In the local universe stars only make up about 7% of all baryons, indicating that star formation has been extremely inefficient across the cosmic epochs. Within this context, even more impressive is the fact that in a significant fraction of galaxies star formation has been totally “quenched”, resulting into the population of passive and quiescent local galaxies. Understanding what are the mechanisms responsible for suppressing or even quenching star formation in galaxies has been one of the main challenges of astrophysics in recent years and it is one of the research areas in which most of the efforts have been directed, both in terms of cosmological simulations and in terms of observing campaigns.
I will give an overview of the potential causes and physical processes that might be responsible for regulating or even leading to the complete suppression of star formation in galaxies. I will illustrate that there are a variety of possible culprits. Among these I will show that supernova explosions can play a role, but the energy injected in the insterstellar and intergalactic medium by accreting supermassive black holes can have a truly dramatic effect on their host galaxies. The environment in which galaxies live (e.g. galaxy groups or clusters) can also play an important role, by suppressing star formation especially in satellite galaxies. I will discuss observational evidence for these various effects by using results from extensive multi-wavelength datasets.
I will conclude by emphasizing open, outstanding problems and the possibility of tackling them with the next generation of observing facilities.
18/05/2021
The program QUID ULTRA? Frontiers and Controversies in Astrophysics is a series of monthly prestigious colloquia that will be
running from early February till December 2021. This initiative has been funded by Sapienza University with the co-sponsorship
of INAF/Astronomical Observatory of Rome and of the joint PhD program in Astronomy, Astrophysics and Space Science of Sapienza,
Tor Vergata University and INAF.
Due to the pandemic situation, the first 6 colloquia will be held online via zoom.
The scientific program and all the information on how to attend the meeting can be found on the project website: www.quidultra.it.
Looking forward to seeing you soon,
Raffaella Schneider (on behalf of the SOC)