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Title: How big can a black hole grow?
Authors: King, Andrew Robert
First Published: 17-Dec-2015
Publisher: Oxford University Press (OUP)
Citation: Monthly Notices Of The Royal Astronomical Society Letters, 2016, 456 (1), pp. L109-L112 (4)
Abstract: I show that there is a physical limit to the mass of a black hole, above which it cannot grow through luminous accretion of gas, and so cannot appear as a quasar or active galactic nucleus (AGN). The limit is Mmax ≃ 5 × 1010 M⊙ for typical parameters, but can reach Mmax ≃ 2.7 × 1011 M⊙ in extreme cases (e.g. maximal prograde spin). The largest black hole masses so far found are close to but below the limit. The Eddington luminosity ≃6.5 × 1048 erg s−1 corresponding to Mmax is remarkably close to the largest AGN bolometric luminosity so far observed. The mass and luminosity limits both rely on a reasonable but currently untestable hypothesis about AGN disc formation, so future observations of extreme supermassive black hole masses can therefore probe fundamental disc physics. Black holes can in principle grow their masses above Mmax by non-luminous means such as mergers with other holes, but cannot become luminous accretors again. They might nevertheless be detectable in other ways, for example through gravitational lensing. I show further that black holes with masses ∼Mmax can probably grow above the values specified by the black-hole–host-galaxy scaling relations, in agreement with observation.
DOI Link: 10.1093/mnrasl/slv186
ISSN: 1745-3925
eISSN: 1745-3933
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2015 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. The file associated with this record is distributed under the Creative Commons “Attribution Non-Commercial No Derivatives” licence, further details of which can be found via the following link:
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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