The lifecycles of powerful radio galaxies: Triggering and feedback

I review the links between host galaxy evolution and quasar/jet activity in radio galaxies from an observational standpoint. Observations of the warm ionized gas provide evidence for powerful outflows in both the extended emission line regions (EELR: 5 < r < 100 kpc) and the narrow line regions (NLR: r < 5 kpc) that are capable of directly influencing the evolution of the stellar populations in the host galaxies. There is also evidence that the distribution of circum-nuclear ISM undergoes significant evolution as the radio jets expand through the central bulges of the hosts. On the other hand, results for the young stellar populations in the host galaxies provide key information about the triggering merger events. They indicate that there can be a significant time lag between the major episode of merger-induced star formation and triggering of the radio jets, and that some ultraluminous infrared galaxies may evolve into radio galaxies.