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Hunting for large scale nuclear outflows: AGNs in the "forbidden zone"

Vincenzo MAINIERI
(ESO)

A key ingredient in many models for galaxy formation is an energetic kpc scale outflow powered by AGN activity to regulate and suppress star-formation in massive galaxies. However, observational evidence of these outflows at z>1 are mostly limited to rare radio-loud AGN, and therefore mostly kinetic energy from the jet. There are very few cases of kpc scale radiatively-driven outflows detected in non local radio-quiet AGN. We initiated a systematic search for the "ideal" AGN candidates to observe energetic large scale outflows. First we selected AGN with high mass accretion rates, since radiatively-driven winds likely originate from the acceleration of disk outflows by the AGN radiation field. An additional selection criteria comes from an indirect evidence of the effect of the radiation pressure generated by the central SMBH on its surroundings: the amount of cold gas responsible for the nuclear obscuration (NH) is connected with the level of AGN feedback. Due to the effect of the dust component of the gas in enhancing the interaction between the radiation generated by accretion on the SMBH and the gas itself (Fabian et al. 2006), long lived clouds would avoid the region of intermediate NH (10^22-10^23 cm^-2) and L_bol/L_Edd > 0.1, where the AGN would be super-Eddington for cold dusty gas. Any object found in this "forbidden zone" should be outflowing gas and therefore it could be used to test radiative feedback. We will report the first results of our search based on ~2500 X-ray selected AGN in the COSMOS field. We will discuss the overall properties of the selected candidates, first hints of their impact on the host galaxy and way forward to further constraint the presence of kpc scale radiatively-driven outflows.


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