Dr. Davide Bevacqua (INAF-OAB)
11 March 2026
11:30, Aula Piazzi
Abstract:
In the standard paradigm of galaxy formation, high-z galaxies grow primarily through the accretion of gas from the cosmic web, which fuels star formation (SF) and the growth of the central supermassive black hole. Eventually, galaxies can run out of cold gas, stop their SF, and become quiescent. After quenching, galaxies can continue to interact with their environment and accrete cold gas. As a consequence, gas accretion can ignite new SF, causing rejuvenation, or fuel AGN activity. While this picture is indirectly supported by both theoretical and observational studies, direct evidence of ongoing gas accretion onto quiescent galaxies is quite rare and, to date, only a handful of cases in the nearby Universe have been reported, leaving the origin and fate of the accreted gas as open questions. In this talk, I will present the recent discovery of a massive quiescent galaxy at z ≈ 2.7 with spectroscopic evidence of neutral gas inflow. Remarkably, despite the strong inflow, the galaxy shows no evidence of SF over the past 1 Gyr and no strong AGN emission. This provides the first direct evidence that quiescent galaxies can replenish their gas content without triggering new star formation or AGN activity. I will discuss the potential sources of the inflowing gas, the possible reasons why the inflowing gas does not ignite star formation, and the implications for galaxy formation models.