Browsing by Author "Ananna, T. T."

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    Accretion history of AGNs. III. Radiative efficiency and AGN contribution to reionization
    (2020) Ananna, T. T.; Urry, C. M.; Treister, Ezequiel; Hickox, R. C.; Shankar, F.; Ricci, Claudio; Cappelluti, N.; Marchesi, S.; Turner, T. J.
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    BASS XXXVII: The Role of Radiative Feedback in the Growth and Obscuration Properties of Nearby Supermassive Black Holes
    (2022) Ricci, C.; Ananna, T. T.; Temple, M. J.; Urry, C. M.; Koss, M. J.; Trakhtenbrot, B.; Ueda, Y.; Stern, D.; Bauer, F. E.; Treister, E.; Privon, G. C.; Oh, K.; Paltani, S.; Stalevski, M.; Ho, L. C.; Fabian, A. C.; Mushotzky, R.; Chang, C. S.; Ricci, F.; Kakkad, D.; Sartori, L.; Baer, R.; Caglar, T.; Powell, M.; Harrison, F.
    We study the relation between obscuration and supermassive black hole (SMBH) accretion using a large sample of hard X-ray selected active galactic nuclei (AGNs). We find a strong decrease in the fraction of obscured sources above the Eddington limit for dusty gas (log lambda(Edd) >= -2) confirming earlier results, and consistent with the radiation-regulated unification model. This also explains the difference in the Eddington ratio distribution functions (ERDFs) of type 1 and type 2 AGNs obtained by a recent study. The break in the ERDF of nearby AGNs is at log lambda*(Edd) = -1.34 +/- 0.07. This corresponds to the lambda(Edd) where AGNs transition from having most of their sky covered by obscuring material to being mostly devoid of absorbing material. A similar trend is observed for the luminosity function, which implies that most of the SMBH growth in the local universe happens when the AGN is covered by a large reservoir of gas and dust. These results could be explained with a radiation-regulated growth model, in which AGNs move in the N-H-lambda(Edd) plane during their life cycle. The growth episode starts with the AGN mostly unobscured and accreting at low lambda(Edd). As the SMBH is further fueled, lambda(Edd), N-H and the covering factor increase, leading the AGN to be preferentially observed as obscured. Once lambda(Edd) reaches the Eddington limit for dusty gas, the covering factor and N-H rapidly decrease, leading the AGN to be typically observed as unobscured. As the remaining fuel is depleted, the SMBH goes back into a quiescent phase.
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    The Accretion History of AGN : A Newly Defined Population of Cold Quasars
    (2020) Kirkpatrick, A.; Urry, C. M.; Brewster, J.; Cooke, K. C.; Estrada, M.; Glikman, E.; Hamblin, K.; Ananna, T. T.; Carlile, C.; Treister, Ezequiel; Coleman, B.; Johnson, J.; Kartaltepe, J. S.; LaMassa, S. M.; Marchesi, S.; Powell, M.; Sanders, D.; Turner, T. J.