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A simple way to improve AGN feedback prescription in SPH simulations

Published version
Peer-reviewed

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Type

Article

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Authors

Zubovas, K 
Bourne, MA 
Nayakshin, S 

Abstract

Active galactic nuclei (AGN) feedback is an important ingredient in galaxy evolution, however its treatment in numerical simulations is necessarily approximate, requiring subgrid prescriptions due to the dynamical range involved in the calculations. We present a suite of smoothed particle hydrodynamics simulations designed to showcase the importance of the choice of a particular subgrid prescription for AGN feedback. We concentrate on two approaches to treating wide-angle AGN outflows: thermal feedback, where thermal and kinetic energy is injected into the gas surrounding the supermassive black hole (SMBH) particle, and virtual particle feedback, where energy is carried by tracer particles radially away from the AGN.We show that the latter model produces a far more complex structure around the SMBH, which we argue is a more physically correct outcome. We suggest a simple improvement to the thermal feedback model - injecting the energy into a cone, rather than spherically symmetrically - and show that this markedly improves the agreement between the two prescriptions, without requiring any noticeable increase in the computational cost of the simulation.

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Keywords

accretion, accretion discs, methods: numerical, ISM: evolution, quasars: general

Journal Title

Monthly Notices of the Royal Astronomical Society

Conference Name

Journal ISSN

0035-8711
1365-2966

Volume Title

457

Publisher

Oxford University Press
Sponsorship
European Research Council (638707)
KZ is funded by the Research Council of Lithuania grant no. MIP-062/2013. MAB and SN acknowledge an STFC grant. MAB is funded by an STFC research studentship. We thank Justin Read for the use of SPHS. This research used the DiRAC complexity system, operated by the University of Leicester IT Services, which forms part of the STFC DiRAC HPC Facility (www.dirac.ac.uk). This equipment is funded by BIS National E-Infrastructure capital grant ST/K000373/1 and STFC DiRAC Operations grant ST/K0003259/1. DiRAC is part of the UK National E-Infrastructure.