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The EAGLE simulations of galaxy formation: the importance of the hydrodynamics scheme

Schaller, Matthieu; Dalla Vecchia, Claudio; Schaye, Joop; Bower, Richard G.; Theuns, Tom; Crain, Robert A.; Furlong, Michelle; McCarthy, Ian G.

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Claudio Dalla Vecchia

Joop Schaye

Richard G. Bower

Robert A. Crain

Michelle Furlong

Ian G. McCarthy


We present results from a subset of simulations from the ‘Evolution and Assembly of GaLaxies and their Environments’ (EAGLE) suite in which the formulation of the hydrodynamics scheme is varied. We compare simulations that use the same subgrid models without recalibration of the parameters but employing the standard GADGET flavour of smoothed particle hydrodynamics (SPH) instead of the more recent state-of-the-art ANARCHY formulation of SPH that was used in the fiducial EAGLE runs. We find that the properties of most galaxies, including their masses and sizes, are not significantly affected by the details of the hydrodynamics solver. However, the star formation rates of the most massive objects are affected by the lack of phase mixing due to spurious surface tension in the simulation using standard SPH. This affects the efficiency with which AGN activity can quench star formation in these galaxies and it also leads to differences in the intragroup medium that affect the X-ray emission from these objects. The differences that can be attributed to the hydrodynamics solver are, however, likely to be less important at lower resolution. We also find that the use of a time-step limiter is important for achieving the feedback efficiency required to match observations of the low-mass end of the galaxy stellar mass function.


Schaller, M., Dalla Vecchia, C., Schaye, J., Bower, R. G., Theuns, T., Crain, R. A., …McCarthy, I. G. (2015). The EAGLE simulations of galaxy formation: the importance of the hydrodynamics scheme. Monthly Notices of the Royal Astronomical Society, 454(3), 2277-2291.

Journal Article Type Article
Acceptance Date Sep 16, 2015
Publication Date Dec 11, 2015
Deposit Date Dec 7, 2015
Publicly Available Date Dec 11, 2015
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 454
Issue 3
Pages 2277-2291
Keywords Methods: numerical, Galaxies: clusters: intracluster medium, Galaxies: formation, Cosmology: theory.
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Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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