Universe Colloquium: Triggering and feedback from Active Galactic Nuclei

by Stanislav Shabala (U Tasmania)

Wednesday 1 Jul 2015, 16:30 → 17:30 Europe/Berlin

seminar room (Excellence Cluster Universe, Boltzmannstrasse 2, Garching)

Active Galactic Nuclei (AGN) play a key role in the formation and evolution of galaxies through so-called AGN feedback. Quantifying the magnitude (and even the sign) of this feedback, however, is difficult. Two effects play a key role in determining feedback efficiency: (1) the kinetic power of AGN jets, which set how much energy is available for feedback; and (2) the chronology of the AGN-starburst connection, which determines how promptly this energy is delivered to the surrounding gas. Stas will discuss different ways of measuring AGN kinetic power, and outline a recent approach in which they combine models describing the dynamical evolution of observable radio AGN properties with semi-analytic galaxy formation models. He will show how this technique can be used to derive the physical properties of low-redshift AGN, shedding light on processes driving AGN triggering and feedback. Stas will also present the latest results from their multi-wavelength study of a morphologically-selected sample of early-type galaxies with dust lanes, drawn from Galaxy Zoo. He will argue that gas-rich galaxy interactions are responsible for triggering radiatively efficient AGN in the local Universe. Using such a clean, morphologically-selected sample allows them to reconstruct the timeline linking star formation and AGN activity. They find that merger-triggered star formation precedes AGN triggering. These findings have important implications for both observational signatures of merger-triggered star formation and AGN activity, and the efficiency of AGN feedback. The Universe Colloquium is followed by a social gathering with wine and cheese.