Journal Article

The accretion disc particle method for simulations of black hole feeding and feedback

Chris Power, Sergei Nayakshin and Andrew King

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 412, issue 1, pages 269-276
Published in print March 2011 | ISSN: 0035-8711
Published online March 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.17901.x
The accretion disc particle method for simulations of black hole feeding and feedback

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Black holes grow by accreting matter from their surroundings. However, angular momentum provides an efficient natural barrier to accretion and so only the lowest angular momentum material will be available to feed the black holes. The standard subgrid model for black hole accretion in galaxy formation simulations – based on the Bondi–Hoyle method – does not account for the angular momentum of accreting material, and so it is not clear how representative the black hole accretion rate estimated in this way is likely to be. In this paper we introduce a new subgrid model for black hole accretion that naturally accounts for the angular momentum of accreting material. Both the black hole and its accretion disc are modelled as a composite accretion disc particle. Gas particles are captured by the accretion disc particle if and only if their orbits bring them within its accretion radius Racc, at which point their mass is added to the accretion disc and feeds the black hole on a viscous time-scale tvisc. The resulting black hole accretion rate powers the accretion luminosity , which drives black hole feedback. Using a series of controlled numerical experiments, we demonstrate that our new accretion disc particle method is more physically self-consistent than the Bondi–Hoyle method. We also discuss the physical implications of the accretion disc particle method for systems with a high degree of rotational support, and we argue that the MBH–σ relation in these systems should be offset from the relation for classical bulges and ellipticals, as appears to be observed.

Keywords: accretion, accretion discs; methods: numerical; galaxies: active; galaxies: formation

Journal Article.  5319 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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