Journal Article

The need for hypercritical accretion in massive black hole binaries with large Kerr parameters

Enrique Moreno Méndez

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 413, issue 1, pages 183-189
Published in print May 2011 | ISSN: 0035-8711
Published online April 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.18121.x
The need for hypercritical accretion in massive black hole binaries with large Kerr parameters

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Recent measurements of the Kerr parameters of the black holes in M33 X-7 and LMC X-1 yield a= 0.84 ± 0.05 and a= 0.90+0.04−0.09, respectively. We study massive binary evolution scenarios that can reproduce such high values for the Kerr parameters. We first discuss a model with Case C mass transfer leading to a common envelope and tidal synchronization of the primary before it collapses into a black hole. We also study a Case M evolution model (which involves tidally locked, rotationally mixed, chemically homogeneous stars in a close binary). Our analysis suggests that, regardless of the specific scenario, the observed Kerr parameters for the black holes in M33 X-7 and LMC X-1 had to be obtained through hypercritical mass accretion.

Keywords: accretion, accretion discs; black hole physics; gravitation; binaries: close; X-rays: binaries

Journal Article.  7072 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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