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STScI Webcast

2017 Hot Sci @ STScI

Observational signatures of AGN feedback across cosmic time

Presented by: Dominika Wylezalek (JHU)
Category: Science Colloquia   Duration: 1 hour   Broadcast date: August 23, 2017
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Feedback from accreting supermassive black holes is now a standard ingredient in galaxy formation models. But while many compelling models of AGN feedback exist, there is no clear data-driven picture of how AGN-driven winds are launched, how they propagate through the galaxy and what impact they have on the galactic gas. Recent work suggests that AGN luminosity plays an important role. In my talk I will describe recent efforts in our group to understand the power, reach and impact of feedback processes exerted by AGN across cosmic time. By relating feedback signatures in powerful quasars to the specific star formation rate in their host galaxies, we have found one of the first observational evidence that such outflows can indeed suppress star formation in their host galaxies. This is consistent with the AGN having a `negative’ impact through feedback on the galaxies' star formation history. Feedback signatures seem to be best observable in gas-rich galaxies where the coupling of the AGN-driven wind to the gas is strongest, in agreement with recent simulations. But how and where does this quenching happen? Upcoming observations with ALMA will tackle some of these outstanding questions. Furthermore, I will show that AGN signatures and AGN-driven winds can be easily hidden and not be apparent in the integrated spectrum of a galaxy hosting a low/intermediate-luminosity AGN. Using data from the new SDSS-IV MaNGA survey, we have developed a new AGN selection algorithm tailored to IFU data and we are uncovering a much more nuanced picture of AGN activity allowing us to discover AGN signatures at large distances from the galaxy center. This implies that large IFU surveys, such as the SDSS-IV MaNGA survey, might uncover many previously unknown AGN and feedback signatures related to them. Outflows and feedback from low- and intermediate-luminosity AGN might have been underestimated in the past but can potentially significantly contribute to the AGN/host-galaxy self-regulation. Finally, I will describe how JWST will revolutionize our understanding of the action of AGN feedback and the role of AGN feedback in galaxy evolution.