Drivers of black hole growth and galaxy evolution
In his thesis, Antonio La Marca investigates how galaxies and their central supermassive black holes grow together over cosmic time. Every massive galaxy hosts a black hole at its centre, and when gas falls into it, the system shines as an active galactic nucleus (AGN). Understanding how this gas is funnelled inward is key to explaining how galaxies evolve.
La Marca combines large multi-wavelength surveys with state-of-the-art artificial intelligence (AI) to identify the physical mechanisms that trigger AGN activity. La Marca analyses the role of galaxy mergers (collisions between galaxies of similar mass) and internal, slower processes such as galactic bars, which can channel gas toward the centre, in the low redshift Universe. La Marca also focuses on the role of galaxy mergers in the younger Universe. This investigation shows that such interactions efficiently feed powerful AGN, while internal processes mainly sustain lower-luminosity AGN in more relaxed galaxies. Finally, La Marca explores a different galaxy classification, based on stellar kinematics. This additional work introduces AI-based techniques to infer galaxy kinematics directly from imaging data.
A major methodological advance of the thesis is the development of deep-learning tools to classify galaxies and detect subtle morphological features in vast astronomical datasets, including those from the James Webb Space Telescope and Euclid. Moreover, the use of the first Euclid data enabled the first statistically relevant analysis of the galaxy merger-AGN connection.
Overall, La Marca concludes that there are two different black hole fuelling pathways: violent, merger-driven accretion producing the most luminous AGN, and bar-driven inflows responsible for more moderate activity. These findings establish a dual framework for understanding how galaxies and their black holes co-evolve across cosmic history.