BASS XXXVII: The Role of Radiative Feedback in the Growth and Obscuration Properties of Nearby Supermassive Black Holes

C. Ricci, T. T. Ananna, M. J. Temple, C. M. Urry, M. J. Koss, B. Trakhtenbrot, Y. Ueda, D. Stern, F. E. Bauer, E. Treister, G. C. Privon, K. Oh, S. Paltani, M. Stalevski, L. C. Ho, A. C. Fabian, R. Mushotzky, C. S. Chang, F. Ricci, D. KakkadL. Sartori, R. Baer, T. Caglar, M. Powell, F. Harrison

Research output: Contribution to journalArticlepeer-review


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 λ 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 λ Edd * = − 1.34 ± 0.07 . This corresponds to the λ 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 HEdd plane during their life cycle. The growth episode starts with the AGN mostly unobscured and accreting at low λ Edd. As the SMBH is further fueled, λ Edd, N H and the covering factor increase, leading the AGN to be preferentially observed as obscured. Once λ 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.

Original languageEnglish
Article number67
JournalAstrophysical Journal
Issue number1
StatePublished - 1 Oct 2022


Dive into the research topics of 'BASS XXXVII: The Role of Radiative Feedback in the Growth and Obscuration Properties of Nearby Supermassive Black Holes'. Together they form a unique fingerprint.

Cite this