A comparative study of AGN feedback algorithms

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dc.creator Wurster, James Howard
dc.creator Thacker, Robert John, 1970-
dc.date.accessioned 2018-03-07T13:25:09Z
dc.date.available 2018-03-07T13:25:09Z
dc.date.issued 2013-05
dc.identifier.issn 0035-8711
dc.identifier.uri http://library2.smu.ca/handle/01/27343
dc.description Publisher's Version/PDF
dc.description.abstract <p>Modelling active galactic nuclei (AGN) feedback in numerical simulations is both technically and theoretically challenging, with numerous approaches having been published in the literature. We present a study of five distinct approaches to modelling AGN feedback within gravitohydrodynamic simulations of major mergers of Milky Way-sized galaxies. To constrain differences to only be between AGN feedback models, all simulations start from the same initial conditions and use the same star formation algorithm. Most AGN feedback algorithms have five key aspects: the black hole accretion rate, energy feedback rate and method, particle accretion algorithm, black hole advection algorithm and black hole merger algorithm. All models follow different accretion histories, and in some cases, accretion rates differ by up to three orders of magnitude at any given time. We consider models with either thermal or kinetic feedback, with the associated energy deposited locally around the black hole. Each feedback algorithm modifies the region around the black hole to different extents, yielding gas densities and temperatures within r &sim; 200 pc that differ by up to six orders of magnitude at any given time. The particle accretion algorithms usually maintain good agreement between the total mass accreted by Ṁdt and the total mass of gas particles removed from the simulation, although not all algorithms guarantee this to be true. The black hole advection algorithms dampen inappropriate dragging of the black holes by two-body interactions. Advecting the black hole a limited distance based upon local mass distributions has many desirably properties, such as avoiding large artificial jumps and allowing the possibility of the black hole remaining in a gas void. Lastly, two black holes instantly merge when given criteria are met, and we find a range of merger times for different criteria. This is important since the AGN feedback rate changes across the merger in a way that is dependent on the specific accretion algorithm used. Using the M<sub>BH</sub>&ndash;&sigma; relation as a diagnostic of the remnants yields three models that lie within the one-sigma scatter of the observed relation and two that fall below the expected relation. The wide variation in accretion behaviours of the models reinforces the fact that there remains much to be learnt about the evolution of galactic nuclei.</p>
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dc.description.provenance Made available in DSpace on 2018-03-07T13:25:09Z (GMT). No. of bitstreams: 1 Thacker_Robert_J_article_2013_b.pdf: 6330420 bytes, checksum: 899adb3673d6845a4ff61b5025231b33 (MD5) Previous issue date: 2013 en
dc.language.iso en en_CA
dc.publisher Oxford University Press en_CA
dc.relation.uri https://dx.doi.org/10.1093/mnras/stt346
dc.rights 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.
dc.subject.lcsh Active galactic nuclei
dc.subject.lcsh Black holes (Astronomy)
dc.subject.lcsh Astrophysics -- Mathematical models
dc.title A comparative study of AGN feedback algorithms en_CA
dc.type Text en_CA
dcterms.bibliographicCitation Monthly Notices of the Royal Astronomical Society 431(3), 2513-2534. (2013) en_CA
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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.
 
Published Version: https://dx.doi.org/10.1093/mnras/stt346
 
 

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