Special Universe Talk: Quasar feedback in the form of powerful outflows: recent results and perspectives

by Marcella Brusa (U Bologna)

Thursday 10 Jul 2014, 15:00 → 16:00 Europe/Berlin

Old seminar room, ground floor (MPI für extraterrestrische Physik (MPE), Giessenbachstrasse 1, Garching)

Update: Change of date, time and place! Quasar feedback on host galaxies in the form of powerful outflows is invoked as a key mechanism to quench star formation in massive galaxies, but direct observational evidences are still scarce and the debate on the physical origin of the observed outflows is still open. In this talk Marcella will review the observational constraints on the existence and origin of this mechanism, and present new X-shooter@VLT observations of a representative sample of 10 luminous, X-ray obscured QSOs at z~1.5 from the XMM-COSMOS survey, expected to be caught in the transitioning phase from starburst to AGN dominated systems. From the rest-frame optical spectra we could infer the presence of outflows in 6 out of 8 sources. This may be considered as a compelling indication that the color selection applied to our X-ray sample is effective in picking up objects in the outflowing phase. A comparison of the outflow energetic with the AGN luminosity and the kinetic energy associated to stellar processes, suggest that the AGN rather than the on-going star-formation may be the major driver for the presence of the observed broad and shifted components. In the two brightest sources we were also able to probe, via slit resolved spectroscopy, that the outflows extend up to 10 kpc scales. Most important, thanks to SINFONI data available for one of these 2 targets (XID2028) we were able to probe the presence of both positive and negative outflow-induced feedback in the host galaxy of the powerful QSO. Further perspective of studies with spatially resolved NIR spectroscopy and in the millimiter bands (e.g. ALMA, IRAM) to assess definitely the energetics of the outflows will also be discussed.