Dr. Christopher Harrison

Current galaxy formation theory requires that growing supermassive black holes (i.e., Active Galactic Nuclei; AGN) must “feedback” on the evolution of their host. This process is expected to work because the energy released by the AGN (in the form of jets, winds or radiation) is transferred into the host galaxy gas and ultimately inhibits star formation. However, although theoretically a convincing idea, this must be backed up by observations. I will outline our work approaching this problem with a multifaceted approach. Firstly, I will present our results from the Quasar Feedback Survey, which is a detailed multi-wavelength observational campaign of nearby (z~0.1) quasar host galaxies. Our radio imaging and integral field spectroscopy reveal a high prevalence of interactions between low power jets and the interstellar medium. This interaction appears to drive outflows and plumes of high velocity dispersion gas. Secondly, for high redshift (z~1-3) galaxies, both our detailed observations of individual galaxies and our global measurements of large samples of galaxies suggest that the impact of AGN on star formation is subtle and/or occurs on long timescales. Despite some strong counter claims in the literature, I will demonstrate that these results can still be reconciled with current expectations of AGN feedback models.