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A new way to measure supermassive black hole spin in accretion disc-dominated active galaxies.

Done , C. and Jin, C. and Middleton, M. and Ward, M.J. (2013) 'A new way to measure supermassive black hole spin in accretion disc-dominated active galaxies.', Monthly notices of the Royal Astronomical Society. .

Abstract

We show that disc continuum fitting can be used to constrain black hole spin in a subclass of narrow-line Seyfert 1 (NLS1) active galactic nuclei as their low mass and high mass accretion rate means that the disc peaks at energies just below the soft X-ray bandpass. We apply the technique to the NLS1 PG1244+026, where the optical/UV/X-ray spectrum is consistent with being dominated by a standard disc component. This gives a best estimate for black hole spin which is low, with a firm upper limit of a* <0.86. This contrasts with the recent X-ray determinations of (close to) maximal black hole spin in other NLS1 based on relativistic smearing of the iron profile. While our data on PG1244+026 do not have sufficient statistics at high energy to give a good measure of black hole spin from the iron line profile, cosmological simulations predict that black holes with similar masses have similar growth histories and so should have similar spins. This suggests that there is a problem either in our understanding of disc spectra, or/and X-ray reflection or/and the evolution of black hole spin.

Item Type:Article
Keywords:Accretion, Accretion discs, Black hole physics, Galaxies: Seyfert, Ultraviolet: galaxies, X-rays: galaxies.
Full text:PDF - Published Version (605Kb)
Status:Peer-reviewed
Publisher Web site:http://dx.doi.org/10.1093/mnras/stt1138
Publisher statement:This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Record Created:30 Jul 2013 11:05
Last Modified:30 Jul 2013 11:12

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