Examinando por Autor "Bongiorno, A."
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Ítem BAT AGN Spectroscopic Survey – XIX. Type 1 versus type 2 AGN dichotomy from the point of view of ionized outflows(Oxford University Press, 2019-11) Rojas, A.F; Sani, E.; Gavignaud, I.; Ricci, C.; Lamperti, I.; Koss, M.; Trakhtenbrot, B.; Schawinski, K.; K., Oh.; Bauer, F. E.; Bischetti, M.; Boissay-Malaquin, R.; Bongiorno, A.; Harrison, F.; Kakkad, A.D; Masetti, N.; Ricci, F.; Shimizu, T.; Stalevski, M.; Stern, D.; Vietri, G.We present a detailed study of ionized outflows in a large sample of ∼650 hard X-raydetected active galactic neuclei (AGNs). Using optical spectroscopy from the BAT AGN Spectroscopic Survey (BASS), we are able to reveal the faint wings of the [OIII] emission lines associated with outflows covering, for the first time, an unexplored range of low AGN bolometric luminosity at low redshift (z ∼0.05).We test if and how the incidence and velocity of ionized outflow is related to AGN physical parameters: black hole mass (MBH), gas column density (NH), Eddington ratio (λEdd), [O III], X-ray, and bolometric luminosities. We find a higher occurrence of ionized outflows in type 1.9 (55 per cent) and type 1 AGNs (46 per cent) with respect to type 2 AGNs (24 per cent). While outflows in type 2 AGNs are evenly balanced between blue and red velocity offsets with respect to the [OIII] narrow component, they are almost exclusively blueshifted in type 1 and type 1.9 AGNs. We observe a significant dependence between the outflow occurrence and accretion rate, which becomes relevant at high Eddington ratios [log(λEdd) −1.7]. We interpret such behaviour in the framework of covering factor-Eddington ratio dependence. We do not find strong trends of the outflow maximum velocity with AGN physical parameters, as an increase with bolometric luminosity can be only identified when including samples of AGNs at high luminosity and high redshift taken from literature.Ítem Seeking for the leading actor on the cosmic stage: Galaxies versus supermassive black holes(Hindawi Limited, 2012) Bongiorno, A.; Shankar, F.; Civano, F.; Gavignaud, I.; Georgakakis, A.A major development in extragalactic astrophysics in recent years has been the realization that active galactic nuclei (AGN), which signpost accretion events onto supermassive black holes (SMBHs) [1, 2], may play a fundamental role in the formation and evolution of galaxies. Understanding the physics that drive the growth of SMBH across cosmic time is therefore important for having a complete picture of galaxy formation. The two processes of galaxy and BH evolution can no longer be regarded as separate, as was the case until about 10 years ago, but need to be studied in conjunction.Ítem The cosmic growth of the active black hole population at 1 < z < 2 in zCOSMOS, VVDS and SDSS(Oxford University Press, 2015-03) Schulze, A.; Bongiorno, A.; Gavignaud, I.; Schramm, M.; Silverman, J.; Merloni, A.; Zamorani, G.; Hirschmann, M.; Mainieri, V.; Wisotzki, L.; Shankar, F.; Fiore, F.; Koekemoer, A.M.; Temporin, G.We present a census of the active black hole population at 1 < z < 2, by constructing the bivariate distribution function of black hole mass and Eddington ratio, employing a maximum likelihood fitting technique. The study of the active black hole mass function (BHMF) and the Eddington ratio distribution function (ERDF) allows us to clearly disentangle the active galactic nuclei (AGN) downsizing phenomenon, present in the AGN luminosity function, into its physical processes of black hole mass downsizing and accretion rate evolution. We are utilizing type-1 AGN samples from three optical surveys (VVDS, zCOSMOS and SDSS), that cover a wide range of 3 dex in luminosity over our redshift interval of interest. We investigate the cosmic evolution of the AGN population as a function of AGN luminosity, black hole mass and accretion rate. Compared to z = 0, we find a distinct change in the shape of the BHMF and the ERDF, consistent with downsizing in black hole mass. The active fraction or duty cycle of type-1 AGN at z ~ 1.5 is almost flat as a function of black hole mass, while it shows a strong decrease with increasing mass at z = 0. We are witnessing a phase of intense black hole growth, which is largely driven by the onset of AGN activity in massive SMBHs (supermassive black holes) towards z = 2. We finally compare our results to numerical simulations and semiempirical models and while we find reasonable agreement over certain parameter ranges, we highlight the need to refine these models in order to match our observations. © 2015 The Authors.