Journal Article

Eddington ratio and accretion efficiency in active galactic nuclei evolution

S. I. Raimundo and A. C. Fabian

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 396, issue 3, pages 1217-1221
Published in print July 2009 | ISSN: 0035-8711
Published online June 2009 | e-ISSN: 1365-2966 | DOI:
Eddington ratio and accretion efficiency in active galactic nuclei evolution

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The cosmological evolution of active galactic nuclei (AGN) is important for understanding the mechanism of accretion on to supermassive black holes and the related evolution of the host galaxy. In this work, we include objects with very low Eddington ratio (10−3–10−2) in an evolution scenario, and compare the results with the observed local distribution of black holes. We test several possibilities for the AGN population, considering obscuration and dependence with luminosity, and investigate the role of the Eddington ratio λ and radiative accretion efficiency ε on the shape of the evolved mass function. We find that three distinct populations of AGN can evolve with a wider parameter range than is usually considered, and still be consistent with the local mass function. In general, the black holes in our solutions are spinning rapidly. Taking fixed values for ε and λ neither provides a full knowledge of the evolution mechanism nor is consistent with the existence of low–Eddington–ratio objects.

Keywords: black hole physics; galaxies: active; galaxies: nuclei; quasars: general

Journal Article.  4055 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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