supermassive black holes.