SO-IAA Colloquium: Outflows and their feedback effect in galaxies

Galactic outflows are an essential component of galaxies' lifecycle. They regulate star formation and can even totally quench star formation in galaxies, hence transforming star forming galaxies into passive systems. I will review the properties of galactic outflows, their multi-phase nature, their driving mechanism, both in normal star forming galaxies and in galaxies hosting Active Galactic Nuclei, both in the local Universe and in primeval galaxies. I will show that the "ejective" mode is less effective than previously thought in quenching star formation in galaxies, in the sense that outflows are generally not really capable of cleaning galaxies of their gas content. However, outflows can contribute to heat their circumgalactic medium hence suppressing accretion of fresh gas, and therefore quenching galaxies as a consequence of "starvation". I will also show that, although galactic outflows are generally associated to negative feedback, they can also have a positive feedback effect, in the sense that they can also foster star formation. In particular, I will show recent evidences of star formation occurring inside galactic outflows. This phenomenon was predicted by recent models and could provide a new channel for the formation of the spheroidal component of galaxies.

14/11/2019 - 12:30
Dr. Roberto Maiolino
Kavli Institute for Cosmology, University of Cambridge