From 22 to 25 July 2024, the Torino Planetarium hosted the annual conference of the international scientific collaboration dealing with Active Galactic Nuclei (AGN) in the framework of the “Legacy Survey of Space and Time” (LSST) project, the survey of the entire southern sky that will be carried out by the Observatory named after the American astronomer Vera C. Rubin.

AGN are the heart of some galaxies from which such a quantity of energy emanates that it can only be explained by assuming that it comes from the accretion of matter onto a supermassive black hole, with a mass equal to at least a million times that of the Sun, but which can also reach tens of billions of times the Sun. The start of the LSST survey is scheduled for next year and its duration of ten years, during which each portion of the sky will be observed every three days, promises to revolutionise our knowledge of the cosmos.

The Torino conference, entitled “Catching supermassive black holes with Rubin-LSST: Towards novel insights and discoveries into AGN science” was organized by Claudia M. Raiteri and Maria Isabel Carnerero from INAF-Osservatorio Astrofisico di Torino and Massimo Brescia from the Federico II University of Naples and brought together about fifty scientists from all over the world. The main goal was to discuss and collaboratively plan the studies that will be possible to conduct when the survey starts. One topic of discussion was how to identify AGN, in particular with machine learning methods. A session was dedicated to AGN in binary systems, predicted by theories of galaxy formation and evolution. Many talks focused on the analysis of the variability of AGN emission, which generally has a stochastic behaviour. We also
discussed about AGN that change their spectral appearance and about “reverberation mapping” techniques, which allow us to measure the spatial extension of the accretion disk surrounding the central black hole and that of the broad line region, the nuclear zone that produces the broad lines we observe in the spectra. One session focused on blazars, a class of AGN characterised by a jet of
plasma that points in our direction, amplifying their brightness and variability due to relativistic effects. We also discussed how it is possible to determine the “photometric redshift”, that is, the distance of the observed AGN, with the Rubin-LSST data. Finally, possible synergies with other astronomical investigation tools were presented, such as the legacy of the Gaia satellite in the optical band, or the observations of the eROSITA satellite in X-rays, or those of the new detectors at very high energies such as CTA.